The gray unit of absorbed dose is defined as being equal to what?

The gray (Gy) is the SI unit used to measure the absorbed dose of radiation. It quantifies the amount of energy deposited by ionizing radiation in a given mass of material, which in the context of medical imaging and radiation therapy is typically biological tissue.

The definition of a gray is specifically one joule of radiation energy absorbed per kilogram of matter. This means that when one gray of radiation is delivered, it corresponds to one joule of energy absorbed by each kilogram of the absorbing material. This relationship is important because it helps in evaluating both the biological effects of radiation and the appropriate doses needed for therapeutic procedures.

Understanding that the gray is defined in terms of energy absorbed per unit mass clarifies its significance in fields such as radiology and radiation oncology, where it applies directly to the assessment of patient exposure and treatment efficacy.