Radiation Effects & Radiation Safety

ALARA principle

a principle that states that all radiation exposure to humans should be limited to levels that are as low as reasonably achievable.

coulombs per kilogram (C/kg)

the SI unit for measuring the amount of ionization in air.

deterministic

describes biologic radiation effects that are predictable; their intensity is dose dependent. These effects occur only after a certain threshold amount of exposure has been received; formerly called nonstochastic effects.

dosimeter

an instrument to detect and measure radiation exposure; a badge worn to measure cumulative occupational exposure.

equivalent dose (EqD)

a measurement of the effective dose of radiation as compared to that of 250 keV x-rays; obtained by multiplying the dose in rad or gray times the weighting factor (WR) of the specific type of radiation involved in the exposure and expressed in units of rem (British system) and sieverts (SI system)

erythema

redness, or inflammation of the skin or mucous membranes caused by the dilation and congestion of superficial capillaries; in radiography, "radiation burn" as a result of radiation treatment.

gray (Gy)

SI unit for absorbed dose. The unit is Joules per kilogram (J/kg) and is a measure of the energy imparted to matter by ionizing radiation.

roentgen (R)

the standard unit of radiation intensity in the British system of radiation measurement. It is a measurement of the intensity of radiation exposure in air. The roentgen is equal to the quantity of radiation that will produce 2.08 × 109 ion pairs in a cubic centimeter of dry air.

sievert (Sv)

the dose-equivalent unit in the SI system that results when the dose in Gy is multiplied by a weighting factor of radiation.

stochastic

describes biologic radiation effects that are random and unpredictable. Their likelihood is dose dependent, but not their severity. There is no threshold amount of exposure necessary to produce these effects.