IAEAInternational Atomic Energy Agency
RADIATION PROTECTION INDIAGNOSTIC AND
INTERVENTIONAL RADIOLOGY
L 3: Biological effects of ionizing radiation
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
IAEA 3 : Biological effects of ionizing radiation 2
Introduction
• Subject matter: radiobiology
• The mechanisms of different types of biological effects following exposure to ionizing radiation
• Types of models used to derive risk coefficients for estimating the detriment
IAEA 3 : Biological effects of ionizing radiation 3
Topics
• Classification of radiation health effects
• Factors affecting radio sensitivity
• Dose-effect response curve
• Whole body response: acute radiation syndrome
• Effects of antenatal exposure and delayed effects of radiation
• Epidemiology
IAEA 3 : Biological effects of ionizing radiation 4
Overview
• To become familiar with the mechanisms of different types of biological effects following exposure to ionizing radiation. To be aware of the models used to derive risk coefficients for estimating the detriment.
IAEAInternational Atomic Energy Agency
Part 3: Biological effect of ionizing radiation
Topic 1: Classification of radiation health effects
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
IAEA 3 : Biological effects of ionizing radiation 6
Radiation health effects
DETERMINISTICSomaticClinically attributable in the exposed individual
CELL DEATH
STOCHASTICsomatic & hereditaryepidemiologically attributable in large populations
ANTENATALsomatic and hereditary expressed in the foetus, in the live born or descendants
BOTH
TYPEOF
EFFECTS
CELL TRANSFORMATION
IAEA 3 : Biological effects of ionizing radiation 7
Biological effects of ionizing radiation
• Deterministic• e.g. Lens opacities, skin
injuries,
• infertility, epilation, etc
• Stochastic• Cancer, genetic effects.
IAEA 3 : Biological effects of ionizing radiation 8
• Deterministic(Threshold/non-stochastic)• Existence of a dose
threshold value (below this dose, the effect is not observable)
• Severity of the effect increases with dose
• A large number of cells are involved
Radiation injury from an industrial source
Deterministic effects
IAEA 3 : Biological effects of ionizing radiation 9
• Cataracts of the lens of the eye 2-10 Gy
• Permanent sterility
• males 3.5-6 Gy
• females 2.5-6 Gy
• Temporary sterility
• males 0.15 Gy
• females 0.6 Gy
dose
Severity ofeffect
threshold
Threshold Doses for Deterministic Effects
IAEA 3 : Biological effects of ionizing radiation 10
Stochastic Effects
• Stochastic(Non-Threshold)• No threshold
• Probability of the effect increases with dose
• Generally occurs with a single cell
• e.g. Cancer, genetic effects
DIRECT ACTIONDIRECT ACTION INDIRECT ACTIONINDIRECT ACTION
IAEA 3 : Biological effects of ionizing radiation 16
Outcomes after cell exposure
DAMAGEREPAIRED
CELL DEATH(APOPTOSIS)
TRANSFORMED CELL
DAMAGE TO DNA
IAEA 3 : Biological effects of ionizing radiation 17
Outcomes after cell exposure
DAMAGE REPAIRED
CELL NECROSIS
OR
APOPTOSIS
TRANSFORMEDCELL
DAMAGE TO DNA
How DNA is
repaired ?
IAEA 3 : Biological effects of ionizing radiation 20
Repair of DNA damage
• RADIOBIOLOGISTS ASSUME THAT THE REPAIR SYSTEM IS NOT 100% EFFECTIVE.
IAEA 3 : Biological effects of ionizing radiation 22
Outcomes after cell exposure
DAMAGE REPAIRED
CELL NECROSIS OR APOPTOSIS
TRANSFORMED CELL
DAMAGE TO DNA
Normal human
lymphocyte:
chromosomes
uniformly
distributed
Apoptotic cell:chromosomes
and nucleusfragmented
and collapsedinto apoptotic
bodies
IAEA 3 : Biological effects of ionizing radiation 25
Effects of cell death
Acute dose (in mSv)
Probability of cell death
5000
100%
IAEA 3 : Biological effects of ionizing radiation 26
Outcomes after cell exposure
DAMAGE REPAIRED
CELL NECROSIS OR
APOPTOSIS
TRANSFORMED CELL
DAMAGE TO DNA
IAEA 3 : Biological effects of ionizing radiation 27
Chromosomal deletions
IAEA 3 : Biological effects of ionizing radiation 28
Chromosomal translocations
CANCER INITIATION TUMOR PROMOTION
MALIGNANT PROGRESSION
METASTASISMALIGNANT TRANSFOMATION
STEAM CELL
DIVISION
MUTATION
NECROSIS ORAPOPTOSIS
NORMAL TISSUE
CELL INITIATION
An initiating event
creates a mutation in
one of the basal cells
DYSPLASIA
More mutations occurred.
