Which unit is traditionally used for absorbed dose equivalent?

The absorbed dose equivalent is traditionally measured in the unit known as rem (roentgen equivalent man). This unit takes into account not only the absorbed dose of radiation but also the biological effect of that radiation on human tissue. The rem is used to quantify the risk of exposure to different types of ionizing radiation, factoring in the quality of radiation — which can cause varying levels of biological damage.

In contrast, the rad (radiation absorbed dose) is merely a measure of the absorbed energy without consideration of the biological effects, making it suitable for measuring the absorbed dose in a material but not the equivalent dose that accounts for potential health risks. Roentgen is a unit specifically used for measuring exposure to X-rays and gamma rays in the air rather than for absorbed dose or dose equivalent. RBE (Relative Biological Effectiveness) is a factor used to compare the biological effectiveness of different types of radiation, but it is not a unit of measurement for absorbed dose equivalent itself.

Thus, rem is the appropriate unit to assess the biological impact of radiation exposure in terms of dose equivalent.