5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of...

62
CHE-711-Teil2-FS17-1 5. Interaction of Ionizing Radiation with Matter Type of radiation charged particles photonen neutronen Uncharged „particles“ Charged particles electrons (b - ) neg. He 2+ (a), H + (p) D + (d) Recoil nuclides Fission fragments Wir können die Wechselwirkung dieser Strahlen als Elementarprozesse betrachten (Einzelprozesse) oder als makroskopische Effekte (Abschwächung, Absorption, Streuung etc.) 26.04.17

Transcript of 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of...

Page 1: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-1

5 Interaction of Ionizing Radiation with Matter

Type of radiationcharged particles

photonenneutronen Uncharged bdquoparticlesldquo

Charged particleselectrons (b-) neg

He2+ (a) H+(p) D+ (d)Recoil nuclidesFission fragments

Wir koumlnnen die Wechselwirkung dieser Strahlen als Elementarprozesse betrachten (Einzelprozesse)

oder als makroskopische Effekte (Abschwaumlchung Absorption Streuung etc)

260417

CHE-711-Teil2-FS17-2

Interaction of Ionizing Radiation with MatterPraktische Auswirkungen der Strahlung

Strahlung Bremsung Energieabnahme

Materie Physikalische chemische biologische Wirkung

Parameter welche bei der Wechselwirkung eine Rolle spielen

TeilchenMasse LadungGeschwindigkeit kinetische EnergieSpin

Materie

Atommasse M IKernladungszahl ZAnzahl e- pro VolumenDichteIonisationspotentiale

260417

CHE-711-Teil2-FS17-3

Synopsis of interactions with the electronshell

Ungeladene Teilchen PhotonenPhotoeffektComptoneffekt(Paar Erzeugung)

geladene Teilchen Kernreaktionen

PhotonenBremsstrahlungPaarbildungKernreaktionen

Neutronen Kernreaktionen

Mit den Atomkernen

Interaction of Ionizing Radiation with Matter

260417

CHE-711-Teil2-FS17-4

Wir unterscheiden zwischen direkt ionisierend a b- b+ hellip

Energie reicht aus durch Stoss Ionen zu erzeugen

und indirekt ionisierend n + g setzen erst im Material Ionen frei

In the context of radiation absorption two definitions are important

linear stopping power

and linear energy transfer

If no Bremsstrahlung (see later) SI and LI are equal otherwise there will be a substantial difference

also important

Ionizing Radiation

260417

CHE-711-Teil2-FS17-5

Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen

Geladene Teilchen - Bremsung durch unelastische Streuung

- Ionisation und Anregung

Interaction of Ionizing Radiation with Matter

260417

CHE-711-Teil2-FS17-6

by collision with electrons the incident particle ionizes matter

the mean energy to remove an electron is called the W-factor

W-factor for air is 3385eVIP

When the charged particle travels through matter it makes

an energy dependent number of ionization length

this is the specific ionization SI

we can determine the mean energy loss per path length

LET = SI∙WLinear Energy Transfer

Ionizing Radiation

260417

CHE-711-Teil2-FS17-7

The lower the energy the higher the SI

since probability of interaction with shell electron increases

Bragg Peak

Ionizing Radiation

260417

CHE-711-Teil2-FS17-8

Letlsquos make an example

241 Am was in smoke detectors Ea=548 MeV

specific ionization (SI) = 34104 IPcm

LET = 34middot104middot338 = 12 MeVcm

Range = = = 48 cm

This is the maximum range since the SI increases dramatically at the end of the path

Ionizing Radiation

260417

CHE-711-Teil2-FS17-9

Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)

RSP = RairRabs (R = Range)

RSP values for some materials and particles

Ionizing Radiation

260417

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 2: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-2

Interaction of Ionizing Radiation with MatterPraktische Auswirkungen der Strahlung

