The dosimeters described are worn on the trunk within a distance of:

• A. 5 cm
• B. 15 cm
• C. 25 cm
• D. 50 cm

Answer: (B)

Placing the dosimeter where it can best represent the dose to the whole body depends on keeping a consistent radiation geometry. When worn on the trunk, about 15 cm from the body surface, the badge sits in a position that reflects the exposure to the central parts of the body and most internal organs, while still being practical to wear and not overly influenced by skin dose or clothing.

If the dosimeter were placed very close to the skin, readings would be more affected by skin dose and local variations in clothing, giving a less reliable estimate of whole-body exposure. If it were placed much farther away, the reading could be increasingly influenced by shielding and distance from the body, underestimating the dose to deep organs. The 15 cm distance balances these factors, providing a repeatable, representative measure of the dose the body would accumulate under typical working conditions.

That’s why 15 cm is the best choice for the trunk placement.