Absorbed dose (Radioactivity)

Absorbed dose is a fundamental physical quantity that measures the amount of energy deposited by ionizing radiation per unit mass of matter. Expressed in joules per kilogram, its standard SI derived unit is the gray (Gy). Before the adoption of the gray, the traditional unit was the rad, where one gray equals 100 rads. Absorbed dose is critical in radiation therapy, nuclear physics, and radiation protection to quantify radiation exposure in both biological tissue and inanimate substances.