Strahlung Bremsung Energieabnahme

Materie Physikalische chemische biologische Wirkung

Parameter welche bei der Wechselwirkung eine Rolle spielen

TeilchenMasse LadungGeschwindigkeit kinetische EnergieSpin

Materie

Atommasse M IKernladungszahl ZAnzahl e- pro VolumenDichteIonisationspotentiale

260417

CHE-711-Teil2-FS17-3

Synopsis of interactions with the electronshell

Ungeladene Teilchen PhotonenPhotoeffektComptoneffekt(Paar Erzeugung)

geladene Teilchen Kernreaktionen

PhotonenBremsstrahlungPaarbildungKernreaktionen

Neutronen Kernreaktionen

Mit den Atomkernen

Interaction of Ionizing Radiation with Matter

260417

CHE-711-Teil2-FS17-4

Wir unterscheiden zwischen direkt ionisierend a b- b+ hellip

Energie reicht aus durch Stoss Ionen zu erzeugen

und indirekt ionisierend n + g setzen erst im Material Ionen frei

In the context of radiation absorption two definitions are important

linear stopping power

and linear energy transfer

If no Bremsstrahlung (see later) SI and LI are equal otherwise there will be a substantial difference

also important

Ionizing Radiation

260417

CHE-711-Teil2-FS17-5

Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen

Geladene Teilchen - Bremsung durch unelastische Streuung

- Ionisation und Anregung

Interaction of Ionizing Radiation with Matter

260417

CHE-711-Teil2-FS17-6

by collision with electrons the incident particle ionizes matter

the mean energy to remove an electron is called the W-factor

W-factor for air is 3385eVIP

When the charged particle travels through matter it makes

an energy dependent number of ionization length

this is the specific ionization SI

we can determine the mean energy loss per path length

LET = SI∙WLinear Energy Transfer

Ionizing Radiation

260417

CHE-711-Teil2-FS17-7

The lower the energy the higher the SI

since probability of interaction with shell electron increases

Bragg Peak

Ionizing Radiation

260417

CHE-711-Teil2-FS17-8

Letlsquos make an example

241 Am was in smoke detectors Ea=548 MeV

specific ionization (SI) = 34104 IPcm

LET = 34middot104middot338 = 12 MeVcm

Range = = = 48 cm

This is the maximum range since the SI increases dramatically at the end of the path

Ionizing Radiation

260417

CHE-711-Teil2-FS17-9

Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)

RSP = RairRabs (R = Range)

RSP values for some materials and particles

Ionizing Radiation

260417

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 3: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-3

Synopsis of interactions with the electronshell

Ungeladene Teilchen PhotonenPhotoeffektComptoneffekt(Paar Erzeugung)

geladene Teilchen Kernreaktionen

PhotonenBremsstrahlungPaarbildungKernreaktionen

Neutronen Kernreaktionen

Mit den Atomkernen

Interaction of Ionizing Radiation with Matter

260417

CHE-711-Teil2-FS17-4

Wir unterscheiden zwischen direkt ionisierend a b- b+ hellip

Energie reicht aus durch Stoss Ionen zu erzeugen

und indirekt ionisierend n + g setzen erst im Material Ionen frei

In the context of radiation absorption two definitions are important

linear stopping power

and linear energy transfer

If no Bremsstrahlung (see later) SI and LI are equal otherwise there will be a substantial difference

also important

Ionizing Radiation

260417

CHE-711-Teil2-FS17-5

Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen

Geladene Teilchen - Bremsung durch unelastische Streuung

- Ionisation und Anregung

Interaction of Ionizing Radiation with Matter

260417

CHE-711-Teil2-FS17-6

by collision with electrons the incident particle ionizes matter

the mean energy to remove an electron is called the W-factor

W-factor for air is 3385eVIP

When the charged particle travels through matter it makes

an energy dependent number of ionization length

this is the specific ionization SI

we can determine the mean energy loss per path length

LET = SI∙WLinear Energy Transfer

Ionizing Radiation

260417

CHE-711-Teil2-FS17-7

The lower the energy the higher the SI

since probability of interaction with shell electron increases

Bragg Peak

Ionizing Radiation

260417

CHE-711-Teil2-FS17-8

Letlsquos make an example

241 Am was in smoke detectors Ea=548 MeV

specific ionization (SI) = 34104 IPcm

LET = 34middot104middot338 = 12 MeVcm

Range = = = 48 cm

This is the maximum range since the SI increases dramatically at the end of the path

Ionizing Radiation

260417

CHE-711-Teil2-FS17-9

Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)

RSP = RairRabs (R = Range)

RSP values for some materials and particles

Ionizing Radiation

260417

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 4: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-4

