IAEAInternational Atomic Energy Agency

Regulations

Part III: Radiation Protection Performance Requirements

Day 8 – Lecture 5(3)

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To provide an understanding of the basic concepts of justification, optimization and dose limitation.

Objectives

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• Justification of Practices• Dose Limitation• Optimization of Protection and Safety

.

Content

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General principles

• Benefit to the exposed individuals or the society shall offset the radiation harm, taking into account social, economic and other relevant factors.

Justification of Practices

• Applicant for authorization provides sufficient evidence of the benefits versus harm.

• Justification is considered in the authorization process.

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Practical application• Overall assessment of justification is made when new

types of practices are proposed.

Justification of Practices (cont)

• For individual cases, assessment is required that the practice is or will be conducted in a manner typical for existing types of practices that are already generally considered justified.

• The Regulatory Body should review the justification of existing types of practices whenever new important evidence on their efficacy or harm is acquired.

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Practices deemed unjustified include: • the deliberate addition of radioactive substances in, or

activation of: food, feed, beverages, cosmetics (intake by, or

application to, a human being); toys, personal jewellery, adornments (frivolous

use of radioactive substances); human imaging using radiation used as a form of

art or for publicity purposes;

Justification of Practices (cont)

• any other practice determined by the Regulatory Body to be unjustified.

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Dose limits• Occupational dose limits:

workers; apprentices and students of 16-18 years of age; specially authorized exposures.

• Dose limits for the public

Dose Limitation

Dose limits are not applicable to medical exposures

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Workers• Effective dose • 20 millisieverts per year averaged over 5 years; • 50 millisieverts in any single year.

Dose Limits

Equivalent dose• to the lens of the eye; 20 millisieverts per year

averaged over 5 years;• extremities (hands and feet) and the skin; 500

millisieverts per year.

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Effective dose

• 6 millisieverts per year.

Dose Limits (cont)

Equivalent dose • to the lens of the eye 20 millisieverts per year; • extremities (hands and feet) and the skin: 150

millisieverts per year.

Apprentices and students 16-18 years of age

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Dose Limits (cont)

Apprentices and students 16-18 years of age (cont)

• No person under the age of 16 years shall be subjected to occupational exposure.

• No person under the age of 18 years shall be allowed to work in a controlled area unless supervised and then only for the purpose of training.

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Equivalent dose• to the lens of the eye; 15 millisieverts per year.• extremities (hands and feet) or the skin; 50 millisieverts

per year.

Dose Limits (cont)

Members of the public

Effective dose• 1 millisievert per year.• in special circumstances, a higher value of effective dose in a

single year provided 1 millisievert per year over 5 years is not exceeded.

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• Case by case approval of the Regulatory Body;• Requirements:

– radiation safety is optimized– workers involved have been consulted

Specially authorized exposures

• Temporary change in some dose limit:– for a limited period of time– relates to specified work areas

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For exposures from any source within a practice

• the magnitude of individual doses,

• the number of people exposed, and

• the likelihood of incurring exposures;

• shall be kept as low as reasonably achievable (ALARA).

Optimization of Protection and Safety

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Dose constraints

• are used in the context of optimisation within a practice;

Optimization of Protection and Safety (cont)

• are established by the Regulatory Body;

• are less than dose limits;

• are not applicable to medical exposures;

• for public exposures, are a tool for considering contributions from different practices and sources.

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Reference Levels:

• represent the level of dose above which it is judged to be inappropriate to allow exposures to occur;

Optimization of Protection and Safety (cont)

• used for optimization in emergency and existing exposure situations.

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• Diagnostic reference levels;

• Dose constraints for exposures of carers and comforters and of volunteers program biomedical research;

• Criteria and guidelines for the release of patients under therapeutic procedures.

Optimization of Protection and Safety (cont)