What is a committed dose and how is it estimated for an intake of radionuclides?

• A. The total dose expected over time from a radionuclide taken into the body; estimated using biokinetic models and dose coefficients.
• B. The dose received instantly on intake
• C. The dose from external sources only
• D. The dose after excretion ends

Answer: (A)

Committed dose is the total radiation dose that will be delivered over time from radionuclides that have entered the body. It is estimated by combining the amount of radionuclide taken into the body (intake) with biokinetic models that describe how the radionuclide is distributed, retained, and cleared, and with dose coefficients that convert that internal activity into a radiation dose. The calculation effectively integrates the internal dose over a long time horizon (accounting for biological clearance and radioactive decay), giving the overall risk from that intake. This is why the correct description matches the idea of a total dose over time from body-entrained radionuclides, using biokinetic models and dose coefficients. The other concepts describe instantaneous intake dose, external sources, or dose after excretion ends, which do not represent the time-integrated internal exposure.