Where should a personnel dosimeter be worn on the body?

• A. at the waist over a protective apron
• B. at the collar over a protective apron
• C. at the collar under a protective apron
• D. at the waist under a protective apron

Answer: (B)

The main idea is to measure exposure to the parts of the body that are not shielded by the lead apron. The collar location, worn on top of the apron, captures radiation reaching the head and neck—areas that are not protected by the apron. This provides a meaningful estimate of exposure to the thyroid and other sensitive tissues in that region. If the dosimeter were worn under the apron, it would be shielded by the apron and would underestimate the dose to head and neck. A waist position, whether over or under the apron, does not reflect neck exposure as well, since the neck is the most vulnerable area not protected by the apron. So placing the dosimeter at the collar outside the apron gives the best measure of occupational exposure to unshielded tissues.