Which three variables must be known to calculate the effective dose (EfD) for a patient or occupational worker?

Which three variables must be known to calculate the effective dose (EfD) for a patient or occupational worker?

• A. absorbed dose, dose rate, exposed tissue types
• B. absorbed dose, exposed tissue types, radiation type
• C. dose rate, distance from source, radiation type
• D. exposure, tissue location, shielding factor

Answer: (B)

Effective dose reflects both how much energy is deposited in specific tissues and how sensitive those tissues are, as well as how harmful the radiation type is. In practice, you compute this by first finding the absorbed dose in each irradiated tissue (D_T), then applying a tissue weighting factor (w_T) to account for each tissue’s sensitivity, and a radiation weighting factor (w_R) to account for the radiation type’s relative biologic effectiveness. The formula shows E = Σ_T w_T H_T with H_T = w_R D_T, so you need three pieces of information: the absorbed dose to the tissues, which tissues are exposed (to apply the correct tissue weights), and the type of radiation (to apply the correct radiation weight). The other factors like dose rate, distance from the source, or shielding do not enter the standard EfD calculation directly; they influence how much dose is delivered but aren’t part of the EfD computation itself.

Effective dose reflects both how much energy is deposited in specific tissues and how sensitive those tissues are, as well as how harmful the radiation type is. In practice, you compute this by first finding the absorbed dose in each irradiated tissue (D_T), then applying a tissue weighting factor (w_T) to account for each tissue’s sensitivity, and a radiation weighting factor (w_R) to account for the radiation type’s relative biologic effectiveness. The formula shows E = Σ_T w_T H_T with H_T = w_R D_T, so you need three pieces of information: the absorbed dose to the tissues, which tissues are exposed (to apply the correct tissue weights), and the type of radiation (to apply the correct radiation weight). The other factors like dose rate, distance from the source, or shielding do not enter the standard EfD calculation directly; they influence how much dose is delivered but aren’t part of the EfD computation itself.