International Atomic Energy Agency RADIATION PROTECTION IN NUCLEAR MEDICINE Part 1: Biological Effects of Ionizing Radiation
Transcript
Slide 1
International Atomic Energy Agency RADIATION PROTECTION IN
NUCLEAR MEDICINE Part 1: Biological Effects of Ionizing
Radiation
Slide 2
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 2 Objective To become familiar with the mechanisms of
different types of biological effects following exposure to
ionizing radiation and results of epidemiological studies of
exposed population to ionizing radiation. To be aware of the models
used to derive risk coefficients for estimating the detriment
Slide 3
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 3 Contents Basic concepts, cellular effects Deterministic
effects Stochastic effects Effects on embryo and fetus Risk
estimates
Slide 4
International Atomic Energy Agency Part 1. Biological Effects
Module 1.1. Basic Concepts
Slide 5
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 5 1895 X-rays discovered by Roentgen 1896 First skin
burns reported 1896 First use of x-rays in the treatment of cancer
1896 Becquerel: Discovery of radioactivity 1897 First cases of skin
damage reported 1902 First report of x-ray induced cancer 1911
First report of leukaemia in humans and lung cancer from
occupational exposure 1911 94 cases of tumour reported in Germany
(50 being radiologists) Early Observations of the Effects of
Ionizing Radiation
Slide 6
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 6 Information comes from: studies of humans
(epidemiology) studies of animals and plants (experimental
radiobiology) fundamental studies of cells and their components
(cellular and molecular biology) The key to understanding the
health effects of radiation is the interaction between these
sources of information. Effects of Radiation Exposure
Slide 7
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 7 Radiation exposure affects the center of life: the cell
Chromosomes
Slide 8
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 8
Slide 9
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 9 The critical target: DNA
Slide 10
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 10 Interaction of ionizing radiation with DNA DIRECT
ACTION INDIRECT ACTION
Slide 11
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 11 Damage to DNA
Slide 12
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 12 radiation hit cell nucleus! No change DNA mutation
Exposure of the Cell
Slide 13
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 13 DNA Mutation Cell survives but mutated Cancer? Cell
death Mutation repaired Unviable Cell Viable Cell Outcomes after
cell exposure
Slide 14
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 14 How is DNA repaired?
Slide 15
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 15 Altered base Enzyme Glycosylases recognizes lesion and
releases damaged base AP-endunuclease makes incision and releases
remaining sugar DNA-polymerase fills resulting gap but nick remains
DNA ligase seals the nick. Repair completed. DNA has been repaired
with no loss of genetic information
Slide 16
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 16 Repair The human body contains about 10 14 cells. An
absorbed dose of 1 mGy per year (natural sources) will produce
about 10 16 ionizations, which means 100 per cell in the body. If
we assume that the mass of DNA is 1% of the mass of the cell, the
result will be one ionization in the DNA-molecule in every cell in
the body each year.
Slide 17
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 17 order of magnitudes 999 of 1000 lesions are repaired
999 of 1000 damaged cells die (not a major problem as millions of
cells die every day in every person) many cells may live with
damage (could be mutated)
Slide 18
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 18 Cell killing Radiosensitivity 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.