Wir unterscheiden zwischen direkt ionisierend a b- b+ hellip

Energie reicht aus durch Stoss Ionen zu erzeugen

und indirekt ionisierend n + g setzen erst im Material Ionen frei

In the context of radiation absorption two definitions are important

linear stopping power

and linear energy transfer

If no Bremsstrahlung (see later) SI and LI are equal otherwise there will be a substantial difference

also important

Ionizing Radiation

260417

CHE-711-Teil2-FS17-5

Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen

Geladene Teilchen - Bremsung durch unelastische Streuung

- Ionisation und Anregung

Interaction of Ionizing Radiation with Matter

260417

CHE-711-Teil2-FS17-6

by collision with electrons the incident particle ionizes matter

the mean energy to remove an electron is called the W-factor

W-factor for air is 3385eVIP

When the charged particle travels through matter it makes

an energy dependent number of ionization length

this is the specific ionization SI

we can determine the mean energy loss per path length

LET = SI∙WLinear Energy Transfer

Ionizing Radiation

260417

CHE-711-Teil2-FS17-7

The lower the energy the higher the SI

since probability of interaction with shell electron increases

Bragg Peak

Ionizing Radiation

260417

CHE-711-Teil2-FS17-8

Letlsquos make an example

241 Am was in smoke detectors Ea=548 MeV

specific ionization (SI) = 34104 IPcm

LET = 34middot104middot338 = 12 MeVcm

Range = = = 48 cm

This is the maximum range since the SI increases dramatically at the end of the path

Ionizing Radiation

260417

CHE-711-Teil2-FS17-9

Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)

RSP = RairRabs (R = Range)

RSP values for some materials and particles

Ionizing Radiation

260417

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 5: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-5

Uumlbersicht der Wechselwirkung (von Materie) mit Elektronen

Geladene Teilchen - Bremsung durch unelastische Streuung

- Ionisation und Anregung

Interaction of Ionizing Radiation with Matter

260417

CHE-711-Teil2-FS17-6

by collision with electrons the incident particle ionizes matter

the mean energy to remove an electron is called the W-factor

W-factor for air is 3385eVIP

When the charged particle travels through matter it makes

an energy dependent number of ionization length

this is the specific ionization SI

we can determine the mean energy loss per path length

LET = SI∙WLinear Energy Transfer

Ionizing Radiation

260417

CHE-711-Teil2-FS17-7

The lower the energy the higher the SI

since probability of interaction with shell electron increases

Bragg Peak

Ionizing Radiation

260417

CHE-711-Teil2-FS17-8

Letlsquos make an example

241 Am was in smoke detectors Ea=548 MeV

specific ionization (SI) = 34104 IPcm

LET = 34middot104middot338 = 12 MeVcm

Range = = = 48 cm

This is the maximum range since the SI increases dramatically at the end of the path

Ionizing Radiation

260417

CHE-711-Teil2-FS17-9

Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)

RSP = RairRabs (R = Range)

RSP values for some materials and particles

Ionizing Radiation

260417

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 6: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-6

by collision with electrons the incident particle ionizes matter

the mean energy to remove an electron is called the W-factor

W-factor for air is 3385eVIP

When the charged particle travels through matter it makes

an energy dependent number of ionization length

this is the specific ionization SI

we can determine the mean energy loss per path length

LET = SI∙WLinear Energy Transfer

Ionizing Radiation

260417

CHE-711-Teil2-FS17-7

The lower the energy the higher the SI

since probability of interaction with shell electron increases

Bragg Peak

Ionizing Radiation

260417

CHE-711-Teil2-FS17-8

Letlsquos make an example

241 Am was in smoke detectors Ea=548 MeV

specific ionization (SI) = 34104 IPcm

LET = 34middot104middot338 = 12 MeVcm

Range = = = 48 cm

This is the maximum range since the SI increases dramatically at the end of the path

Ionizing Radiation

260417

CHE-711-Teil2-FS17-9

Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)

RSP = RairRabs (R = Range)

RSP values for some materials and particles

Ionizing Radiation

260417

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 7: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-7

The lower the energy the higher the SI

since probability of interaction with shell electron increases

Bragg Peak

Ionizing Radiation

260417

CHE-711-Teil2-FS17-8

Letlsquos make an example

241 Am was in smoke detectors Ea=548 MeV

specific ionization (SI) = 34104 IPcm

LET = 34middot104middot338 = 12 MeVcm

Range = = = 48 cm

This is the maximum range since the SI increases dramatically at the end of the path

Ionizing Radiation

260417

CHE-711-Teil2-FS17-9

Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)

