REM is equal to RAD times _____________?

• A. Quality Factor
• B. Dose Equivalent
• C. LET
• D. Exposure

Answer: (A)

The main idea is that the biologically effective dose is found by adjusting the physical dose with a factor that reflects how damaging the radiation type is. The rem is defined as the absorbed dose in rad multiplied by a Quality Factor that accounts for the varying biological effects of different radiations. So, rem = rad × Quality Factor.

Quality Factor is the multiplier chosen for the radiation type based on its LET and other biological considerations. For X-rays and gamma rays it’s 1, for alpha particles it’s much higher (reflecting greater biological damage per unit energy deposited). LET describes how densely energy is deposited along a track and influences what Quality Factor is assigned, but LET itself isn’t the multiplier in this equation. Exposure is an earlier measure of ionization in air and isn’t used to compute rem directly. Dose Equivalent is the resulting quantity (in rem or sievert), not the multiplier.