IAEA
RADIATION PROTECTION IN NUCLEAR MEDICINE
PART 3. PRINCIPLES OF RADIATION PROTECTION, THE INTERNATIONAL
FRAMEWORK AND REGULATORY REQUIREMENTS
1.
BASIC PRINCIPLES
The main objective of radiation protection (RP) is to avoid the deterministic effects by
keeping doses below the relevant threshold and to reduce the probability of
stochastic effect as much as is reasonably achievable. This shall be achieved by the
following requirements:
 Justification of practices (BSS)
“2.20. No practice or source within a practice should be authorized unless the
practice produces sufficient benefit to the exposed individuals or to society to offset
the radiation harm that it might cause; that is: unless the practice is justified, taking
into account social, economic and other relevant factors.“
 Dose limitation (BSS)
“2.23 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, caused by
the possible combination of exposures from authorized practices, exceeds any
relevant dose limit specified, except in special circumstances provided for in the
Standards. Dose limits shall not apply to medical exposures from authorized
practices.”
 Optimization of protection and safety (BSS)
“2.24. In relation to exposures from any particular source within a practice, except
for therapeutic medical exposures, protection and safety shall be optimized in order
that the magnitude of individual doses, the number of people exposed and the
likelihood of incurring exposures all be kept as low as reasonably achievable,
economic and social factors being taken into account, within the restriction that the
doses to individuals delivered by the source be subject to dose constraints. “
2.
INTERNATIONAL BASIC SAFETY STANDARDS
Several international organizations are concerned with the promotion of radiation
protection. The primordial organization is the International Commission on
Radiological Protection (ICRP) which, together with its sister organization, the
International Commission on Radiation Units and Measurements (ICRU), was
established in 1928 by the Second International Congress of Radiology.
The United Nations Scientific Committee on the Effects of Atomic Radiation
(UNSCEAR) regularly reviews the current status of the human radiation environment
and the current knowledge of radiation effects and radiation risks. The work of
UNSCEAR is an important base for the recommendations of the ICRP and the
program planning of the international organizations.
The Food and Agriculture Organization (FAO), International Atomic Energy
Agency (IAEA), International Labour Organization (ILO), and the World Health
Organization (WHO), which are organizations within the United Nations system, all
have offices handling matters concerning radiation protection. Together and in
cooperation with the Nuclear Energy Agency of the OECD, and the Pan American
Health Organization (PAHO), those Organizations formulated the International Basic
Safety Standards for Protection against Ionizing Radiation and for the Safety of
Radiation Sources for use by the appropriate regulatory authorities in the respective
organization’s Member States, and also to provide general guidance for
organizations representing employers or workers. The Standards are based on
estimates on radiation health effects made by UNSCEAR and the radiation protection
principles and recommendations of ICRP.
The purpose of the Standards is to establish basic requirements for protection
against the risk associated with exposure to ionizing radiation and for the safety of
radiation sources that may deliver such exposure. The Standards lay down basic
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RADIATION PROTECTION IN NUCLEAR MEDICINE
PART 3. PRINCIPLES OF RADIATION PROTECTION, THE INTERNATIONAL
FRAMEWORK AND REGULATORY REQUIREMENTS
principles and indicate the different aspects that should be covered by an effective
radiation protection program. The Standards are aimed to serve as a practical guide
for public authorities and services, employers and workers, specialized radiation
protection bodies, enterprises and safety and health committees.
The Standards apply to all practices, sources of radiation within practices
and interventions which are undertaken in a Member State that adopts the Standards
or are undertaken by States with the technical assistance of the sponsoring
organizations.
A practice may be exempted from the requirements of the Standards if the
effective dose < 10Sv in a year, the collective effective dose committed by one year
of practice < 1manSv or if exemption is the optimum option.
Principal requirements
The Standards define the basic obligations in radiation protection. These include
notification and authorization (registration or licensing) of a practice. The main
responsibility for radiation protection and safety lies with the registrant and the
licensee but also with the employer. The requirements include justification, dose
limitation, dose constraints and guidance levels for medical exposure, and
optimization of protection and safety.
The licensee shall ensure that a high standard of safety is achieved by
fostering and maintaining a safety culture, by establishing a quality assurance
program, by ensuring that the staff have the necessary qualifications to perform their
duties and to have qualified experts available for providing advice on the observance
of the Standards.
An authorized practice shall also fulfil technical requirements such as the
security of sources to prevent theft and unauthorized use and to ensure that a
multilayer (defence in depth) system of provisions for protection is applied to sources
such that a failure at one layer is compensated for in subsequent layers.
