PRACTICALPRACTICAL RADIATION PHYSICS RADIATION PHYSICS FOR FOR

EMERGENCY MEDICAL PERSONNELEMERGENCY MEDICAL PERSONNEL

PRACTICALPRACTICAL RADIATION PHYSICS RADIATION PHYSICS FOR FOR

EMERGENCY MEDICAL PERSONNELEMERGENCY MEDICAL PERSONNEL

Module IIIModule III

Module III - 2

What is radiation?What is radiation?

Module III - 3

Ionizing radiationIonizing radiation

Module III - 4

Electromagnetic Electromagnetic rradiationadiation

GAMMA

VISIBLE X-RAYS COSMIC

INFRARED ULTRAVIOLET

MICROVAVES

TV, RADIODecreasing wave length

Increasing frequencyIncreasing photon energy

IONIZING RADIATON

Module III - 5

Forms of Forms of ionizing radiationionizing radiation

Particulate radiation

Electromagnetic radiation

consisting of atomic or subatomic particles (electrons, protons, etc.) which carry energy in the form of kinetic energy of mass in motion

in which energy is carried by oscillating electrical and magnetic fields travelling through space at speed of light

Directly ionizing

Indirectly ionizing

Module III - 6

Origin of radiationOrigin of radiation

What is the relationship between atom structure and radiation production?

Module III - 7

Atom anatomyAtom anatomy

Electron Proton Neutron

Nucleons

Module III - 8

IsotopesIsotopes

Module III - 9

Why are some nuclides Why are some nuclides

radioactiveradioactive??Neutron to proton ratio

Module III - 10

Half-lifeHalf-life

Module III - 11

The number of decaying nuclei per unit of time

The Systéme International (SI) unit of radioactivity is the Becquerel (Bq)

One Bq = 1 disintegration per second

Non-SI unit of radioactivity is the Curie (Ci)One Ci = 3,7 x 1010 transformations per secondOne milicurie (mCi) = 3,7 x 107 s-1

One microcurie (μCi) = 3.7 x 104 s-1

1 Bq = 2.7 x 10-11 Ci

AActivityctivity

Module III - 12

Atomic symbolsAtomic symbols

AXNZ

SYMBOL OF ELEMENT

MASS NUMBER (the number of protons and neutrons)

ATOMIC NUMBER (the number of protons)

53I78

131

Example:

131I or I-131

The number of neutrons

Module III - 13

E= mc2

Measured Mass

Calculated Mass

Mass-Mass-eenergy nergy rrelationshipelationship

Module III - 14

FissionFission

Module III - 15

Nuclear Nuclear rreaction and eaction and eenergy nergy pproductionroduction

Module III - 16

Mechanisms of radioactive Mechanisms of radioactive decay decay

Module III - 17

AZX A-4

Z-2Y + 42He

e.g. 23892U 234

90Th + 42He

Alpha (αAlpha (α++++) ) ddecayecay

Module III - 18

n p + e- + υ AZXA

Z+1 Y +e- + e.g. 13153 I 131

54 Xe+e-+

Beta (Beta (--) ) ddecayecay

Module III - 19

p n + e+ + υ A

ZXAZ-1 Y+e++ e.g. 18

9 F 188O+e++

PPositron ositron ((++) ) ddecayecay

Module III - 20

Electron Electron ccaptureapture

p+ + e- n +

AZX A

Z-1 Y +

12553 I 125

52 Te+

Module III - 21

Gamma (Gamma () ) eemissionmission

Module III - 22

SIMPLIFIED NUCLEAR MODEL

Gamma ray

Nuclear energy levels:Nuclear energy levels:gamma gamma rradiationadiation

Module III - 23

How does radiation How does radiation interact with matter?interact with matter?

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ExcitationExcitation

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IonizIonizatationion

Electron removal by ionization

Module III - 26

Alpha Alpha pparticle article iinteractionnteraction

Module III - 27

Interaction of alpha radiation Interaction of alpha radiation with living matterwith living matter:: e external xternal

depositiondeposition

Alpha radiation is not external hazard.

The maximum range in tissue is <0.1 mm

All alpha radiation is absorbed in stratum corneum

Module III - 28

Interaction of alpha radiation with Interaction of alpha radiation with living matterliving matter:: i internal depositionnternal deposition

Prime danger is inhalation and ingestion of alpha emitter

Module III - 29

Beta interaction with Beta interaction with mattermatter

Module III - 30

Interaction of beta Interaction of beta radiation with living matterradiation with living matter

I I I I I ı0.001 0.01 0.1 1 10 100

Cellnucleus

Celldiameter

100 cell diameter

Auger

5.3 MeV alpha

0.15 MeV beta

1.7 MeV beta

mm

beta

alpha

Module III - 31

Positron Positron iinteraction:nteraction:annihilation annihilation rreactioneaction

Module III - 32

Neutron interactionNeutron interaction

Module III - 33

Neutron Neutron aactivationctivation

Module III - 34

Interaction of gamma Interaction of gamma radiation with matterradiation with matter

In terms of ionization, gamma radiation interacts with matter in three main ways

1. Photoelectric effect

2. Compton scattering

3. Pair production

Module III - 35

Gamma interaction by Gamma interaction by photoelectric effectphotoelectric effect

Module III - 36

Gamma interaction by Gamma interaction by Compton scatteringCompton scattering

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Pair productionPair production

Module III - 38

Extranuclear Extranuclear eenergy nergy rreleaseelease

Bremsstrahlung radiation Characteristic X rays Auger electrons

Module III - 39

Bremsstrahlung Bremsstrahlung rradiationadiation

Module III - 40

Importance of Importance of bbremsstrahlung remsstrahlung X X rays in rays in rradiation adiation ssafety afety

ppracticeractice

Module III - 41

Characteristic X raysCharacteristic X rays

Module III - 42

DifferenceDifference bbetween X rays and etween X rays and ggamma amma rraysays

Module III - 43

Internal Internal cconversion:onversion:Auger Auger eelectronslectrons

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Specific Specific iionization andonization andllinear inear eenergy nergy ttransfer ransfer

(LET)(LET)

Module III - 45

Penetrating Penetrating ppower of ower of rradiationadiation

Module III - 46

Review Review ppointsoints

Characteristics of representative types of ionizing radiationparticulate, charged, and directly ionizing radiation of alpha and beta

particles particulate, uncharged, and indirectly ionizing radiation of neutrons electromagnetic, uncharged, and indirectly ionizing radiation of

gamma rays and X rays. Radiation interacts with matter via two main processes: ionization and

excitationEnergy, which comes in many forms, can be converted from one form to

another Nuclear potential energy is converted into kinetic energy through nuclear

fission Conversion of mass to energy was predicted by Albert Einstein in his

mass-energy equation, E = mc2 Penetrating power of ionizing radiation is relative to radiation type and

energy