PRACTICAL RADIATION PHYSICS FOR EMERGENCY MEDICAL PERSONNEL Module III.
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Transcript of PRACTICAL RADIATION PHYSICS FOR EMERGENCY MEDICAL PERSONNEL Module III.
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 - 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 - 9
Why are some nuclides Why are some nuclides
radioactiveradioactive??Neutron to proton ratio
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 - 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 - 22
SIMPLIFIED NUCLEAR MODEL
Gamma ray
Nuclear energy levels:Nuclear energy levels:gamma gamma rradiationadiation
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 - 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 - 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 - 38
Extranuclear Extranuclear eenergy nergy rreleaseelease
Bremsstrahlung radiation Characteristic X rays Auger electrons
Module III - 40
Importance of Importance of bbremsstrahlung remsstrahlung X X rays in rays in rradiation adiation ssafety afety
ppracticeractice
Module III - 44
Specific Specific iionization andonization andllinear inear eenergy nergy ttransfer ransfer
(LET)(LET)
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