RSP = RairRabs (R = Range)

RSP values for some materials and particles

Ionizing Radiation

260417

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 8: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-8

Letlsquos make an example

241 Am was in smoke detectors Ea=548 MeV

specific ionization (SI) = 34104 IPcm

LET = 34middot104middot338 = 12 MeVcm

Range = = = 48 cm

This is the maximum range since the SI increases dramatically at the end of the path

Ionizing Radiation

260417

CHE-711-Teil2-FS17-9

Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)

RSP = RairRabs (R = Range)

RSP values for some materials and particles

Ionizing Radiation

260417

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 9: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-9

Interaction with other materials SI will change since e--density changesone measure is the relative stopping power (see before)

RSP = RairRabs (R = Range)

RSP values for some materials and particles

Ionizing Radiation

260417

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 10: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-10

Ranges in air for different particles and energies

Ionizing Radiation

260417

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 11: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-11

Since not every collision leads to ionisation the average energy loss for ionisation is larger than the minimal Ie of the atoms

Bethe and Bloch proposed a bdquosimpleldquo formula for energy loss along a track considering the nature of the absorber

-The most important interaction of electrons with matter is inelastic scattering with electrons from the shells

thereby ions are generated

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 12: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-12

mit me = Ruhemasse Elektrone0 = Dielektrizitaumltskonst VakuumaN = Anzahldichte des Materialsv = Geschw ElektronsT = mittlere Ionisierungsdichte des Materials

please note since e- are light particles relativistic effects have to be considered

E = 100 keVE = 1000 keV

v = 055 cv = 094 c

m = 12 ∙ mo

m = 3 ∙ mo

for lower energies the relativistic effects can be neglected

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 13: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-13

both formulas predict a minimum value

depending only on the mass of the particle

thus the slower the particle the more ionization per length will appear

dEdx at a certain energy

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 14: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-14

absorption of electrons (b- radiation)

Note typical b- decay shows a continuous energy distribution hence it has many low energy electrons

Y(x) = Y(0) ∙ e-micro∙x

with micro = konst

or N(x) = N0 ∙ e-micro∙x

with micro = linear absorption coefficient (see x-ray crystallography)

inspecting the Bethe-Bloch formula it is obviously an exponential formula

empiricallyit translates into

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 15: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-15

thus the absorption of electrons decreases linearlyoften instead of path x one takes mass-equivalent range d = d∙ x

then

with microd = mass absorption coefficient

note that micro is a function of the electron energy and the material

it allows to calculate the maximum range of electrons in a material

it allows to calculate the thickness of materials for shielding

absorption of electrons (b- radiation)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 16: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-16

Example equivalent range of e- in Al

one can easily calculate the path for reducing the e--flux to 50

x12 can be determined experimentally and micro be calculated for a particular material

andx12 = ln2micro

d12 = (ln2)(micro8)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 17: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-17

There exists also a semiempirical relationship between micro d and Emax

and there are semiempirical relationships for connecting range with electron energy

(015 lt Eβ lt 08 MeV)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 18: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-18

Calculate the maximum range of different β-emitters

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 19: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-19

How much energy can be lost in a single collision

of particular interest collision with a shell electron

maximum energy transfer

incoming particle mass Mi speed Vi1

electron mass me speed 0

after collision Mi v2 me ve

Energy frac12 Mimiddotv12 = frac12 Mimiddotv2

2 + frac12 memiddot ve2

momentum Mi middotv1 = Miv2 + memiddotve (non-relativistic)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 20: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-20

maximum energy transfer

speed of reflected particle

MET Qmax = nicht relativistisch

If Mi = me (electron on electron)

then Qmax = E

explains why light particles have a zigzag pass in matter

take an a-particle colliding with an e-

me = 9109∙10-31 kg ma = 6646∙10-27 kg 5468 ∙10-4 u 40026 u

QmaxE = = 000054 = 005

Thatlsquos why heavy particles travel straight

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 21: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-21

before going further what is the speed of a particle of a given energy E and rest mass m0

easy E = frac12 mo∙v2 true for energies with speed away from c

relativistic equation

aufgeloumlst for an electron with E = 100keV

1 eV = 1602∙10-19 J mo = 9109 ∙10-31 kg c = 3 ∙108 msec

E = 100 keV v = 121 ∙108 msec (rel)132 ∙108 msec (nicht rel)

