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内容記述 |
Over the past 100 years, the International Commission on Radiation Units and Measurements (ICRU) has provided scientific insight and guidance to the radiation protection community. As with any scientific endeavor, the development, enhancement, recommendations, and guidance evolve as the understanding of the underlying principles and physics improves. Throughout this evolution, the ICRU has consistently updated its recommendations to the radiation protection community through various reports. Central to radiation protection is the measurement, with instruments and personal dosimeters, of radiation fields. These measurements may be of fundamental physical quantities such as the number and energy of radiation particles that traverse a region or of subsequent effects of this radiation field such as ionization produced in air or absorbed dose delivered to a specific region. The recommendations of the ICRU have evolved and adapted in accordance with the increased understanding of fundamental physical processes and the effects of exposure to radiation to meet the challenges faced by radiation protection professionals. Practical radiation protection relies on the measurement of operational quantities to guide the process of optimization of exposure and to demonstrate that dose limits and constraints have been respected. This is the field of radiation protection dosimetry, and the measuring instruments are dosimeters and monitors, the latter used for the measurement of dose rates.The present report aims to provide an overview of the currently available techniques for radiation protection dosimetry of external exposure. It bridges the gap between textbooks of radiation protection or detector technologies and the current state of the science as reported in reviewed publications and technical manuals of manufacturers. It may also serve as an introduction to newcomers in radiation protection, giving them an overview of the wide spectrum of applications, techniques, and instruments in external radiation protection.After an introduction to protection and operational quantities in radiation protection, notably personal and ambient dose equivalent as defined in ICRU Report 51 (Allisy et al., 1993) and personal and ambient dose defined in ICRU Report 95 (Bartlett et al., 2020), two sections focus on external dosimetry of photons, electrons and neutrons. In these sections, the impact of the operational quantities introduced in ICRU Report 95 on dosimeters and instruments are shown and discussed. These are followed by a section on dosimetry techniques for specific situations which are outside the normal operating range of the dosimeters described in the previous sections. This encompasses situations where no single radiation type dominates the overall exposure, where the energy of radiation is very high, or where the time structure of the radiation is pulsed. The section on accident dosimetry covers very high doses and dose rates. Today, computer simulation plays a cardinal role in radiation protection dosimetry: conversion coefficients of the operational quantities for the calibration of dosimeters are calculated by Monte Carlo simulation and new dosimeter types are designed virtually on the computer before the construction of prototypes. A full section is dedicated to this development. Finally, type testing and calibration of dosimeters and monitors are described in detail. Two appendices describe evaluation algorithms for dosimeters and reporting and recordkeeping of the results of dosimetry. |
