Introduction to nuclear medicine technology NMT 231 Aya Ahmed Saeed

Radiation Protection

Radiation is a Tool Radiation has many wonderful uses Diagnose disease Cure cancer Analytical tools for industry and medicine Sterilize medical equipment and food, etc Like anything, it can be misused, and Like anything, too much is not good for you L4

Is there a safe point? If not, how to deal with the problem? Ionizing Radiation We live with 1-3 (10) mSv/y (Back ground) Can kill 4000 mSv Is there a safe point? If not, how to deal with the problem? L4 21L2

Objectives of Radiation Protection PREVENT occurrence of deterministic effects Cataracts Skin burns Transient hematopoietic Necrosis etc, MINIMIZE the probability of stochastic effects cancer genetic L4

Systems of Protection Achieving objectives requires: Source-related rules: how to maximize benefits from use of technology while maintaining individual related rules (minimum time, use maximum distance and shielding) Individual-related rules: dose limit for maximum safety Based upon 3 principles: Justification: Benefit of a practice must offset (outweigh, be more than) the radiation detriment Optimization: Exposures and likelihood of exposure should be ALARA kept as low as reasonably achievable, (economic and social factors being taken into account) Limitation: limits for protection of workers and public. These Principles apply when dealing with all potentially harmful substances or technologies (chemicals, traffic, sports etc.), requiring: Clear benefit 2. lowest possible risk 3. tolerable limits تبرير الإستخدام الإستخدام الأمثل وضع حدود L4

Principles of Radiation Protection SYSTEM Justification Benefit>risk Optimization ALARA Limitation/constraints Numerical dose limits Principle 1 Principle 2 Principle 3 Order of application of principles L4

Principles of Radiation Protection Justification In medicine, we must not give a person a radiation exposure unless there is good reason, and the person will benefit from the procedure For workers, the public and for patients, any unnecessary exposure must be avoided

Principles of Radiation Protection Limitation the ICRP specify dose limits which must not be exceeded Dose limits are NOT a permitted limit Dose limits are designed to avoid deterministic effects, and to limit the occurrence of stochastic effects to acceptable levels

Principles of Radiation Protection Optimizations as well as ALARA (As Low As Reasonably Achievable), dose limits may be reduced by using additional constraints where justified.

Radiation Protection Can Be Simple

Basic Safety Precautions (1) Time - more time near source means more dose Shielding -appropriate use of shielding materials Distance - inverse square law

Basic Safety Precautions (2) Inverse square law radiation from a point source decreases by the square of the distance Dose is proportional to 1/(distance)2 ie. twice the distance gives 1/4 the dose, but half the distance gives 4 times the dose

Basic Safety Precautions (3) Shielding : Use of high atomic number and high density materials eg. lead, concrete, steel Normal building materials eg. brick, mortar, wallboard, can be either very poor shielding materials, or have very variable and unpredictable properties

Shield Position and Size Always work behind shields (shield material and thickness depends on type of radiation emitted and quantity being handled) Shield source: you protect everybody Shield person: you protect one body L4

Guidelines Recording Levels: levels at which values received should be entered in worker records. الحد الأدنى لتعرض العامل الواجبة التسجيل Investigation levels: values above which investigation is to be conducted. حد تعرض العامل يجب بعدها إجراء تحقيق لمعرفة الأسباب Action level: dose rate or activity concentration above which remedial actions are necessary حد الجرعة أو التلوث الذى يستوجب إتخاذ إجراءات تصحيحية Reference Levels of Medical Exposure: Exposure of patients above this level is assumed to result in an unnecessarily excessive dose for the purpose,يعتبر تعرض المريض فوق هذا المستوى تعرضاً غير مبرر Intervention levels IL: levels at which intervention and counter measures should be carried out. (IL is also known as Protective Action Guides PAG or Emergency Reference Levels ERL) مستوى تعرض يستوجب التدخل وإتخاذ إجرآت على وجه السرعة Cost Benefit Analysis: an optimization procedure setting exposures where efforts for further reduction cannot be justified. L4

Controlled Area: Supervised area: An area where it is necessary to follow special procedures to restrict exposure to ionizing radiation, or An area where any person is likely to receive 3/10th of the dose limit or more Supervised area: Any area where it is necessary to keep conditions under review, or An area where it is possible for a person to receive a dose > 1 mSv/y or 1/10th the dose limit. L4

Local Rules Anyone entering a controlled area must either be a classified worker, or a patient who have read and/or understood the local rules Usually, new employees must read and sign to say they have read the local rules before they are allowed to enter a controlled area. They must learn how to: Protect patients Protect yourself Protect other workers Protect the environment Requirement of Monitoring L4

CONTAMINATION Part 5. Occupational Protection

Contamination of the worker Part 5. Occupational protection Radiation protection in nuclear medicine Contamination of the worker Spills Improper administration Experimental work with animals Emergency surgery of a therapy patient Autopsy of a therapy patient Part 5. Occupational Protection

Part 5. Occupational protection Radiation protection in nuclear medicine To minimize contamination risks - adopt clean operating conditions - adopt good laboratory practices - do not eat, smoke etc… - use protective gloves and clothing Part 5. Occupational Protection

Part 5. Occupational protection Radiation protection in nuclear medicine PROTECTIVE CLOTHING The image to the right is an example of clothing if the preparation of radiopharmaceuticals have to be done in a sterile environment Appropriate clothing should as a minimum include lab coat and gloves.National regulations may require more. Part 5. Occupational Protection

DECONTAMINATION PROCEDURES Part 5. Occupational protection Radiation protection in nuclear medicine DECONTAMINATION PROCEDURES Use adsorbent paper on wet spill or wet absorbent paper on dry spill Repetitively swab the area inwards towards the center of the spill Place contaminated paper in a plastic bag or container Monitor the area Repeat the procedure until the exposure rate is below given limits If the decontamination is not successful, mark the contaminated area and classify the room as a controlled area If not already done) until the contamination is completely removed. Part 5. Occupational Protection

Decontamination of skin Part 5. Occupational protection Radiation protection in nuclear medicine Decontamination of skin If contamination of the skin occurs, immediately the area should be thoroughly washed using mild soap and tepid (not hot) water. Particular care should be paid to cleaning under the fingernails. If this does not bring the contamination to an acceptably low level the procedure should be repeated using a decontaminating detergent. Scrub with a nail brush but take care not to break the skin. Part 5. Occupational Protection

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