The initiated cell has
gained proliferative
advantages.
Rapidly dividing cells
begin to accumulate
within the epithelium.
BENIGN TUMOR
More changes within
the proliferative cell
line lead to full tumor
development.
MALIGNANT TUMOR
The tumor breaks
through the basal lamina.
The cells are irregularly
shaped and the cell line
is immortal. They have
an increased mobility
and invasiveness.
METASTASIS
Cancer cells break
through the wall of a
lymphatic vessel or blood
capillary. They can now
migrate throughout the
body and potentially seed
new tumors.
A simple generalized scheme for multistage oncogenesis
Damage to chromosomal DNAof a normal target cell
Failure to correctDNA repair
Appearance of specificneoplasia-initiating mutation
Promotional growthof pre-neoplasm
Conversion to overtlymalignant phenotype
Malignant progression and tumour spread
10-6
10-12
10-9
10-15
10-3
1 second
1 hour
1 day
1 year
100 years
1 ms
100
109
106
103
Energy deposition
Excitation/ionization
Initial particle tracks
Radical formation
PHYSICAL INTERACTIONS
PHYSICO-CHEMICAL INTERACTIONS
BIOLOGICAL RESPONSE
MEDICAL EFFECTS
Diffusion, chemical reactions
Initial DNA damage
DNA breaks / base damage
Repair processesDamage fixation
Cell killing
Promotion/completion
TeratogenesisCancer
Hereditary defects
Proliferation of "damaged" cells
Mutations/transformations/aberrations
TI M
E (
sec)
Timing of events leading to radiation effects.
IAEAInternational Atomic Energy Agency
Part 3: Biological effect of ionizing radiation
Topic 2: Factors affecting the radiosensitivity
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
IAEA 3 : Biological effects of ionizing radiation 40
Radiosensitivity [RS] (1)
• RS = Probability of a cell, tissue or organ of suffering an effect per unit of dose.
• Bergonie and Tribondeau (1906): “RS LAWS”: RS will be greater if the cell:• Is highly mitotic.
• Is undifferentiated.
• Has a high cariocinetic future.
IAEA 3 : Biological effects of ionizing radiation 41
Radiosensitivity (2)
Muscle
Bones
Nervous system
Skin
Mesoderm organs (liver, heart, lungs…)
Bone Marrow
Spleen
Thymus
Lymphatic nodes
Gonads
Eye lensLymphocytes (exception to the RS laws)
Low RSMedium RSHigh RS
IAEA 3 : Biological effects of ionizing radiation 42
Factors affecting the radiosensitivity
G1
S
G2
M
G0
LET
LET% s
urv
ivo
r c
ell
s
MM
• Physical• LET (linear energy transfer): RS• Dose rate: RS
• Chemical• Increase RS: OXYGEN, cytotoxic drugs.• Decrease RS: SULFURE (cys, cysteamine…)
• Biological• Cycle status:
RS: G2, M RS: S
• Repair of damage (sub-lethal damage may be repaired e.g. fractionated dose)
IAEAInternational Atomic Energy Agency
Part 3: Biological effect of ionizing radiation
Topic 3: Dose-effect response curve
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
IAEA 3 : Biological effects of ionizing radiation 44
Systemic effects
• Effects may be morphological and/or functional• Factors:
• Which Organ• How much Dose
• Effects • Immediate (usually reversible): < 6 months e.g.:
inflammation, bleeding.• Delayed (usually irreversible): > 6 months e.g.: atrophy,
sclerosis, fibrosis.• Categorization of dose
• < 1 Gy: LOW DOSE• 1-10 Gy: MODERATE DOSE• > 10 Gy: HIGH DOSE
• Regeneration means replacement by the original tissue while Repair means replacement by connective tissue.
IAEA 3 : Biological effects of ionizing radiation 45
Skin effects
• Following the RS laws (Bergonie and Tribondeau), the most RS cells are those from the basal stratum of the epidermis.
