Analysis of the relationship between operational quantity used for area monitoring and protection quantity for external exposure

Endo, Akira   

This report presents a comprehensive analysis of the relationship between three quantities used for area monitoring - ambient dose equivalent , maximum dose equivalent , and ambient dose - and effective dose for external irradiation by photons, neutrons, electrons, positrons, protons, muons, pions, and helium ions. For the analysis, calculations were performed using PHITS (Particle and Heavy Ion Transport code System) and the ICRU sphere. The analysis result shows that and can induce large differences in the estimation of effective dose over a wide energy range for various particle types covered by ICRP Publication 116 while can conservatively estimate effective dose within the acceptable range for area monitoring. In other words, and have limitations in estimating effective dose, and using is recommended as a more appropriate quantity for the purpose. This conclusion supports the proposal of ICRU Report 95 to use for estimating effective dose in various external exposure situations. The use of ambient dose is particularly important in situations where various types of radiation are encountered, such as the use of radiation in the medical and academic fields and exposure in aviation and can meet the evolving requirements of radiation monitoring for the expansion of the field of radiological protection.