Minimal (M) readings on dosimeter reports mean?

• A. A dose below the sensitivity of the dosimeter has been received
• B. A maximum dose has been received
• C. A mean (average) dose has been received
• D. Much radiation has been received

Answer: (A)

Minimal readings indicate the dose is below the dosimeter’s ability to reliably detect it. The device has a detection limit, and when the exposure is too small to stand out from background noise, the report marks it with an M. This means there was some exposure, but it’s too small to quantify precisely, not that nothing was received. It signals a negligible level for that monitoring period. If a precise value is needed, a more sensitive dosimeter or a longer measurement might reveal a measurable dose.