• Effects are:• Erythema: 1 to 24 hours after irradiation of
about 3-5 Gy• Alopecia(*): 5 Gy is reversible; 20 Gy is
irreversible.• Pigmentation: Reversible, appears 8 days
after irradiation.• Dry or moist desquamation: traduces
epidermal hypoplasia (dose 20 Gy). • Delayed effects: teleangiectasia (**),
fibrosis.
Histologic view of the skin
Basal stratum cells, highly mitotic, some of them with
melanin, responsible of pigmentation.
From “Atlas de Histologia...”. J. Boya
(*):alopecia: loss or absence of hair(**): ectasia: swelling of part of the body
IAEA 3 : Biological effects of ionizing radiation 46
InjuryThreshold Dose to
Skin (Sv)
Weeks to Onset
Early transient erythema 2 <<1Temporary epilation 3 3
Main erythema 6 1.5Permanent epilation 7 3Dry desquamation 10 4Invasive fibrosis 10Dermal atrophy 11 >14Telangiectasis 12 >52
Moist desquamation 15 4Late erythema 15 6-10
Dermal necrosis 18 >10Secondary ulceration 20 >6
Skin damagefrom prolongedfluoroscopicexposure
Skin reactions
IAEA 3 : Biological effects of ionizing radiation 47
Skin injuries
IAEA 3 : Biological effects of ionizing radiation 48
Skin injuries
IAEA 3 : Biological effects of ionizing radiation 49
Effects in eye
• Eye lens is highly RS.
• Coagulation of proteins occur with doses greater than 2 Gy.
• There are 2 basic effects:
From “Atlas de Histologia...”. J. Boya
Histologic view of eye:
Eye lens is highly RS, moreover, it is surrounded by highly RS cuboid cells. > 0.155.0
Visual impairment (cataract)
> 0.10.5-2.0Detectable opacities
Sv/year for many years
Sv single brief exposure
Effect
IAEA 3 : Biological effects of ionizing radiation 50
Eye injuries
IAEAInternational Atomic Energy Agency
Part 3: Biological effect of ionizing radiation
Topic 4: Whole body response: acute radiation syndrome
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
IAEA 3 : Biological effects of ionizing radiation 52
Whole body response: adult
Acute irradiation syndrome Chronic irradiation
syndrome
Sur
viva
l tim
e
Dose
Steps:
1. Prodromic (onset of disease)
2. Latency
3. Manifestation
Lethal dose 50 / 30
BONE MARROW GASTRO
INTESTINAL
CNS(central nervous
system)
1-10 Gy
10 - 50 Gy
> 50 Gy
•Whole body clinic of a partial-body irradiation
•Mechanism: Neurovegetative disorder
•Similar to a sick feeling
•Quite frequent in fractionated radiotherapy
IAEA 3 : Biological effects of ionizing radiation 53
Lethal dose 50 / 30
• “Dose which would cause death to 50% of the population in 30 days”.
• Its value is about 2-3 Gy for humans for whole body irradiation.
IAEAInternational Atomic Energy Agency
Part 3: Biological effect of ionizing radiation
Topic 5: Effects of antenatal exposure and delayed effect
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
IAEA 3 : Biological effects of ionizing radiation 55
Effects of antenatal exposure (1)
• As post-conception time increases RS decreases
• It is not easy to establish a cause-effect relation because there are a lot of teratogenic agents, effects are unspecific and not unique to radiation.
• There are 3 kinds of effects: lethality, congenital anomalies and large delay effects (cancer and hereditary effects).
Time
%
Pre-implantation Organogenesis Foetus
LethalityCongenital anomalies
IAEA 3 : Biological effects of ionizing radiation 56
Effects of antenatal exposure (2)
• Lethal effects can be induced by relatively small doses (such as 0.1 Gy) before or immediately after implantation of the embryo into the uterine wall. They may also be induced after higher doses during all the stages during intra-uterine development.
Time
%
Pre-implantation Organogenesis Foetus
Lethality
0.1 Gy
IAEA 3 : Biological effects of ionizing radiation 57
Effects of antenatal exposure (3)
• Mental retardation:
• ICRP establishes that mental retardation can be induced by radiation (Intelligence Quotient score < 100).
• It occurs during the most RS period: 8-25 week of pregnancy.
