Gray (unit)

SI derived unit of absorbed dose of ionizing radiation

The gray (symbol: Gy) is the unit of ionizing radiation dose in the International System of Units (SI), defined as the absorption of one joule of radiation energy per kilogram of matter. It is used as a unit of the radiation quantity absorbed dose that measures the energy deposited by ionizing radiation in a unit mass of absorbing material, and is used for measuring the delivered dose in radiotherapy, food irradiation and radiation sterilization. It is important in predicting likely acute health effects, such as acute radiation syndrome, and is used to calculate equivalent dose using the sievert, which is a measure of the stochastic (probable) health effect on the human body.

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