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 22: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-22

of speed of light c

this can be calculated for all particles back to maximum energy transfer

Qmax =

reduces to Qmax = 2g2∙me ∙ vi since ltltlt1 usually

with

Ionizing Radiation Electrons

260417

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 23: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-23

Examples for protons H

Proton KineticEnergy E(MeV)

011

10100

103

104

105

106

107

Qmax(MeV)

00002200022002190229333136106 x 104

538 x 105

921 x 106

Maximum percentageenergy transfer

100QmaxE

02202202202303314

106538921

Ionizing Radiation Protons

260417

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 24: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-24

Specific ionizations for eg elecrons in air can be calculated if their velocity is known

SI =

(keep in mind that v changes upon absorption)

example 32P (Emax (b) = 1709 MeV)

calculate v = 26∙108 ms b = 087

SI = 6000 IPm

LET = 02 MeVcm

keep in mind that not only ionization takes place but also scattering of electrons at the nucleus

Ionizing Radiation

260417

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 25: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-25

Ionizing Radiation Bremsstrahlung

The most important interaction is inelastic scattering

Which results in the emission of Bremsstrahlung

260417

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 26: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-26

The stopping power of atoms or materials does notonly depend on ionization but also on

direct electron-target nucleus interactions

This energy loss generates photons so called bdquoBremsstrahlungldquo

thus total stopping power

From Bethe-Formula the ratio between collision and radiation is

thus the higher the energy the more Bremsstrahlung

and the higher the atomic number the more Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 27: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-27

since the stopping efficiency by Bremsstrahlung increases by z2 but the stopping by ionization only by z

the formation of Bremsstrahlung increases with E

The following formula gives this ratio

example Pb shielded source of 90Y(Emax = 228MeV) produces 10 Bremsstrahlung

Bremsstrahlung

260417

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 28: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-28

Bremsstrahlung

260417

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 29: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-29

The Bremsstrahlung is used to produce Synchrotronradiation

Bremsstrahlung

260417

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 30: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-30

this means donlsquot shield b-emitters with lead

letlsquos make an example

How much energy does a 22 MeV electron loose by passing

through 5mm Lucite (Acrylglas) r = 119

1 We calculate the maximum range of 22 MeV using the formula for low Z materials

R = 0412∙E(127-0095middotlnE)

= 106 gcm2

Bremsstrahlung

260417

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 31: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-31

The same result can be received from the range vs energy graph

Bremsstrahlung

260417

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 32: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-32

2 now we relate the stopping power and the energy by the formula for low Z materials

InEafter = 663-324(329-lnEbefore)frac12 = 0105

Eafter = 111 MeV and 109 MeV is absorbed

with the formula from phellip 00039 are converted to Bremsstrahlung (423 kev)

Bremsstrahlung

260417

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 33: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-33

Interaction of g-radiation and x-rays with matter

Photo Effect Compton Effect Pair Formation

Three principle modes of interaction

- Photons do not steadily lose energy as they penetrate matter

- The distance the photons can travel before they interact withan atom is governed statistically by a probability whichdepends on the specific medium and on the photon energy

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 34: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-34CHE-611-FS10-Teil2-34

- interaction between g - quanta andelectrons of the inner shells

- emission of a photoelectron(ionization)

- dominates with low photon energies- bdquoabsorptionldquo of the g -quantIn coming g-quant

Photo electron

Photon

radiation

Electron of the shell

L- shell

K- shell

g-quant

Higherenergylevell

Lowerenergylevell

The Photo Effect

- electron gap filled by an outer-sphere electron (X-ray fluorescence secondary radiation)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 35: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-35

The Photo Effect

The photoelectron contains the complete energy of the g ndash quant minusan energy j that the electron expends in escaping the atom

Every g-rays emitting nucleus emits g-quanta with a distinct energies(fingerprint)

g ndash spectroscopy

jn -=hT

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 36: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-36

The Photo Effect

The photo effect depends strongly on the atomic number Z and theenergy hn of the photons

3)(4nhZyprobabilit =

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 37: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-37

- interaction between g -quanta and e- of the outer electron shells (Compton electrons)

- emission of a Compton electron (ionization)

- g -quant loses energy (shift to longer wavelengths Compton shift)

- the Compton shift only depends on the scattered angle not on the wave length ofthe incident-photon