• Risks of antenatal exposure related to mental retardation are:
Severe mental retardation with a
risk factor of
0.1/Sv
Severe mental retardation with a
risk factor of
0.4/Sv
15-25 week8-15 week
IAEA 3 : Biological effects of ionizing radiation 58
Delayed effects of radiation
• Classification:
• SOMATIC: they affect the health of the irradiated person. They are mainly different kinds of cancer (leukemia is the most common, with a delay period of 2-5 years, but also colon, lung, stomach cancer…)
• GENETIC: they affect the health of the offspring of the irradiated person. They are mutations that cause malformation of any kind (such as mongolism)
IAEAInternational Atomic Energy Agency
Part 3: Biological effects of ionizing radiation
Topic 6: Epidemiology
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
IAEA 3 : Biological effects of ionizing radiation 60
Epidemiology I
• Irradiated populations can be studied by• following cohorts of exposed and non-exposed
people
• back-tracing patients suffering from the disease with regard to possible exposure (case controls)
IAEA 3 : Biological effects of ionizing radiation 61
Epidemiology II
• Irradiated populations are • people exposed from the atomic bomb
explosions
• people exposed during nuclear and other radiation accidents
• patients exposed for medical reasons
• people exposed to natural radiation
• workers in radiation industries
IAEA 3 : Biological effects of ionizing radiation 62
Epidemiology III
• Most valid data come from high dose / high dose rate exposure to low LET radiation, including some radionuclides [iodine 131I], and from high LET internal exposure to a emitters in lung, bone and liver.
IAEA 3 : Biological effects of ionizing radiation 63
Epidemiology IV
• Information is scanty (not much,less than needed) on:
• Consequences of low doses delivered at low dose rates • To detect an increase from a 20% spontaneous cancer
incidence to 25% (corresponding to an exposure to ~1 Sv) > 1300 persons must be studied
• Consequences of external high LET radiation • (neutrons) and several radionuclides
• Presence and influence of confounding factors• especially if different populations are to be compared
IAEA 3 : Biological effects of ionizing radiation 64
Epidemiology V
• Modifying influence of cancer background incidence • does radiation-induced cancer increase at a fixed level
or in proportion to existing cancer additive vs. multiplicative risk model ?
• Is, for example, the risk greater in:• European women which have a higher background
breast tumor rate than Japanese women ?
• Smokers exposed to radon in homes or mines than in non-smokers ?
Detectability limits in Radioepidemiology
Number of people in study and control groups
EF
FE
CT
IVE
D
OS
E
(mS
v)
510
-110010
010
110
110
210
210
410
410
310
310
610 710 810 910 1010 1110
CHERNOBYL DOSES
REGION OF DETECTABILITY
REGION OF UNDETECTABILITY
Theoretical limit of detectability due to statistical causes (90% confidence interval)
IAEA 3 : Biological effects of ionizing radiation 66
High and Low Spontaneous Cancer Rates Incidence/105
Tissue High Low Male / Female Male /Female
Nasopharynx 23.3 9.5 0.2 0.1Esophagus 20.1 8.3 0.5 0.2 Stomach 95.5 40.1 5.2 2.2Colon 35.0 29.6 1.8 1.3Liver 46.7 11.5 0.7 0.3Lung+Bronchus 110.8 29.6 10.3 2.4Skin melanoma 33.1 29.8 0.2 0.2Breast female 103.7 14.6Cervix 53.5 3.0from UNSCEAR 2000
IAEA 3 : Biological effects of ionizing radiation 67
Data on irradiated populations
Population Approximate SizeAtomic bomb survivors Japan: 86 000Atomic tests:Semipalatinsk/Altai 30 000 Marshallese islanders 2 800Nuclear accidents: intervention teams Chernobyl (total) > 200 000
population Chernobyl (>185 kBq /m2 137Cs) 1 500 000population Chelyabinsk (total) 70 000
Medical procedures: low LET iodine treatment and therapy ~ 70 000
chest fluoroscopy 64 000children hemangioma treatment 14 000
high LET thorotrast angiography 4 200Ra-224 treatment 2 800
Prenatal exposure (fetal radiography, atomic bombs) 6 000Occupational exposure: workers nuclear industry (Japan, UK)115 000
uranium miners 21 000radium dial painters 2 500radiologists 10 000
Natural exposure (Chinese, EC and US studies) several 100 000
IAEA 3 : Biological effects of ionizing radiation 68
Populations Studied for Specific Cancers (I)
• Leukemia: atomic bomb survivors, radiotherapy for ankylosing spondylitis and cervix cancer, radiologists, people at the Majak plant, Chelyabinsk and the Techa river, prenatal radio-diagnostics (Oxford survey)
• Lung cancer: atomic bomb survivors, U and other miners in CSSR, Canada, USA, Germany, Sweden
IAEA 3 : Biological effects of ionizing radiation 69
Populations Studied for Specific Cancers (II)
• Breast cancer: atomic bomb survivors, fluoroscopy TB patients, radiotherapy mastitis
• Thyroid cancer: radiotherapy thymus enlargement, tinea capitis skin hemangioma, fallout at Marshall islands, children near the Chernobyl accident
• Liver cancer: Thorotrast angiography
• Osteosarcoma: 224Ra (226Ra) treatment, 226Ra (watch) dial painters.
