Radiation Protection

1. Principles Of Radiation Protection
Musa Joya
Radiology Department, Kabul University of Medical
Sciences

2. 2
Table of Content
 Concept and aims of Radiation Protection (RP)
Relevant organizations in RP (ICRP, IAEA and UNSCEAR)
 System of RP
• Justification of practices
• Limitation of doses
• Optimization of protection
 Occupational, medical and public exposures
 Dose limits

3. 3
What can radiation do?
Death
Cancer
Skin Burns
Cataract
Infertility
Genetic effects

4. 4
What can radiation do?
Deterministic effects
death, skin burns, cataract,
infertility
Stochastic effects
cancer, genetic effects

5. 5
1.Concepts and aims of radiation protection
• Radiation Protection (RP) is a tool to protect health
against the risks generated by the use of ionizing
radiation
• Always consider BENEFITS Vs RISKS

6. The need for protection applies to all
dose levels
• It is generally assumed that even very small
doses of ionizing radiation can potentially be
harmful (linear no threshold hypothesis)
• Therefore, persons must be protected from
ionizing radiation at all dose levels
6

7. 7
Aims of radiation protection
• Deterministic effects
• RP aims at PREVENTING
them.
• Stochastic effects
• RP aims at REDUCING them.

8. International system of radiation protection
Relevant organizations in RP (ICRP, IAEA and
UNSCEAR)

9. 9
How the system works?

10. 10
THE SCIENTIFIC BASIS OF THE STANDARDSTHE SCIENTIFIC BASIS OF THE STANDARDS
ICRP
IAEAUNSCEAR
Non-governmental
Governmental
Principles
Recommendations
Effects Standards

11. 11
Relevant organizations in radiation protection: ICRP,
IAEA, UNSCEAR
• ICRP provides recommendations
• IAEA establishes standards of safety and
provides for the application of the standards
• UNSCEAR studies the effects of atomic
radiation

12. 12
ICRP (I)
• ICRP (http://www.icrp.org)
• In preparing its recommendations, ICRP considers
the fundamental principles and quantitative bases
upon which appropriate radiation protection
measures can be established, while leaving to the
various national protection bodies the responsibility
of formulating the specific advice, codes of practice,
or regulations that are best suited to the needs of
their individual countries.

13. 13
• ICRP (http://www.icrp.org)
• ICRP offers its recommendations to regulatory and
advisory agencies and provides advice intended to
be of help to management and professional staff
with responsibilities for radiation protection. While
ICRP has no formal power to impose its proposals
on anyone, in fact legislation in most countries
adheres closely to ICRP recommendations.

14. 14
• United Nations Scientific Committee for the
Effects of the Atomic Radiation
• They elaborate the “UNSCEAR reports” to United
Nations General Assembly about use and effects
of atomic radiation.
Relevant organizations in radiation protection:
UNSCEAR

15. 15
• An independent intergovernmental, science
and technology-based organization, in the
United Nations family, that serves as the global
focal point for nuclear cooperation
• Statutory Objectives: to seek, to accelerate
and enlarge the contribution of atomic energy
to …. health …. throughout the word
Relevant organizations in radiation protection: IAEA
(I)
IAEA (http://www.iaea.org)

16. 16
Statutory functions with regard to safety:
• to establish standards of safety for the
protection of health
• to provide for the application of these
standards …. at the request of a state
Relevant organizations in radiation protection: IAEA
(II)

17. 17
• Justification of practices
• Optimization of protection
• Limitation of doses
Systems of radiation protection

18. 18
Justification of a practice
• Justification means that any
exposure produces sufficient
benefit to offset the radiation harm
that it might cause.
• Thus, if the exposure has not any
benefit it is not justified.

19. 19
Optimization of protection
• Optimization includes the
criterion: doses should be “as
low as reasonably achievable”,
• Optimization means that
minimum risk and maximum
benefits should be achieved

20. 20
As Low As Reasonably Achievable
• refers to the continual application of
the optimization principle in the
day-to-day practice.

21. 21
Limitation of doses
• The normal exposure of individuals shall be restricted
so that neither the total effective dose nor the total
equivalent dose to relevant organs or tissues, exceeds
any relevant dose limit, except in special circumstances
•
• Dose limits shall not apply to medical exposures from
authorized practices.

