In dosimetry, a minimal (M) reading indicates what?

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

Answer: (B)

Minimal reading reflects the detector's limit of detection. When the reading is M, the dose is below the dosimeter's sensitivity, so the signal cannot be reliably distinguished from background or noise. The actual exposure could be zero or a very small value, but it lies under what the device can quantify. If a precise dose is needed, a more sensitive dosimeter or a longer exposure would be necessary. This is different from a measurable amount of radiation, which would register a value above the detection limit.