Slide 19
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 19 RADIOSENSITIVITY High RSMedium RSLow RS Bone Marrow
Spleen Thymus Lymphatic nodes Gonads Eye lens Lymphocytes
(exception to the RS laws) Skin Mesoderm organs (liver, heart,
lungs) Muscle Bones Nervous system
Slide 20
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 20 Biological Effects at Cellular Level Possible
mechanisms of cell death: Physical death Functional death Death
during interphase Mitotic delay Reproductive failure Cellular
effects of ionizing radiation are studied by cell survival curves %
survival cells (semi logarithmic) Dose n = targets DqDq D0D0
(threshold) (radiosensitivity) 100%
Slide 21
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 21 Physical LET (linear energy transfer): RS Dose rate:
RS Temperature 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) G1 S G2 M G0 LET LET % survivor cells
Factors Affecting Radiosensitivity
Slide 22
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 22 low LET high LET low LET Absorbed dose Surviving
fraction LET (linear energy transfer) is the amount of energy (MeV)
a particle will loose in traversing a certain distance (m) of a
material. Cell Survival Radiation Quality
Slide 23
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 23 Adapted from Marco Zaider (2000) Ionization
Pattern
Slide 24
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 24 Direct effects Indirect effects Cell death Primary
damage Modified cell Damage to organ Somatic cells Germ cells
Hereditary effects Cancer Leukemia Death of organism Repair
Deterministic effects Stochastic effects Biological Effects
Slide 25
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 25 Timing of Events leading to Radiation Effects
Slide 26
International Atomic Energy Agency Part 1. Biological Effects
Module 1.2. Deterministic Effects
Slide 27
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 27 Effects of Cell Death Effects of Cell Death Dose (mSv)
Probability of death D 100%
Slide 28
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 28 0123456789 10 FREQUENCY ABSORBED DOSE SEVERITY
Diagnostic threshold Threshold dose Most radiosensitive individual
Most radioresistant individual Deterministic Effects
Slide 29
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 29 Cataracts of the lens of the eye 0.5 Gy [ICRP
statement on tissue reactions
(http://www.icrp.org/docs/icrp%20stateme
nt%20on%20tissue%20reactions.pdf)]http://www.icrp.org/docs/icrp%20stateme
nt%20on%20tissue%20reactions.pdf Permanent sterility males 3.5-6 Gy
females 2.5-6 Gy Temporary sterility males 0.15 Gy females 0.6 Gy
dose Severity of effect threshold Threshold Doses for Deterministic
Effects
Slide 30
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 30 Note on Threshold Values Depend on dose delivery mode:
single high dose most effective fractionation increases threshold
dose in most cases significantly decreasing the dose rate increases
threshold in most cases Threshold may differ in different
persons
Slide 31
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 31 Systemic Effects Effects may be morphological and/or
functional Factors: Which Organ Which Dose Effects Immediate
(usually reversible): < 6 months e.g.: inflammation, bleeding.
Delayed (usually irreversible): > 6 months e.g.: atrophy,
sclerosis, fibrosis. Criteria 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.
Slide 32
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 32 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: 1-24 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 about 20 Gy). Delayed effects: teleangiectasia,
fibrosis. DERMIS EPIDERMIS Histologic view of the skin Basal
stratum cells, highly mitotic, some of them with melanin,
responsible of pigmentation. From Atlas de Histologia.... J.
Boya
Slide 33
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 33 Skin Effects Skin damage from prolonged fluoroscopic
exposure
Slide 34
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 34 Skin Effects By handling unshielded syringes and vials
containing radioactive material the threshold dose of skin erythema
will be reached in a short time. Example: The dose rate at the
surface of a vial containing 30 GBq Tc99m is of the order of 2 Gy/h
meaning that the threshold dose will be reached after 2 h of
exposure. This corresponds to 36 s per working day in a year
Slide 35
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 35 Skin Effects Example: After an extravascular injection
of 500 MBq of a Tc99m radiopharmaceutical, the locally absorbed
dose at the injection site might be as high as 5-20 Gy!
Slide 36
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 36 Effects in Eye Eye lens is highly RS. Coagulation of
proteins occurs 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) > 0.1
0.5-2.0 Detectable opacities Sv/year for many years Sv single brief
exposure Effect The ICRP has stated in 2011 that the threshold for
tissue reactions in lens of the eye is 0.5 Gy.
http://www.icrp.org/docs/icrp%20statement%20on%20tissue%20reactions.pdf
http://www.icrp.org/docs/icrp%20statement%20on%20tissue%20reactions.pdf
Slide 37
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 37 Eye Injuries
Slide 38
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 38 Whole Body Response : Adult Acute irradiation syndrome
Chronic irradiation syndrome Survival time Dose Steps: 1.Prodromic
2.Latency 3.Manifestation Lethal dose 50 / 30 BMS (bone marrow) GIS
(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
Slide 39
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 39 Lethal Dose 50/30 It is an expression of the per cent
lethal dose as a function of time. It means: 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.
