What is meant by committed dose in the context of internal contamination monitoring?

• A. The long-term radiation dose expected to be received by the body from radionuclide uptake, based on intake and biological half-life.
• B. The dose delivered instantly during exposure.
• C. The dose to the skin only.
• D. The dose from ambient background radiation.

Answer: (A)

Inside the body, radionuclides deliver dose over time as they are retained and decay. The committed dose is that total dose the body will receive from that intake, calculated by integrating the dose rate over the period of retention. It depends on how much was taken in (intake) and how quickly the substance is removed from the body (biological half-life), using biokinetic models and dose-per-unit-intake factors. Because radionuclides can linger for years, the committed dose represents a long-term expectation, often expressed as committed effective dose to reflect the overall risk. This differs from an instantaneous exposure, a dose confined to the skin, or background radiation, which do not describe the long-term internal dose from uptake.