The licensee is also responsible for verification of safety by performing safety
assessments, establish a monitoring programme and maintain records specified by
the Standards.
Detailed requirements
The detailed requirements include the provisions for the following types of exposures:
Occupational exposure
All exposures of workers incurred in the course of their work, with the exception of
exposures excluded from the Standards and exposures from practices or sources
exempted by the Standards.
Medical exposure
Exposure incurred by patients as part of their own medical or dental diagnosis or
treatment; by persons, other than those occupationally exposed, knowingly while
voluntarily helping in the support and comfort of patients; and by volunteers in a
programme of biomedical research involving their exposure.
Public exposure
Exposure incurred by members of the public from radiation sources, excluding any
occupational or medical exposure and the normal local natural background radiation
but including exposure from authorized sources and practices and from intervention
situations.
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RADIATION PROTECTION IN NUCLEAR MEDICINE
PART 3. PRINCIPLES OF RADIATION PROTECTION, THE INTERNATIONAL
FRAMEWORK AND REGULATORY REQUIREMENTS
Potential exposure
Exposure that is not expected to be delivered with certainty but that may result from
an accident at a source or owing to an event or sequence of events of a probabilistic
nature, including equipment failures and operating errors.
Emergency exposure
Chronic exposure
Exposure persisting in time
3.
REGULATORY CONTROL
Radiation protection should be a service by society for society. Almost every country
in the world has a national radiation protection organization or service although in
many cases without adequate resources and financial support. The statutory
structure for radiation protection should be on three levels:
 Laws, which provide the legal basis for regulating radiation protection;
 Regulations, which establish general principles and requirements; and
 Codes of practice, which provide instructions for the handling and safe use of
various sources of ionizing radiation.
The law should establish or designate a Regulatory Authority with a clearly
defined position in the national administration including access to high levels of
authority within the governmental structure. The duties of the Regulatory Authority
generally include:
 Licensing or registering ionizing radiation sources, facilities and users;
 Proposing and issuing codes of practice;
 Advising on radiation protection matters;
 Keeping records of sources and personnel radiation doses;
 Carrying out inspections; and
 Emergency planning.
The powers of the inspectors of the Regulatory Authority should be well
defined and consistency of enforcement should be maintained, with provision for
appeal by those responsible for radiation sources. Directives to both inspectors and
regulated persons should be clear. Regulatory authorities may need to provide
guidance on how certain regulatory requirements are to be fulfilled for various
practices, for example in regulatory guideline documents. An attitude of openness
and cooperation should be fostered between regulated persons and inspectors,
which includes facilitating the access by inspectors to premises and to information.
The Regulatory Authority represents an important national expertise in
radiation protection and must secure and update its professional capability, for
example by international contacts with other regulatory authorities, professional
groups or individual experts.
4.
REFERENCES
1. INTERNATIONAL ATOMIC ENERGY AGENCY. International Basic Safety
Standards for Protection Against Ionizing Radiation and for the Safety of
Radiation Sources. Safety Series No.115, IAEA, Vienna (1996).
2. INTERNATIONAL ATOMIC ENERGY AGENCY, Safety of Nuclear Installations,
Safety Series No. 110, IAEA, Vienna (1993).
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RADIATION PROTECTION IN NUCLEAR MEDICINE
PART 3. PRINCIPLES OF RADIATION PROTECTION, THE INTERNATIONAL
FRAMEWORK AND REGULATORY REQUIREMENTS
3. INTERNATIONAL ATOMIC ENERGY AGENCY, Radiation Protection and the
Safety of Radiation Sources, Safety Series No. 120, IAEA, Vienna (1996).
4. INTERNATIONAL
ATOMIC
ENERGY
AGENCY.
Organization
and
Implementation of a National Regulatory Infrastructure Governing Protection
Against Radiation and the Safety of Radiation Sources. IAEA-TECDOC-1067,
IAEA, Vienna (1999).
5. INTERNATIONAL ATOMIC ENERGY AGENCY. Model Regulations on Radiation
Safety in Nuclear Medicine. (in preparation).
6. INTERNATIONAL ATOMIC ENERGY AGENCY. Safety Assessment Plans for
Authorizations and Inspection of Radiation Sources. IAEA-TECDOC-1113, IAEA,
Vienna (1999).
7. INTERNATIONAL ATOMIC ENERGY AGENCY. Draft Safety Guide on Radiation
Protection in Medical Exposure (in preparation).
8. INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION. 1990
Recommendations of the International Commission on Radiological Protection,
ICRP Publication No. 60. Oxford, Pergamon Press, 1991 (Annals of the ICRP 21,
1-3).
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