In terms of radiation dose, which unit expresses a dose of radiation absorbed by tissue?

The unit that expresses the dose of radiation absorbed by tissue is the rad. This term specifically quantifies the amount of energy deposited by ionizing radiation in a specified mass of tissue. One rad corresponds to an absorbed dose of 0.01 joules of radiation energy absorbed per kilogram of tissue.

The understanding of radiation dose measurement is crucial in radiography, as it relates to the potential biological effects of radiation exposure on human tissue. The rad helps to understand how much radiation a body has absorbed, which is essential for assessing risks and implementing safety measures.

Other units mentioned, such as rem, roentgen, and gray, serve different purposes, but they do not represent absorbed dose by tissue in the same way the rad does. The rem is actually a measure that accounts for the biological effect of the absorbed dose (adjusted for the type of radiation), while the gray is the SI unit equivalent to the rad, with one gray being equal to 100 rads. The roentgen, on the other hand, measures exposure in air rather than absorbed dose in tissue. Thus, the rad effectively communicates the specific dosimetric quantity of radiation received by tissues.