Gray (unit)

Gray (unit)

The Gray (SI unit of radiation dose absorbed by matter) is a derived unit of ionizing radiation dose in the International System of Units (SI). It is defined as the absorption of one joule of radiation energy per kilogram of matter. It is named after British physicist Louis Harold Gray, who is known for his work on the effects of radiation on the human body. The unit is represented by the symbol Gy.

Definition and Use

The gray is an SI unit for the measure of absorbed radiation dose. It is used in the field of radiology, radiation therapy, and radiation protection, and is primarily used to measure the absorbed dose in the patient's tissue during radiotherapy.

One gray is equivalent to one joule of energy deposited in a kilogram of a substance. The higher the number of grays, the higher the absorbed dose of radiation, and thus the higher the potential damage to the tissue.

Measurement and Dosimetry

The measurement of absorbed dose profiles in a medium is known as dosimetry. In radiation therapy, dosimetry is used to calculate the correct dose of radiation. The gray is used in calculations to ensure that the target area receives the correct dose, while minimizing the dose to surrounding healthy tissue.

Effects on Human Health

The effects of exposure to large amounts of radiation can be severe, including radiation sickness, cancer, and death. The risk of health effects from radiation is dependent on the type of radiation, the duration of exposure, and the part of the body exposed.

See Also

• Sievert
• Radiation therapy
• Radiation protection
• Radiation sickness
• Cancer