Excess Solid-Tumor Deaths amongAtomic-Bomb Survivors
IAEA 3 : Biological effects of ionizing radiation 71
Relative Mortality Risks at Different Times After Exposure
0.5
5
1950- 1954
1963- 1966
1959- 1962
1955- 1958
1971- 1974
1967- 1970
1975- 1978
1979- 1982
1
10
20
2
Interval of follow-up Atomic bomb survivors
Est
imat
ed r
elat
ive
risk
at 1
Gy
All cancers except leukaemia (+ 4.8%/y)
Leukaemia ( ~10.7%/y)
IAEA 3 : Biological effects of ionizing radiation 72
Relative Risks of Radon from Indoor Exposure and from Mining
0 100 200 300 400 5000.3
1
0.5
0.6
2
0.4
Radon concentration Bq/m3
Rel
ativ
e ri
sk
miner studies (cohorts)indoor studies (case controls)log-linear fit to indoor studiesestimated from correlation
study in different regions
1.5
IAEA 3 : Biological effects of ionizing radiation 73
Breast Cancer in Women Exposed to Fluoroscopy
Ob
se
rve
d/e
xp
ect
ed
bre
as
t c
an
cers
0 1 2 3 40
1
2
3
4
Mean absorbed dose (Gy)
IAEA 3 : Biological effects of ionizing radiation 74
Thyroid Tumors in Irradiated Children
0 0.05 0.1 0.15 0.2 0.250
2
4
6
8
10
Mean dose (Gy)
Rel
ativ
e ri
sk
Thyroid Cancer
Thyroid benign tumors
IAEA 3 : Biological effects of ionizing radiation 75
Thyroid Cancer Cases in Children after the Chernobyl Accident
86 87 88 89 90 91 92 93 94 95 96 97 980
20
40
60
80
100
Ukraine
Russian Fed.
Belarus
No
of
Cas
es
Children under 15 years of age at diagnosis
IAEA 3 : Biological effects of ionizing radiation 76
Thyroid Cancer in Children in the Chernobyl Region
Region No of Cases before the accident after the accident
Belarus (1977-1985) 7 (1986-1994) 390Ukraine (1981-1985) 24 (1986-1995) 220Russia (Bryansk and Kaluga region only) (1986-1995) 62
The data represent incidences (not mortality) and are preliminary results.Most excess cancers occurred since 1993.Thyroid cancer has a high rate of cure >90%, but many of the cancers found are of the aggressive papillary type.
IAEA 3 : Biological effects of ionizing radiation 77
Risk Estimates from Occupational Exposure
Study Excess relative risk per SvAll cancer Leukemia
UK National RegistryRadiation Workers 0.47 (-0.12-1.20) 4.3 (0.4-13.6) 1,218,000 person years 34 mSv average doseUS Workers -1.0 (<0-0.83 <0 (<0-3.4) 705,000 person years 32 mSv average doseAtomic Bomb Survivors 0.33 (0.11-0.6) 6.2 (2.7-13.8) 2,185,000 person years 251 mSv average dose
IAEA 3 : Biological effects of ionizing radiation 78
Doses and Risks for in Utero Radiodiagnostics
Exposure Mean foetal dose Hered. Disease Fatal cancer (mGy) to age 14 y X Ray Abdomen 2.6 6.2 10-5 7.7 10-5
Barium enema 16 3.9 10-4 4.8 10-4
Barium meal 2.8 6.7 10-5 8.4 10-5
IV urography 3.2 7.7 10-5 9.6 10-5
Lumbar spine 3.2 7.6 10-5 9.5 10-5
Pelvis 1.7 4.0 10-5 5.1 10-5
Computed tomographyAbdomen 8.0 1.9 10-4 2.4 10-4
Lumbar spine 2.4 5.7 10-5 7.1 10-5
Pelvis 25 6.1 10-4 7.7 10-4
Nuclear medicine Tc bone scan 3.3 7.9 10-4 1.0 10-4
Tc brain scan 4.3 1.0 10-5 1.3 10-4
IAEA 3 : Biological effects of ionizing radiation 79
Extrapolation by Additive and Multiplicative Risks Models
An
nu
a l P
rob
ab
i lity
of
de
ath
/10
00 p
ers
on
s
Age Years55 60 65 70 75
15
5
25
35
45
Following exposure to 2 Gy at an age of 45 yearsSpontaneous risks: increase with age:Radiation risks become apparent after a lag period (5) -10 years
Additive risk models: imply constant risk independent of background.
