Roentgen equivalent man

The roentgen equivalent in man (or mammal) (abbreviated rem; symbol rem, or often but incorrectly R) is an older, CGS, unit of equivalent dose, effective dose, and committed dose. Quantities measured in rem are designed to represent the stochastic biological effects of ionizing radiation, primarily radiation-induced cancer. These quantities are a complex weighted average of absorbed dose, which is a clear physical quantity measured in rads. There is no universally applicable conversion constant from rad to rem; the conversion depends on relative biological effectiveness (RBE).