IAEA Standard Syllabus Course on Radiation Protection in Diagnostic and Interventional Radiology
RADIATION PROTECTION IN
DIAGNOSTIC AND
INTERVENTIONAL RADIOLOGY
L 0. Principles of Radiation Protection and
Motivation for the Course
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International Atomic Energy Agency
Introduction
• Subject matter motivation for radioprotection
and quality assurance in diagnostic and
interventional radiology
• Give an overview of different contributions of
radiation exposure, the principles of
radiation protection
• Specifity of the medical exposure
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Is there
RADIATION
in this room?
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Radiation - We live with
Natural Radiation: Cosmic rays, radiation within our
body, in food we eat, water we drink, house we live
in, lawn, building material etc.
Human Body: K-40, Ra-226, Ra-228
e.g. a man with 70 kg wt.
140 gm of K
140 x 0.012%=
0.0168 gm of K-40
0.1 Ci of K-40
24,000 photons emitted/min
(T1/2 of K-40 = 1.3 billion yrs)
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K-40 Estimate for Lean Body Mass
• Body weight = Fat + lean body mass
• K-40 directly related to lean body mass
• Whole body counter used
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Radiation - We live with
Earth: Top 1m of 0.1 acre garden
=1200 kg of K of which K-40 =1.28 Kg
= +3.6 Kg of Th + 1 Kg Ur
μGy/yr
New Delhi, India
700
Bangalore, India
825
Bombay, India
424
Kerala, India (in narrow
Coastal strip)
4000
Ramsar, Iran
10000
Guarapari, Brazil
8760
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Radiation - We live with
Food
Radioactive levels (Bq/kg)
Daily intake
(g/d)
Rice
Wheat
Pulses
Ra-226
Th-228
Pb-210
K-40
150
270
60
0.126
0.296
0.233
0.267
0.270
0.093
0.133
0.133
0.115
62.4
142.2
397.0
Other
Vegetables
70
0.126
0.167
--
135.2
Leafy
Vegetables
15
0.267
0.326
--
89.1
Milk
90
--
--
--
38.1
1370
0.067
0.089
0.063
65.0
Composite
Diet
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Dose equivalent=0.315 mSv/yr
Total dose from Natural sources = 1.0 to 3.0 mSv/yr
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Radiation from Natural Sources
• Normally 1-3 mSv/year
• In areas of high background, 3-13 mSv/year
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DO WE NEED
RADIATION
PROTECTION ?
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Drinking Hot Coffee
Excess Temperature = 60º - 37 = 23º
1 sip = 3ml
3x 23 = 69 calories
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Lethal Dose= 4Gy
LD 50/60 = 4 Gy
For man of 70 kg
Energy absorbed = 4 x 70 = 280 Joules
= 280/418= 67 calories
= 1 sip
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SO WE NEED
RADIATION
PROTECTION
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Radiation
We live with
1-3 mSv
Can kill
4000 mSv
Where to stop, where is the safe point?
What are the effects of radiation?
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What can radiation do?
Death
Cancer
Skin Burns
Cataract
Infertility
Genetic effects
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CAN X RAYS
CAUSE
DEATH?
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Effect
Deterministic effects
Cataract
infertility
erythema
epilation
Dose
500 mSv cataract
150 mSv for sterility (temporary-males)
2500 mSv for ovarian
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OBJECTIVES OF RADIATION
PROTECTION
• PREVENTION of deterministic effect
• LIMITING the probability of stochastic effect
HOW? Up to what point?
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Optimization
• Optimization balances diagnostic image
quality with dose to the patient.
• High dose >> High image quality
• Low dose may imply low image quality
• However, there are a range of doses where
image quality is clinically acceptable– want
to be in that range
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Optimizaiton
• Optimization is not ALARA
• A certain amount of radiation is needed to
provide the clinical image quality necessary
for diagnostic purposes
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Which Exposure is Optimum?
6.0 mGy
1.5 mGy
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3.0 mGy
0.6 mGy
Little difference in
noise between 6
and 3 mGy,
therefore 6 mGy is
too high.
0.6 mGy too noisy.
Optimum between
1.5 and 3.0 mGy.
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OPTIMIZATION
principle
To what extent OPTIMIZATION ?
Over-stretching OPTIMIZA …………………… TION
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Features of some epidemiological studies of
radiation-induced cancer risks
Life Span Study
(LSS) of
Japanese atomic
bomb survivors
Parameter (Shimizu et al)
Massachusetts
Ankylosing
tuberculosis patients
Spondylitis
given chest
Study (ASS) fluoroscopies
(Weiss et al) (Boice et al)
Children in
Israel irradiated
for ringworm
of the scalp
(Ron et al)
UK National Registry for
Radiation Workers
(Kendall et al)
Population 75991
14109
size
(with DS86 doses)
2573
10834
95217
Period of 5-55 years
Up to over
follow-up following exposure 50 years
(mean 25.2
years)
Up to over 50 years
Up to 32 years
Up to 40 years
(mean 30 years)
(mean 26 years)
Under 15 to over 40
0-15 years
Ranges of:
(a) ages at All
exposure
(b) sexes Similar numbers of
males and females
© ethnic Japanese
groups
Setting in War
which
exposure IAEA
was received
Virtually all
 15 years
83.5% male
18-64 years
Female
Similar number of 92% male
males and females
Western (UK) Western (N. American) African and Asian Western (UK)
Medical:ther- Medical:diagnostic
Medical:therapy Occupational
apy for nonfor non-malignant
malignant
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disease
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Features of some epidemiological studies of
radiation-induced cancer risks (cont.)
