Dose equivalent, when expressed in sieverts, accounts for the type of radiation and its biological effect.

• A. True
• B. False
• C. Only absorbed dose
• D. Only exposure rate

Answer: (A)

The idea being tested is that dose equivalent, when written in sieverts, reflects both the type of radiation and how biologically damaging it is. Absorbed dose tells you how much energy is deposited in tissue, but not all radiation types cause the same harm for the same energy. To account for this, a radiation weighting factor (wR) is applied to the absorbed dose, giving dose equivalent H = D × wR. This value, measured in sieverts, conveys risk by incorporating both the amount of energy deposited and how damaging that energy is for the tissue.

For example, alpha particles have a much higher wR than photons or electrons, so the same absorbed dose results in a much larger dose equivalent with alpha radiation. Neutrons have wR values that depend on their energy, reflecting varying biological effects. In dental radiology, X-rays (photons) have wR ≈ 1, so the dose equivalent closely matches the absorbed dose, but the concept still holds—the sievert measures biological risk, not just energy deposition.

The other ideas don’t fit because simply using absorbed dose ignores biological effectiveness, and focusing on exposure rate addresses how quickly energy is delivered rather than the total biological impact.