introduction to radiation protection

deterministic effects

known as “tissue reactions”

occur at high doses of radiation exposure

known threshold must be exceeded for the effects to be seen

severity increases with dose

repair and recovery can occur

stochastic effects

governed by laws of chance

can occur even at low doses

are not associated with a threshold

probability of occurrence is related to dose, more likely to occur as dose increases

severity is not related to dose

examples of deterministic effects

lens opacities

skin injuries (e.g. burns)

epilation (hair loss)

blood count changes

examples of stochastic effects

cancer

genetic defects

aim of radiation protection

in applying the system of radiological protection, the objective is to ensure that deterministic effects are avoided and probability of stochastic effects occurring is extremely low

role of united nations scientific committee for the effects of the atomic radiation (UNSCEAR)

studies the effects of atomic radiation

provides reports to UN general assembly about use and effects of ionizing radiation

role of: international commission of radiological protection (ICRP)

provides recommendation to regulatory bodies and agencies relating to radiation protection

no regulatory role or power

international atomic energy agency (IAEA)

independent intergovernmental, science and technology-based organization within the UN

establishes standards of safety and provides support for the application of the standard

principles of radiation protection

• justification
  any decision that alters (i.e. introduce, reduce, or remove) the radiation exposure situation should do more good than harm

• optimization
  doses should all be kept as low as reasonably achievable, taking into account economic and societal factors

• dose limitation
  the total dose to any individual should not exceed the relevant limits

types of exposure situations

planned

emergency

existing

categories of exposure

occupational

public

medical

dose limits

effective dose (wholebody): occupational (20mSv) public (1mSv)

equivalent dose (lens of the eye): occupational (20mSv) public (15mSv)

equivalent dose (skin): occupational (500mSv) public (50mSv)

equivalent dose (hands & feet): occupational (500mSv)