Parameter
Range of
organs
irradiated
Life Span Study
(LSS) of
Japanese atomic
bomb survivors
(Shimizu et al)
Massachusetts
Ankylosing
tuberculosis patients
Spondylitis
given chest
Study (ASS) fluoroscopies
(Weiss et al) (Boice et al)
Children in
Israel irradiated
for ringworm
of the scalp
(Ron et al)
All
All (but
mainly those
in proximity
to spine
mainly brain,
bone marrow,
thyroid, skin
and breast
All
Brain, thyroid &
skin doses:
individual basis
Individual whole-body
external doses
Brain: 0-6 Gy
(mean 1.5 Gy)
Thyroid:0-0.5 Gy
(mean 0.09 Gy)
High
Mainly 0-0.5 Sv
(mean 0.034 Sv)
Low
Low-LET
Mainly low-LET
Mainly breast & lung
Availability Organ doses:
Mean organ Organ doses:
of dose
individual basis doses: indiv. Individual basis
estimates
only for red
bone marrow
at present
Range dose Mainly 0-4 Gy Mainly 0-20 Gy Mainly 0-3 Gy
Dose rate
High
Radiation
Quality
Mainly low-LET Low-LET
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High
High, but highly
fractionated
Low-LET
Introduction to Radiation Protection in Diagnostic Radiology
UK National Registry
for Radiation Workers
(Kendall et al)
26
Dose Limits (ICRP 60)
Effective dose
Annual equivalent
dose to
• Lens of eye
• Skin
• Hands & Feet
Occupational
Public
20 mSv/yr averaged*
over 5 yrs.
1 mSv in a yr
150 mSv1
500 mSv
500 mSv
15 mSv
50 mSv
* with further provision that dose in any single yr > 30 mSv (AERB)
and =50 mSv (ICRP)
N.B.: M.P.D. 1931 = 500 mSv, 1947=150 mSv, 1977=50 mSv &
in 1990=20 mSvICRP
1In
a statement (Statement on Tissue Reactions Approved by the Commission on April 21, 2011) proposed a
limit of 20 mSv/yr, averaged over 5 years, not exceeding 50 mSv at any single year .
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Changes in Dose Limit (ICRP)
(Safe levels)
mSv
500
400
300
200
100
0
1931
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1947
1977
1990
Year
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WHAT IS
BASIS FOR
DOSE LIMITS?
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Epidemiological studies have proven that there is
an increased risk for cancer following exposure to
radiation
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WHY
REDUCTION IN
DOSE LIMITS?
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PRINCIPLES
OF
RADIATION
PROTECTION
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1. Justification of practices
2. Optimization of protection by
keeping exposure as low as
reasonably achievable
3. Dose limits for occupational
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HOW TO APPLY
THESE PRINCIPLES IN
DIAGNOSTIC RADIOLOGY?
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RADIOGRAPHY
How much time one works with radiation?
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Radiation ON Time
Workload=100 exposures/day
CxR = 50x50 m sec = 2500 = 2.5
LS = 50x800 m sec = 40000=40s
Total time = 45 sec/day
Not greater than 1 min/day
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Staff Doses
Dose limit ICRP = 20 mSv/yr.
Radiography work  0.1 mS/yr.
i.e. 1/200th of
dose limit
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Radiation Doses in Radiological Exam.
(as multiple of chest X ray)
mSv
.05
0.15
0.49
0.92
1.0
1.22
1.4
1.5
1.7
2.15
2.59
3.0
3.61
3.67
3.8
4.0
4.36
6.0
6.8
7.13
7.69
9.0
Relative Dose Received
Arm, head,ankle & foot (1)
Head & Neck (3)
Head CT (10)
Thoracic Spine (18)
Mammography, Cystography (20)
Pelvis (24)
Abdomen, Hip, Upper & lower femur (28)
Ba Swallow (30)
Obsteric abdomen (34)
Lumbo-sacral area (43)
Cholangiography (52)
Lumber Myelography (60)
Lower abdomen CT male (72)
Upper Abdomen CT (73)
Ba Meal (76)
Angio-head, Angio-peripheral (80)
Urography (87)
Angio-abdominal (120)
Chest CT (136)
Lower Abd. CT fem. (142)
Ba enema (154)
Lymphan. (180)
0
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50
100
number of chest X rays
150
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200
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IS IT POSSIBLE TO GET
DETERMINISTIC EFFECTS IN
RADIOGRAPHIC WORK ?
For staff, for patient..??
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Radiography
Risk of
Death
Skin burn
Infertility
Cataract
Cancer
Genetic effect
Staff
No
No
No
No
U
U
Patient
No
No
No
No
U
U
Public
No
No
No
No
U
U
U: unlikely
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FLUOROSCOPY
AND
CT
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Fluoroscopy and CT
Barium study: 3-6 min/pt x 8 patients/d
=40 min/d
ANGIOGRAPHY
• Diagnostic = 50 min/d
• Therapeutic = 2-5 hr/d
CT
= 10-45 min/d
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Fluoroscopy (excl. inv angio)
Risk of
Death
Skin burn
Infertility
Cataract
Cancer
Genetic effect
Staff
No
No
No
No
U
U
Patient
No
No
No
No
U
U
Public
No
No
No
No
U
U
U: unlikely
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Summary
1.
2.
3.
4.
5.
6.
Radiation we live with
Radiation that can be lethal
Radiation effects
Dose limits
Principles of protection
Application of protection principles in
diagnostic radiology
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