Which quantity represents the energy deposited per kilogram of tissue by ionizing radiation?

Which quantity represents the energy deposited per kilogram of tissue by ionizing radiation?

• A. Coulombs per kilogram (c/kg)
• B. Becquerel (Bq)
• C. Sievert (Sv)
• D. Gray (Gy)

Answer: (D)

The quantity in question is the energy deposited per kilogram of tissue, which is the absorbed dose. It directly tells you how much energy radiation has imparted to each kilogram of matter. The unit for this is the gray, defined as one joule of energy absorbed per kilogram of tissue. So, the gray is the correct choice because it specifically measures energy per mass. The other units don’t describe energy deposited per kilogram: coulombs per kilogram measures exposure in air (ionization per unit mass of air), not energy absorbed by tissue; the becquerel is a rate of radioactive decays per second, not energy deposition; and the sievert reflects biological effect by incorporating radiation type and tissue weighting factors, not the pure energy deposited per mass.

The quantity in question is the energy deposited per kilogram of tissue, which is the absorbed dose. It directly tells you how much energy radiation has imparted to each kilogram of matter. The unit for this is the gray, defined as one joule of energy absorbed per kilogram of tissue. So, the gray is the correct choice because it specifically measures energy per mass.

The other units don’t describe energy deposited per kilogram: coulombs per kilogram measures exposure in air (ionization per unit mass of air), not energy absorbed by tissue; the becquerel is a rate of radioactive decays per second, not energy deposition; and the sievert reflects biological effect by incorporating radiation type and tissue weighting factors, not the pure energy deposited per mass.