- resulting quant can undergo more Compton reaction or finally photo reactions

incoming g-quant

scatteredg-quant

Compton electron

The Compton effect

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 38: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-38

- The emitted Compton electrons have no defined energy (Compton continuum)

The Compton effect

Compton continuum

httpenwikipediaorgwikiFileGammaspektrum_Uranerzjpg

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 39: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-39

In coming g-quant

The bdquomysticalldquo Pair Formation

Never forget 2cmE times=

THORN A photon with an energy of at least 1022 MeV can be converted into an e+ e- pair in the field of an atomic nucleus

22 cemh sup3n

- Excess energy is kinetic energy of the products

- The distribution of the excess energy is continuous

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 40: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-40

The bdquomysticalldquo Pair Formation

- Pair production becomes more likely with increasing photon energy

- The probability also increases with the atomic number

2Zyprobabilit raquo

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 41: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-41

The Annihilation of Positrons

The produced positron immediately reacts with an electron

nhee =-++

Since the total momentum before the decay is zero two photons mustbe produced in order to conserve momentum

The produced photons going off in opposite directions

nhcem =22Due to the photon energy is 511 keV (1022 MeV2)

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 42: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-42

- The presents of 511 keV annihilation photons around anypositron source is always a potential radiation hazard

Advantages and Disadvantages of the Pair Formation

Disadvantage

Advantages

- Pair Formation helps to convert high energy photons (gt 1022 MeV) into photons with less energy (511 keV)

THORN easier to shield

Question How would you shield a g-emitter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 43: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-43

Ato

mic

num

ber o

f abs

orbe

rOccurrence of the three mechanisms of interaction

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 44: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-44

Interaction of Neutrons with Matter- Neutrons have no charge and donlsquot interact with the shell electron

(no direct ionization)

- Interactions between neutrons and matter are interactions with nuclei(only secondary ionization processes)

Classification of Neutrons

Thermal Neutrons Energy distribution according to the Maxwell ndash Boltzmann equationEnergy asymp 0025 eV

(most probable energy in the distribution at 20degC)

Slow Neutrons Also called ldquointermediaterdquo of ldquoresonancerdquo neutronsEnergy le 01 MeV

Fast Neutrons Energy le 20 MeV

Relativistic Neurtons Energy gt 20 MeV

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 45: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-45

Elastic and inelastic impacts

slow neutronW2

W3

Fast neutronW1

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

W1 gt W2 + W3

Energy range 1 - 10 MeV- emission of excess energy as g -quants

- main mechanisms elastic and inelastic impacts neutron capturing

Interaction of Neutrons with Matter

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 46: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-46

Energy range 10 keV - 1 MeV

Back-scattered nucleusW3

slow neutronW2

W1 = W2 + W3

Fast neutronW1

Interaction of Neutrons with Matter

Elastic Scattering

2)(4

max mMnmMEQ

+=

M = Mass of a neutronm = Mass of the recoil nucleusEn = Kinetic energy of the neutron

Maximum Fraction of Energy Lost Qmax En

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 47: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-47

Interaction of Neutrons with Matter

If a neutron reaches thermal energies it will move aboutrandomly by elastic scattering until absorbed by a nucleus

Slowing-down neutrons is called neutron moderation

Nuclear reaction (np) (n 2n) (n a) (n g)

Neutron Activation Analysis

Ionizing Radiation High Energy Photons

260417

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 48: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-48

6 Biological action of ionizing radiation

260417

Interaction of radiation with a biological system leads to an energy transfer

The biological impact depends on

type of radiation

type of irradiated biological material

How to quantify the biological impact

How to quantify the amount of transferred energy

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 49: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-49

6 Biological action of ionizing radiation

Dose and Dose Rate

air irradiated of masscharges producedI =

mQIDD

=

SI Unitair kg

pairs Ion10625kg

C(As)I 18times==

- Measurement of the ionisation in an ionisation chamber

- gasfilled container with a window of thin material

- electric current is produced by ionswhich are produced by the influenceof radiation

Ionisation chamber

Radiationsource

R10388air kg

C1airkg

C102581R 34

times=times

=-

Old unit R (Roentgen)

Strahlenmenge die noumltig ist um positive und negative Ionen von einerelektrostatischen Einheit im Volumen von einem Kubikzentimeter (1 cmsup3)Luft bei Normalbedingungen freizusetzenEine Dosis von 1 Roumlntgen pro Kubikzentimeter Luft asymp 2 MilliardenIonenpaare

