Radiation exposure Flashcards
what are the 3 categories of radiation exposure
- occupational exposure (voluntary)
- medical exposure
- public exposure (imposed)
what is the effective dose limit for occupational exposure
20mSv/yr for radiation workers
what is the effective dose limit for public exposure
1mSv/yr
what is the dose limit for medical exposure
dose limits do not apply to medical exposures
- diagnostic reference levels recommended
what are departments expected to do in the case of medical exposure
survey their own doses, and investigations should be undertaken in XR if doses exceed their levels
what type of radiation contributes to the public most
diagnostic>therapeutic
what are deterministic effects
do not occur below a threshold dose
- severity increases above threshold dose
what is stochastic effects
- no threshold dose
- risk of damage increases as dose increases
- at low doses biological effects not predictable
- BUT always some risk
inherited radiation damage
- does not introduce new, unique mutations
- may increase the incidence of the same mutations that occur spontaneously
the aims of radiation protection
- prevent deterministic effects by keeping doses below threshold
- reduce the risk of stochastic effects to levels considered acceptable
what is absorbed dose
biological effects in any tissue are proportional to amount of energy absorbed per unit mass of tissue
what is equivalent dose (Ht)
different relations have different biological effectiveness for same amount of energy absorbed
what is effective dose
- different organs of body are assigned tissue weighting factors (WT)
- to reflect the different sensitivity of each organ to radiation damage
what is DRL
diagnostic reference levels
how often are DRLs reviewed
reviewed at 5-year intervals
