Presentation on theme: "RADIATION PROTECTION PRINCIPLES. Prevent the occurrence of the non-stochastic effect by restricting doses to individuals below the relevant thresholds."— Presentation transcript:
RADIATION PROTECTION PRINCIPLES
Prevent the occurrence of the non-stochastic effect by restricting doses to individuals below the relevant thresholds. Reduce induction of stochastic effect Objectives of Radiation Protection
Justification of Practice Optimization of Protection and Safety Recommendations (Dose Limit ) Principles used in Radiation Protection Systems
Justification of Practice No exposure is permissible unless there is benefit associated with exposure Benefit may be to the exposed individuals or to society.
Optimization of Protection and Safety Based on the principles of ALARA (As Low As Reasonably Achievable). For any given radiation source within a practice, the magnitude of doses, the number of people exposed should be kept to as low as reasonably achievable.
DoseLimit Dose Limit Used to apply controls on each individual’s accumulation of dose. Dose limits do not include medical exposures and natural background radiation. Annual Dose Limits (ADL) There are different dose limits for : radiation workers female pregnant workers members of the public
ADL for Occupational Exposure Whole body 5 rem Eye 15 rem Pregnant Worker (9 months) 0.5 rem ADL For Exposure of Members of Public General Public: 0.1 rem Minor (18 years): 0.1 rem
ALARA ALWAYS KEEP RADIATION EXPOSURES AS LOW AS REASONABLY ACHIEVABLE Can you think of ways to do this?
TIME The exposure is to be kept as short as possible because the exposure is directly proportional to time.
TIME Dose = Dose rate x Time of exposure Example A researcher stands in an area where a survey meter reads 50 mrem/hr for a period of six hours. What is their total exposure as a result? 50 mrem/hr X 6 hr = 300 mrem
DISTANCE Distance from the radiation source should be kept as great as possible Physical Law: –Inverse Square Law DISTANCE
Doubling distance from a point source of radiation decreases dose rate to one quarter of what it was. The Inverse Square Law is: D1 X r1 2 = D2 X r2 2 Example: The dose rate one feet away from a point source is 100 mrem/hr. What is the dose rate after stepping back to a distance of two feet? D2 = (100 mrem/hr) X (1 ft) 2 /(2 ft) 2 = 25 mrem/hr
Shielding Shielding takes into consideration : –density and thickness of shielding materials, –type of radiation types of radiation and shielding required
Radiation protection principles are related to: Source Work environment Worker
Substitution Isolation –Time –Place Shielding Removal at source Source
Good housekeeping Regular monitoring Maximum allowable dose Work environment
Pre-employment examination Periodic medical examination Personal protective equipments Laboratory coat Overall or boiler suit Rubber gloves Overshoes Rubber boots Breathing apparatus Worker