Laboratories/facilities dealing with ionizing radiation encounter radiation field which are measured using suitable gamma radiation monitors, for area and personal monitoring. These radiation monitors are subjected to periodic calibrations to confirm that they are still fit for the purpose. In India, periodic calibration of these radiation monitors is carried out by NABL accredited calibration laboratories using source exposure devices containing radionuclide sources of ¹³⁷Cs and/or ⁶⁰Co. Calibration laboratories get the output from these source exposure devices standardized by RSSD, BARC, Mumbai. RSSD, BARC, provides a report on the measured output, in the form of air kerma rates at different distances, which is traceable to relevant national standards. The laboratory then uses the standardized radiation field in day-to-day calibration, by taking air kerma rate mostly at distance of 100 cm (fixed distance) as reference for estimating radiation fields at other distances by using inverse square law. The air kerma rate values obtained by the using inverse square law shows deviation from the measured values with an allowed deviation up to 5%. The impact of this deviation cannot be corrected thus is accounted in the form of uncertainty. This paper presents an average air kerma strength-based methodology which provides a simple and effective mechanism for estimating the conventional true value of air kerma rate at various distance which adds lower uncertainty to overall uncertainty, as compared to the method of using a fixed or reference distance (say 100 cm) based air kerma rate.

处理电离辐射的实验室/设施会遇到辐射场，使用合适的伽马辐射监测器测量辐射场，以进行区域和个人监测。这些辐射监测仪定期进行校准，以确认它们仍然适合其用途。^{在印度，这些辐射监测仪由 NABL 认可的校准实验室使用含有137} Cs 和/或⁶⁰ Co放射性核素源的源暴露设备进行定期校准。校准实验室从这些源暴露设备中获取由 RSSD、BARC、孟买标准化的输出。RSSD、BARC 以不同距离的空气比动能率的形式提供测量输出报告，该报告可追溯到相关国家标准。然后实验室使用标准化辐射场进行日常校准，主要以100厘米（固定距离）距离处的空气比释动速率作为参考，利用平方反比定律估算其他距离处的辐射场。利用平方反比定律得到的空气比释动能率值与实测值存在一定的偏差，允许偏差最大为5%。这种偏差的影响无法纠正，因此以不确定性的形式进行计算。本文提出了一种基于平均空气比动能强度的方法，该方法提供了一种简单有效的机制来估计不同距离处的空气比动能率的常规真实值，与使用固定或参考的方法相比，这增加了总体不确定性的较低不确定性基于距离（例如 100 厘米）的空气比释动率。