What is the SI unit of absorbed dose?

The SI unit of absorbed dose is the Gray (Gy). This unit quantifies the amount of radiation energy absorbed per kilogram of matter, specifically in biological tissues, and is essential in the field of radiation protection, radiology, and nuclear medicine. The definition of one Gray is equal to one joule of radiation energy absorbed per kilogram of material.

The significance of the Gray as the standard unit is that it provides a more universal measure compared to older units such as the Rad, which is still used in some contexts. The Rad has a conversion factor where 1 Gray equals 100 Rads, but the use of SI units like the Gray simplifies calculations and standardizes communication across international scientific and medical communities.

While Sievert and Rem are units that assess biological effects of radiation, they relate to dose equivalent rather than absorbed dose. The Sievert is used to measure the health effect of ionizing radiation, and the Rem is an older unit equivalent to Sieverts, which underlines the distinction between absorbed dose (Gray) and effective dose (Sievert). Therefore, the correct unit for measuring the absorbed dose specifically is the Gray.