Dose Limits for Exposure to Ionizing Radiation Sherer

Effective Dose Limiting System The idea that exposure to radiation can/may induce cancer. The result is that radiation protection guidelines are based on the possibility of getting cancer not some other effect.

Radiation Safety Program All facilities must have a radiation protection/safety program in place. Radiation Safety Committee Radiation safety Officer (RSO)

Effective Dose Limiting System Looks to establish the upper limit of exposure to ionizing radiation resulting in a negligible risk of injury or genetic defect. Can be whole body, partial body (extremity, eye) and individual organs. Non-stochastic (deterministic) and stochastic (probabilistic) Occupational limits are based on comparing outcomes against other occupational hazards.

Radiation Induced Responses Non-stochastic Deterministic Directly related to the dose received, threshold Early Erythemia Decreased blood count Epilation Acute Radiation Syndromes (ARS) Late Cataracts Fibrosis Sterility Organ atrophy

Stochastic Probabilistic Mutational, non-threshold, randomly occurring, all or nothing The greater the dose the greater the chance of the effect occurring. NOT is it going to occur. Cancer and genetic effects

Basis for Effective Dose Limiting System While we have already discussed the fact different forms have radiation have different effects (equivalent dose) some tissues are more sensitive than others. Tissue weighting factor allows overall risk to be determined.

Occupational MPD 50 mSv or 5 rem annually Pregnant 0.5 mSv per month 5 mSv for the entire pregnancy

Public MPD 1 mSv or 0.1 rem or 100 mrem Educational exposure 1 mSv or 0.1 rem annually Notice it is the same as the general public

Radiation Hormesis The potential that small radiation exposure is actually beneficial.