Which is the SI unit of dose equivalent?

Which is the SI unit of dose equivalent?

• A. Sievert (Sv)
• B. Rem
• C. Gray
• D. Rad

Answer: (A)

Dose equivalent expresses how harmful radiation can be to living tissue, not just how much energy is deposited. The SI unit for this quantity is the sievert (Sv). It ties biological impact to energy deposited by including a radiation weighting factor, so the dose equivalent H equals the absorbed dose D (in grays) times this factor Q (which is dimensionless). That means 1 Gy from X-rays or gamma rays (where Q is 1) corresponds to 1 Sv. More damaging radiations, like alpha particles, have a higher Q, so the same energy deposited results in a larger dose equivalent. Gray measures energy per mass (not biological effect), and rem and rad are older or non-SI units (1 rem equals 0.01 Sv, 1 rad equals 0.01 Gy).

Dose equivalent expresses how harmful radiation can be to living tissue, not just how much energy is deposited. The SI unit for this quantity is the sievert (Sv). It ties biological impact to energy deposited by including a radiation weighting factor, so the dose equivalent H equals the absorbed dose D (in grays) times this factor Q (which is dimensionless). That means 1 Gy from X-rays or gamma rays (where Q is 1) corresponds to 1 Sv. More damaging radiations, like alpha particles, have a higher Q, so the same energy deposited results in a larger dose equivalent. Gray measures energy per mass (not biological effect), and rem and rad are older or non-SI units (1 rem equals 0.01 Sv, 1 rad equals 0.01 Gy).