Longitudinal monitoring of whole body counter NaI(Tl) detector efficiency

Assessing accuracy of radiation counting systems over time is critical. We examined long-term WBC performance in detail. Efficiency factors for 54 detectors were updated annually over several years. Newer efficiency values were compared with baseline and with annual values. Overall system efficiency has declined (−1.9% over 3 yrs) and appears to be doing so at an increasing rate. Having more specific performance data on individual components can make the process of system maintenance and repair more straightforward and efficient.