The risk of radiation-induced stochastic effects is reduced by adherence to which dose limit?

• A. EqD limits to the skin and extremities
• B. EfD limits to the whole body
• C. D limits to the skin and extremities
• D. EqD limits to the whole body

Answer: (B)

Stochastic effects, such as cancer or genetic effects, are probabilistic and depend on the overall risk to the body rather than just a single localized exposure. The best way to reduce that risk is to limit the whole-body effective dose (EfD). EfD combines the radiation dose to all irradiated organs, weighted by how sensitive each tissue is to radiation. This means EfD provides a single value that mirrors the total probabilistic risk of radiation across the body, so keeping EfD within recommended limits directly lowers the chance of stochastic effects.

Localized limits, like those for the skin or extremities, control dose to just one part of the body and don’t reflect the cumulative risk to the whole body. Similarly, using absorbed dose or equivalent dose limits for the whole body doesn’t account for the varying sensitivities of different tissues. EfD to the whole body is the measure that aligns dose control with the goal of reducing stochastic risk.