What is the general approach to estimating dose from inhalation or ingestion intake?

• A. Use only air concentration to estimate a dose, without biokinetic models.
• B. Guess based on historical data and assume a standard dose.
• C. Determine intake, apply biokinetic models for distribution/retention, and multiply by dose coefficients to obtain committed effective dose.
• D. Measure ambient radiation, estimate exposure time, and divide by shielding thickness.

Answer: (C)

Estimating dose from inhalation or ingestion starts by quantifying how much material actually entered the body (the intake). Once you know the intake, you use biokinetic models to describe how the radionuclide moves, distributes, and is retained or excreted in the body over time. Those models tell you which organs receive activity and for how long. Finally, you multiply the intake by dose coefficients, which are factors that convert activity in the body into an effective dose (committed effective dose) for that radionuclide and route. This combination—intake, biokinetic distribution/retention, and dose coefficients—provides a physically meaningful estimate of the long-term risk.

Why this approach fits: air concentration alone doesn’t tell you how much enters the body or what happens to it afterward, and guessing from historical data doesn’t account for the specific radionuclide, its chemical form, or how the body processes it. External measurements and shielding relate to external exposure, not internal dose from intake.