Which method determines the amount and type of radioactivity in the body?

Which method determines the amount and type of radioactivity in the body?

• A. Bioassays— analyzing samples of fecal material/ urine
• B. Whole body counters— amount/type of radioactivity (gamma)
• C. Air sampling
• D. Skin swabs

Answer: (B)

To know how much radioactivity is inside the body and which radionuclides are present, you use a whole body counter. It detects gamma rays emitted by radioactive material distributed throughout the body and converts those signals into a direct measure of internal activity. The energy of the detected gamma photons acts like a fingerprint, allowing you to identify the specific isotopes and quantify how much of each is present. This direct internal measurement is the key advantage over other methods. Bioassays analyze excreted material like urine or feces to estimate intake, but they’re indirect and rely on excretion patterns. Air sampling and skin swabs assess environmental or surface contamination, not what’s inside the body.

To know how much radioactivity is inside the body and which radionuclides are present, you use a whole body counter. It detects gamma rays emitted by radioactive material distributed throughout the body and converts those signals into a direct measure of internal activity. The energy of the detected gamma photons acts like a fingerprint, allowing you to identify the specific isotopes and quantify how much of each is present. This direct internal measurement is the key advantage over other methods. Bioassays analyze excreted material like urine or feces to estimate intake, but they’re indirect and rely on excretion patterns. Air sampling and skin swabs assess environmental or surface contamination, not what’s inside the body.