What is the average accuracy of a film badge?

• A. +- 1%
• B. +- 9%
• C. +- 25%
• D. +- 40%

Answer: (C)

Film badges measure exposure by the darkness of developed photographic film, but the film’s response varies with radiation energy, beam quality, angle of incidence, and how the film is processed. That variability introduces noticeable uncertainty in the dose readouts. The typical, practical accuracy you’re taught for film badges is about plus or minus 25 percent, meaning the reported dose can differ from the true dose by roughly a quarter. This level of imprecision is why film badges are considered less precise than newer dosimeters like thermoluminescent dosimeters or optically stimulated luminescent dosimeters, which generally have tighter uncertainties. Options suggesting much tighter precision (like ±1% or ±9%) aren’t consistent with the known performance of film badges, and a much larger tolerance (like ±40%) exceeds the usual range encountered in standard practice.