Slide 40
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 40 Whole Body Exposure Absorbed dose (Gy) Syndrome or
tissue involved Symptoms 1-10Bone marrow syndrome Leucopenia,
thrombopenia, hemorrhage, infections
10-50GastrointestinalDiarrhoea, fever, electrolytic imbalance
>50Central nervous syndrome Cramps, tremor, ataxia, lethargy,
impaired vision, coma
Slide 41
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 41 Whole Body Exposure Absorbed dose (Gy)
TherapyPrognosis 1-10Symptomatic Transfusions of leucocytes and
platelets. Bone marrow transplantation Growth stimu- lating factors
Excellent to uncertain 10-50PalliativeVery poor
>50SymptomaticHopeless Lethality 0-90% 90-100% 100%
Slide 42
International Atomic Energy Agency Part 1. Biological Effects
Module 1.3. Stochastic Effects
Slide 43
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 43 Stochatic Effects of Ionizing Radiation
Slide 44
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 44 Stochatic Effects of Ionizing Radiation Health
consequences of Chernobyl accident 1800 children diagnosed with
thyroid cancer (1998)
Slide 45
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 45 Stochatic Effects of Ionizing Radiation
Slide 46
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 46 Frequency (%) 10 20 30 40 Absorbed dose (Gy) 10 5 0
Genetic Effects
Slide 47
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 47 Genetic Effects Ionizing radiation is known to cause
heritable mutations in many plants and animals BUT intensive
studies of 70,000 offspring of the atomic bomb survivors have
failed to identify an increase in congenital anomalies, cancer,
chromosome aberrations in circulating lymphocytes or mutational
blood protein changes. Neel et al. Am. J. Hum. Genet. 1990,
46:1053-1072
Slide 48
International Atomic Energy Agency Part 1. Biological Effects
Module 1.4. Effects on Embryo and Fetus
Slide 49
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 49 Sensitivity of the Early Conceptus Till early 1980s,
early conceptus was considered to be very sensitive to radiation -
although no one knew how sensitive? Realization that: organogenesis
starts 3-5 weeks after conception In the period before
organogenesis high radiation exposure may lead to failure to
implant. Low dose may not have any observable effect.
Slide 50
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 50 Incidence of Prenatal & Neonatal Death and
Abnormalities Hall, Radiobiology for the Radiologist pg 365
Slide 51
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 51 Pre-Implantation
Slide 52
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 52 Pre-Implant Stage (up to 10 days) Only lethal effect,
all or none Embryo contains only few cells which are not
specialized If too many cell are damaged-embryo is resorbed If only
few killed-remaining pluripotent cells replace the cells loss
within few cell divisions Atomic Bomb survivors - high incidence of
both - normal birth and spontaneous abortion
Slide 53
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 53
Slide 54
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 54 Fetal Radiation Risk There are radiation-related risks
throughout pregnancy which are related to the stage of pregnancy
and absorbed dose Radiation risks are most significant during
organogenesis and in the early fetal period somewhat less in the
2nd trimester and least in the third trimester LessLeast Most
risk
Slide 55
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 55 Radiation-Induced Malformations Malformations have a
threshold of 100-200 mGy or higher and are typically associated
with central nervous system problems Fetal doses of 100 mGy are not
reached even with 3 pelvic CT scans or 20 conventional diagnostic
x-ray examinations These levels can be reached with
fluoroscopically guided interventional procedures of the pelvis and
with radiotherapy
Slide 56
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 56 Central Nervous System Effects During 8-25 weeks
post-conception the CNS is particularly sensitive to radiation
Fetal doses in excess of 100 mGy can result in some reduction of IQ
(intelligence quotient) Fetal doses in the range of 1000 mGy can
result in severe mental retardation particularly during 8-15 weeks
and to a lesser extent at 16-25 weeks
Slide 57
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 57 Heterotopic gray matter (arrows) near the ventricles
in a mentally retarded individual occurring as a result of high
dose in-utero radiation exposure
Slide 58
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 58 Effects on Embryo and Fetus
Slide 59
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 59 AgeThreshold for lethal effects (mGy) Threshold for
malformations (mGy) 1 day100No effect 14 days250- 18 days500250 20
days>500250 50 days>1000500 50 days to birth >1000>500
Effects on Embryo and Fetus
Slide 60
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 60 Leukemia and Cancer Radiation has been shown to
increase the risk for leukemia and many types of cancer in adults
and children Throughout most of pregnancy, the embryo/fetus is
assumed to be at about the same risk for carcinogenic effects as
children
Slide 61
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 61 Leukemia and Cancer The relative risk may be as high
as 1.4 (40% increase over normal incidence) due to a fetal dose of
10 mGy Individual risk, however, is small with the risk of cancer
at ages 0-15 being about 1 excess cancer death per 1,700 children
exposed in utero to 10 mGy
Slide 62
International Atomic Energy Agency Part 1. Biological Effects
Module 1.5. Risk Estimates
Slide 63
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 63 Risk Estimates Risk = probability of effect Different
effects can be looked at - one needs to carefully look at what
effect is considered: E.g. Thyroid cancer mortality is NOT
identical to thyroid cancer incidence!!!! Risk estimates usually
obtained from high doses and extrapolated to low doses
Slide 64
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 64 Epidemiological Data: Hiroshima-Nagasaki Patients with
ancylosing spondylitis cervical cancer tuberculosis mastitis tinea
capitis thymus enlargement thyrotoxicosis hemangiomas and more may
come Chernobyl Techa river Semiplatinsk Nevada ..
