Determining effective dose equivalent for external photon radiation: assessing effective dose equivalent from personal dosemeter readings

Since January 1994, US nuclear plants have implemented Title of 10 Part 20 of the US Code of Federal Regulations which adopted the methodology of ICRP 26 for effective dose equivalent (HE) for internally deposited radionuclides. To provide general guidance for assessing HE from external photon exposures, a two-phase research programme was performed. This article presents the results for the second phase - assessment of HE using personal dosemeters. By using a Monte Carlo photon transport code, personal dosimetry was simulated at 480 different locations on the surface of a hermaphroditic phantom. The dosemeter readings were compared with HE calculated for a variety of photon sources completed during the first phase of this study. The data suggest that the current one-badge approach is still valid in assessing HE for routine exposure in many radiation fields and two dosemeters may be used for situations in which the exposure is less uniform. Algorithms to relate dosemeter readings to HE are discussed for uniform and non-uniform exposures. (author)