Dose equivalent units include which of the following?

• A. Rem
• B. Rad
• C. Gray
• D. Coulomb/kg

Answer: (A)

Dose equivalent is a measure of the potential biological harm from radiation, not just how much energy is deposited. The unit rem is used for dose equivalent because it reflects radiosensitivity by applying a weighting factor for different radiation types, linking the quantity to risk. In modern practice the sievert serves the same purpose as the SI equivalent. Absorbed dose units like rad or gray quantify energy deposited per mass, but they don’t convey biological effect. Coulomb/kg describes exposure in air, which is not the same as dose equivalent. So rem is the appropriate unit for expressing dose equivalent.