Slide 65
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 65 Populations used in the UNSCEAR Reports
Slide 66
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 66 How to Use Epidemiological Data to Estimate Radiation
Risks at Low Doses?
Slide 67
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 67 Dose-Response Curve Frequency of leukemia (cases/1
miljon) Equivalent dose (mSv)
Slide 68
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 68 Mortality of the Atomic Bomb Survivors Dose response
curve for Solid Cancer The dose response is linear up to about 3 Sv
with a slope of 0.37 ERR/Sv The excess lifetime risk per Sv for
those exposed at age 30 is estimated at 0.10 and 0.14 for males and
females respectively The lowest dose at which there is a
statistically significant excess risk is shown to be 50 mSv Pierce
DA et al, Rad Res 1996; 146:1-27
Slide 69
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 69 Latest news from the Hiroshima-Nagasaki Cohort Extra
years 1986-1990 There are now 10 500 survivors with DS86-dosimetry
out of a total population of 86 572, who were irradiated 44% had
died by the end of 1990. The data is incomplete in that deaths in
the first five years are not included. 7 827 have died from cancer,
there being 420 excess cancer deaths. 1945-19501950-90 (1986-90)
Leukemia? 87 (3) Solid cancer?335 (88)
-------------------------------------------------------------------
420 Risk for children/Risk for adults = 1.4 - 1.7
Slide 70
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 70 Radiation Risks Linear-Quadratic Model
Slide 71
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 71 What happens at the low-dose end of the graph?
a)Linear extrapolation b)Threshold dose c)Lower risk per dose for
low doses d)Higher risk per dose for for low doses
Slide 72
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 72 Low doses: 15% incidence of genetic abnormalities 4-
10% intrauterine growth retardation 4% incidence of major
malformation 2- 4%
Slide 89
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 89 Probability of bearing healthy children as a function
of radiation dose
Slide 90
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 90 Approximate fetal whole body dose (mGy) from common
nuclear medicine procedures done in early and late pregnancy
ProcedureActivity (MBq) Early 9 months Tc-99m Bone scan Lung V/Q
scan Liver colloid Thyroid scan Renal DTPA Red Cell 750 240 300 400
750 930 4.7 0.9 0.6 4.4 9.0 6.0 1.8 0.9 1.1 3.7 3.5 2.5 I-123
Thyroid uptake 300.60.3 I-131 Thyroid uptake 0.550.040.15
Slide 91
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 91 Doses and Risks for in Utero Radiodiagnostics Exposure
Mean fetal dose Hered. Disease Fatal cancer (mGy) to age 14 y X-ray
Abdomen2.66.2 10 -5 7.7 10 -5 Barium enema 163.9 10 -4 4.8 10 -4
Barium meal2.86.7 10 -5 8.4 10 -5 IV urography3.27.7 10 -5 9.6 10
-5 Lumbar spine3.27.6 10- 5 9.5 10 -5 Pelvis1.74.0 10 -5 5.1 10 -5
Computed tomography Abdomen8.01.9 10 -4 2.4 10 -4 Lumbar
spine2.45.7 10 -5 7.1 10 -5 Pelvis256.1 10 -4 7.7 10 -4 Nuclear
medicine Tc bone scan3.37.9 10 -4 1.0 10 -4 Tc brain scan4.31.0 10
-5 1.3 10 -4
Slide 92
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 92 Comment on Fetus/Embryo Fetus/embryo is more sensitive
to ionizing radiation than the adult human Increased incidence of
spontaneous abortion a few days after conception Increased
incidence Mental retardation Microcephaly (small head size)
especially 8-15 weeks after conception Malformations: skeletal,
stunted growth, genital Higher risk of cancer (esp. leukemia) Both
in childhood and later life
Slide 93
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 93 Scale of Radiation Exposures Annual Background CT scan
