Exposure is measured in which unit in the described radiation protection framework?

Exposure is measured in which unit in the described radiation protection framework?

• A. Roentgen/ Gy_A
• B. Coulomb per kilogram
• C. Gray/ Gy_T
• D. Sievert/ Sv

Answer: (A)

Exposure refers to the amount of ionization that radiation causes in air, not the energy deposited in tissue. Historically, this quantity was measured in Roentgen, a unit defined by the ionization produced in a kilogram of air. In modern SI practice, the corresponding measure of exposure in air is air kerma, expressed as Gray in air (Gy_A). So using Roentgen or Gy_A together makes sense: Roentgen represents the traditional unit for exposure in air, and Gy_A represents the SI expression of exposure in air. The other options describe different quantities—Coulomb per kilogram is a SI measure related to exposure but not the standard historical unit used for exposure in this framework; Gray for tissue (Gy_T) is absorbed dose in tissue, and Sievert (Sv) is the effective dose.

Exposure refers to the amount of ionization that radiation causes in air, not the energy deposited in tissue. Historically, this quantity was measured in Roentgen, a unit defined by the ionization produced in a kilogram of air. In modern SI practice, the corresponding measure of exposure in air is air kerma, expressed as Gray in air (Gy_A). So using Roentgen or Gy_A together makes sense: Roentgen represents the traditional unit for exposure in air, and Gy_A represents the SI expression of exposure in air. The other options describe different quantities—Coulomb per kilogram is a SI measure related to exposure but not the standard historical unit used for exposure in this framework; Gray for tissue (Gy_T) is absorbed dose in tissue, and Sievert (Sv) is the effective dose.