22. International system of radiation protection
Types of exposure

23. 1. Occupational exposure
Defined by the ICRP as:
•Radiation exposures of workers incurred as a
result of their work,
•Doctors, Radiologists, physicists,
dosimetrists, radiography technicians,
nurses, miners etc.

24. 2. Public exposure
• Includes all public exposures other than occupational
or medical exposures, and covers a wide range of
sources of which natural sources are by far the largest
Public exposure in a radiology facility would include
exposure:
• to persons who may happen to be close to or within
the facility and potentially subject to radiation
penetrating the walls of an X ray room

25. 3. Medical exposure
• Medical exposures are intentional exposures for the diagnostic or
therapeutic benefit of the patient
• They are a very significant and increasing source of exposure
• Advanced countries have shown an increase of 58 % in diagnostic
exposures between the UNSCEAR 2000 and 2008
• CT was by far the greatest contributor, being 7.9 % of examinations,
but 47 % of dose
• For the whole world population, the annual effective dose per person
from medical sources is 0.62 mSv compared to 2.4 mSv for natural
sources
• This rapid growth emphasises the need for effective implementation
of the radiation protection principles of justification and optimization

26. Medical exposure is divided into three components:
• patient exposure
• biomedical research exposure
• carers and comforters exposure
An individual person may be subject to one or more of
these categories of exposure, but for radiation
protection purposes each is dealt with separately
3. Medical exposure

27. International system of radiation protection
Dose limits

28. 28
Dose limits (occupational exposure)
• The occupational exposure of any worker should be
controlled so that the following limits be not exceeded:
500 mSvThe hands and feet
500 mSvThe skin
150 mSvThe lens of the eye
Annual equivalent dose in:
20 mSv per year, averaged over
defined periods of 5 years
50 mSv in any single year
Effective dose
Occupational dose limitApplication

29. 29
Dose limits (public)
50 mSvThe skin
15 mSvThe lens of the eye
Annual equivalent dose in:
1 mSv in a year (*)Effective dose
Public dose limitApplication
(*) In special circumstances, an effective dose of up to 5 mSv in a
single year provided that the average dose over five consecutive
years does not exceed 1 mSv per year.

30. Basic framework of radiation protection
Recommended dose limits in planned exposure situations
(ICRP 103)
Type of limit Occupational Public
Effective dose 20 mSv per year, averaged over
defined periods of 5 yearse
1 mSv in a yearf
Annual equivalent dose in:
Lens of the eyeb
20 mSv 15 mSv
Skinc,d
500 mSv 50 mSv
Hands and feet 500 mSv –
a
Limits on effective dose are for the sum of the relevant effective doses from external exposure in the
specified time period and the committed effective dose from intakes of radionuclides in the same period
For adults, the committed effective dose is computed for a 50-year period after intake, whereas
for children it is computed for the period up to age 70 years
b
this limit is a 2011 ICRP recommendation
c
The limitation on effective dose provides sufficient protection for the skin against stochastic effects
d
Averaged over 1 cm2
area of skin regardless of the area exposed
e
With the further provision that the effective dose should not exceed 50 mSv in any single year
Additional restrictions apply to the occupational exposure of pregnant women
f
In special circumstances, a higher value of effective dose could be allowed in a single year, provided that
the average over 5 years does not exceed 1 mSv per year

31. OCCUPATIONAL EXPOSURES
Methods of reducing occupational exposure
Reduction of staff and public dose follows the basic principles
of time, distance, and shielding which are:
@Restrict the time: the longer the exposure, the greater the cumulative
dose
@Ensure that the distance between a person and the X ray source is kept
as large as practicable. Radiation from a point source follows the inverse
square law
►Employ appropriate measures to ensure that the person is shielded
from the source of radiation. High atomic number and density materials such
as lead or steel are commonly used for facility shielding
It is not always necessary to adopt all three principles. There will be occasions
when only one or two should be considered, but equally there will also be
instances when application of the ALARA principle requires the use of all three

32. 4: International system of radiation protection 32
Where to Get More Information
• International Basic Safety Standards for Protection Against
Ionizing Radiation and for the Safety of Radiation Sources. 115,
Safety Standards. IAEA, February 1996.
• ICRP 73, Radiological Protection and Safety in Medicine. Annals
of the ICRP, Vol. 26, Num. 2, 1996. Pergamon. UK.
• 1990 Recommendations of the International Commission on
Radiological Protection. ICRP 60. Annals of the ICRP, Vol. 21,
No. 1-3. Pergamon. UK.
• 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.