How should internal contamination be monitored after potential inhalation of a radionuclide?

• A. Skin swabs and visual inspection.
• B. Bioassay tests (urine/feces), in vivo counting if indicated, interpretation to estimate committed dose; monitoring continues until clearance.
• C. Whole-body counting is never used.
• D. Monitor only if symptoms appear.

Answer: (B)

Internal contamination after inhalation is best monitored by measuring how much radionuclide is present inside the body and how it is cleared over time. The standard approach is bioassay monitoring—analyzing excreted material such as urine and feces to detect the radionuclide and estimate the internal burden. If indicated, in vivo counting is used to directly measure radiation or radionuclide distribution within the body (for example, whole-body or organ-specific counting). The results are interpreted to estimate the committed dose, which is the total radiation dose expected to be delivered over time due to the internalized material, and the monitoring continues until the body has cleared the radionuclide or the activity has fallen to a safe level.

Skin swabs and visual inspection only assess external contamination and cannot reveal internal uptake. Monitoring based solely on symptoms is unreliable because symptoms may be absent or nonspecific despite internal contamination. While whole-body counting is a valuable tool, saying it is never used is incorrect; it is often an important component of the assessment, used alongside bioassay and targeted in vivo measurements as needed.