Multiplicative risk models: imply an increase proportional to background risk
IAEA 3 : Biological effects of ionizing radiation 80
Risk Probability Coefficients (ICRP)
Tissue Probability of fatal Cancer (10-2/Sv) Population WorkersBladder 0.30 0.24Bone marrow 0.50 0.40Bone surface 0.05 0.04Breast 0.20 0.16Colon 0.85 0.68Liver 0.15 0.12Lung 0.85 0.68Esophagus 0.30 0.24Ovary 0.10 0.08Skin 0.02 0.02Stomach 1.10 0.88Thyroid 0.08 0.06Remainder 0.50 0.40Total all cancers 5.00 4.00Genetic effects weighted 1.00 0.50
IAEA 3 : Biological effects of ionizing radiation 81
Proportion of Fatal Cancers Attributable to Different Agents
Agent or Class Percentage of all Cancer Disease Best estimate RangeSmoking 31 29 - 33Alcoholic beverages 5 3 - 7Diet 35 20 - 60Natural hormones 15 10 - 20Infection 10 5 - 15Occupation 3 2 - 6Medicines, medical practices 1 0.5 - 2 Electromagnetic radiation 8 5 -10Ionizing (85% from natural radiation*) 4.5Ultraviolet 2.5Lower frequency <1Industrial products <1 <1 - 2Pollution 2 <1 - 4Other ? ?
IAEA 3 : Biological effects of ionizing radiation 82
Tissue risk factor (1)
• RISK FACTOR: The quotient of increase in probability of a stochastic effect and the received dose. It is measured in Sv-1 or mSv-1.
% E
ffe
ct
Dose
dose
probability Risk factor
=
probability
dose
IAEA 3 : Biological effects of ionizing radiation 83
Tissue risk factor (2)
• EXAMPLE: A risk factor of 0.005 Sv-1 for bone marrow (lifetime mortality in a population of all ages from specific fatal cancer after exposure to low doses) means that if 1,000 people would receive 1 Sv to the bone marrow, 5 will die from a cancer induced by radiation.
% E
ffe
ct
Dose
dose
probability Risk factor
=
probability
dose
IAEA 3 : Biological effects of ionizing radiation 84
Indicators of relative organ tissue risk
0.05Remainder
0.01Bone surface
0.01Skin
0.05Thyroid
0.05Oesophagus
0.05Liver
0.05Breast
0.05Bladder
0.12Stomach
0.12Lung
0.12Colon
0.12Bone marrow (red)
0.20Gonads
wTTISSUE OR ORGAN
IAEA 3 : Biological effects of ionizing radiation 85
Summary
• Effects of ionizing radiation may be deterministic and stochastic, immediate or delayed, somatic or genetic
• Some tissues are highly radiosensitive
• Each tissue has its own risk factor
• Risk from exposure may be assessed through such factors
IAEA 3 : Biological effects of ionizing radiation 86
Where to Get More Information (1)
• 1990 Recommendations of the ICRP. ICRP Publication 60. Pergamon Press 1991
• Radiological protection of the worker in medicine and dentistry. ICRP Publication 57. Pergamon Press 1989
• Sources and Effects of Ionizing Radiation. United Nations Scientific Committee on the Effects of Atomic Radiation UNSCEAR 2000 Report to the General Assembly, with Scientific Annexes. New York, United Nations 2000.
IAEA 3 : Biological effects of ionizing radiation 87
Where to Get More Information (2)
• Avoidance of radiation injuries from medical interventional procedures. ICRP Publication 85. Ann ICRP 2000;30 (2). Pergamon
• Manual of clinical oncology 6th edition. UICC. Springer-Verlag. 1994
• Atlas de Histologia y organografia microscopica. J. Boya. Panamericana. 1998
• Tubiana M. et al. Introduction to Radiobiology. London: Taylor & Francis, 1990. 371 pp. ISBN 0-85066-763-1.
Top Related