260417

Ion Dose (Exposure)

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 50: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-50

Old unit rd (rad) 1rd = 10-2 Gy

ΔmΔW D

massenergy radiationabsorbedD ==

with this information we have a direct information about the transfered energy

From Ion Dose to Energy Dose

the formation of 1 ion pair requires 34 eV

SI Unit 1 Gy (Gray) 1 Gy = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 51: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-51

old unit1 rem 1 Sv = 100 rem (roentgen equivalent men)

Equivalent dose H = D middot W

W = weighting factor of the radiation

From Energy Dose to Equivalent Dose

Damage of organic material (tissue) can only be expected if the energy isabsorbed by the tissue (Interactions radiation -matter)

The bigger the absorption is the bigger is the impact

Energy dose exclusively reflects the pure energy value (not the impact)

Highly ionizing radiation has a higher impact than weakly ionizing (a gt n gt b g X)

SI Unit 1 Sv (Sievert) 1 Sv = 1 Jkg

260417

6 Biological action of ionizing radiation

CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

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CHE-711-Teil2-FS17-52

Equivalent dose H = D middot W

W = weighting factor of the radiation

Radiation types W X-rays g- and szlig-radiation 1

Neutron radiation about 10

a - radiation 20

Normal cell

Damaged cell

Biological sample after irradiation with Beta-Particles

relative destruction 1Energy dose 1 Gy

Biological sample after irradiation with Alpha-Particles

relative destruction 1Energy dose 005 Gy

Equivalent Dose

Dose rate dTdH (Sv h)

260417

6 Biological action of ionizing radiation

Representing the stochastic health effects of ionizing radiation on the human bodyEquivalent Dose enables the comparison of different types of radiation

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 53: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-53260417

6 Biological action of ionizing radiation

Radiobiological Functional Chain

Physical Processenergy transfer

molecular amp biochemical changes

cellular changessomatic cell gamete cell

acute direkt damage

non-malignant later damage

neoplasms(cancer leukemia)

genetic damage

instantaneous

minutes

hours

days

weeksmonth

years

nextgeneration

deterministic stochastic

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 54: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-54260417

6 Biological action of ionizing radiationDirect vs Indirect Radiation Effect

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 55: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-55260417

6 Biological action of ionizing radiationDNA Damages

Single- Double-strand breaks Chemical bond betweenNeighboring nucleotides

Chemical modificationof a nucleotide (mutation) losing of one nucleobase

Chemical linkage of two strands

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 56: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-56260417

6 Biological action of ionizing radiationDNA Damages

spontaneous radiation-induced

Event per second per hour per year per mGy

Single-strand break 14 ca 5 x 103 ca 44 x 107 10

Double-strand break 004

Depurination ca 15 x 103 ca 14 x 107 001

Base damage 08 ca 125 x 103 ca 11 x 107 095

Total 22 ca 8 x 103 ca7 x 107 ca 20

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 57: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-57260417

6 Biological action of ionizing radiationRadiation Damages

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 58: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-58

Bei den somatischen Strahlenwirkungen unterscheidet man zwischen stochastischen und deterministischen Strahlenwirkungen

httpwwwkernfragendekernfragenlexikonsstrahlenschaeden_beim_menschenphp260417

6 Biological action of ionizing radiationStochastic vs Deterministic Effects

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 59: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-59260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 60: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-60260417

6 Biological action of ionizing radiationDeterministic Radiation Damage

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 61: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-61260417

6 Biological action of ionizing radiation

Strahlenverbrennung der Haut

Deterministic Radiation Damage

Strahlendermatitis und Epilation

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits

Page 62: 5. Interaction of Ionizing Radiation with Matter2fe607d0-fe61-47e8-b55d-839480… · Interaction of Ionizing Radiation with Matter Type ofradiation chargedparticles photonen neutronen

CHE-711-Teil2-FS17-62

Equivalent Dose Limits StSG (28122004) StSV (01012008)Equivalent Dose Limits (annual)Body 1 mSv (public)

20 mSv (people working with activity)max 50 mSv (exceptional with permission)

Equivalent Dose Limits for tissues amp organs (annual)Lens of eye 150 mSvSkin hands and feet 500 mSv

Biological action Dose and dose rate

260417

Dose Limits