Determining the amount of RM in the body is accomplished by which methods?

• A. Whole body counters
• B. Bioassays
• C. Both whole body counters and bioassays
• D. None

Answer: (C)

Assessing how much radioactive material is inside the body relies on two complementary approaches: whole body counting and bioassay. A whole body counter directly detects the radiation emitted by radionuclides present in the body, giving a direct measurement of the body burden for radionuclides detectable by the detector. Bioassay analyzes biological samples such as urine or feces (and sometimes blood) to estimate intake and retention, which can be used to back-calculate the amount present in the body over time, especially for radionuclides that are difficult to detect in vivo or are excreted readily. Because different radionuclides have different detection challenges—some are best seen with in vivo gamma detectors, others are better quantified through excreta measurements—using both methods provides a complete and accurate assessment of internal contamination.