Dose equivalent H_T is equal to absorbed dose multiplied by which factor?

• A. The energy per unit mass
• B. The tissue weighting factor w_R
• C. The radiation dose rate
• D. The exposure time

Answer: (B)

Biological damage depends on radiation quality, not just energy deposited. To capture this, the dose equivalent to a tissue is found by multiplying the absorbed dose D_T (in Gy) by the radiation weighting factor w_R. The factor w_R is dimensionless and represents how damaging a given type of radiation is per unit energy deposited. That’s why the result is expressed in sieverts (Sv): Gy × w_R yields Sv when w_R is 1 for low-LET radiations like X-rays or gamma rays, and higher values (for example, around 20 for alpha radiation) reflect greater biological impact. So, the correct multiplier is the radiation weighting factor, w_R.