Bone scan Typical Radiotherapy Fraction
Slide 94
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 94 Example for Risk Calculation Assume Risk of 0.05 per
Sv 1,000 people are exposed to 5 mSv/y for 20 y Expected additional
cancer deaths is 0.05 [cancers/Sv]x0.005[Sv/y]x20[y]x1,000[people]
= 5 additional cancer deaths due to radiation (5/1000) General
population: 23% (230/1000) of all deaths due to cancer (difficult
to ascertain 5 additional ones caused by radiation) Calculations
become more complex for individual tissue exposures vs. whole body
exposures
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 96 Examination Radiopharmaceutical Effective dose Risk
(mSv) (%) Myocardium Tl-201 chloride 23 0.12 Bone Tc-99m MDP 3.6
0.018 Thyroid Tc-99m pertechnetate 1.1 0.006 Lungs Tc-99m MAA 0.9
0.005 Kidney clearance Cr-51 EDTA 0.01 0.00005 Radiation Risks in
Nuclear Medicine
Slide 97
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 97 Average Annual Risk of Death in the UK from Industrial
Accidents and from Cancers due to Radiation Work From L Collins
2000 These figures can be compared to an estimate of 1 in 17000 for
1.5 mSv/year received by radiation workers
Slide 98
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 98 Comparison of Radiation Worker Risks to Other Workers
Mean death rate 1989 (10 -6 /y) Trade40 Manufacture60 Service40
Government90 Transport/utilities240 Construction320 Agriculture 400
Mines/quarries430 Safe industries 2 mSv/y (100 mSv over a lifetime)
max permissible exposure (20 mSv/year or 1000 mSv over a lifetime
max permissible exposure (20 mSv/year or 1000 mSv over a
lifetime
Slide 99
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 99 The following activities are associated with a risk of
death that is 1/1000000 10 days work in a nuclear medicine
department smoking 1.4 cigarette living 2 days in a polluted city
traveling 6 min in a canoe 1.5 min mountaineering traveling 480 km
in a car traveling 1600 km in an airplane living 2 months together
with a smoker drinking 30 cans of diet soda Risks
Slide 100
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 100 Expected reduction of life Unmarried man3500 days
Smoking man2250 days Unmarried woman1600 days 30% overweight1300
days Cancer 980 days Construction work 300 days Car accident 207
days Accident at home 95 days Administrative work 30 days
Radiological examination 6 days Risks
Slide 101
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 101 Questions??
Slide 102
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 102 Discussion A woman was referred to a bone scan. After
the examination she turned out to be pregnant at a very early
stage. She is extremely worried and wants to have an abortion.
Discuss how to act.
Slide 103
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 103 Discussion Dose fractionation results in: increased
radiation sensitivity for photons? decreased radiation sensitivity
for photons? decreased radiation sensitivity for heavy charged
particles? increased radiation sensitivity for heavy charged
particles?
Slide 104
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 104 Discussion A patient (radiobiologist) wants to know
the radiation risk he will suffer in an examination of the cerebral
blood flow (1000 MBq 99m Tc). What to answer?
Slide 105
Nuclear Medicine Part 1. Biological effects of ionizing
radiation 105 Where to Get More Information Other sessions Part 2
Radiation Physics Further readings WHO/IAEA. Manual on Radiation
Protection in Hospital and General Practice. Volume 1. Basic
requirements ICRP publications (41, 60, 84) UNSCEAR reports ALPEN
E.L Radiation Biophysics. Academic Press, 1998 RUSSEL, J.G.B.,
Diagnostic radiation, pregnancy and termination, Br. J. Radiol. 62
733 (1989) 92-3.