NF ISO 6980-1, M60-515-1 (11/2023)

This document specifies requirements for reference beta radiation fields produced by radioactive sources to be used for the calibration of area dosimeters, personal dosimeters and dose rate meters intended to be used for the measurement of the quantities Hp(0 .07), H'(0.07;O), Hp(3) and H'(3;O), and for the determination of their response as a function of the energy of the beta particles and the angle of impact. In beta dosimetry, the fundamental quantity is the absorbed dose rate in a tissue equivalent plate phantom. This document gives the characteristics of the radionuclides that have been used to produce reference beta radiation fields; it also gives examples of construction of suitable sources and describes methods for measuring the maximum residual beta particle energy and the dose equivalent rate at a depth of 0.07 mm in the ICRU sphere (from English International Commission on Radiation Units and Measurements). The energy range concerned is between 0.22 MeV and 3.6 MeV in maximum beta energy, or 0.07 MeV to 1.2 MeV in average beta energy, and the dose equivalent rates are between 10 µSv·h–1 and at least 10 Sv·h–1. For some sources, variations in dose equivalent rate as a function of angle of incidence are also provided. However, as ICRU report 56[5] points out, the ambient dose equivalent, H*(10), and the individual dose equivalent, Hp(10), used for area monitoring and for individual monitoring, respectively, in the case of strongly penetrating radiation are not suitable quantities for beta radiation, even for radiation capable of passing through a tissue thickness of 10 mm (Emax > 2 MeV). This document applies to two sets of reference beta radiation fields from which the radiation necessary to determine the characteristics (calibration, energy and angular dependence of the response) of an instrument can be selected. Series 1 reference radiation fields are produced by radioactive sources that are used with beam-leveling filters designed to achieve uniform dose equivalent rates over an extended area at a specified distance. The proposed 106Ru/106Rh, 90Sr/90Y, 85Kr, 204Tl and 147Pm sources produce maximum dose equivalent rates of approximately 200 mSv·h–1. Series 2 reference radiation fields are produced without the interposition of beam equalizing filters, allowing the use of planar sources with a large surface area and a range of distances between the source and the calibration plane. Near the sources only relatively small areas of uniform dose rate are produced, but this series has the advantage of extending the energy and dose rate ranges beyond those of series 1. This series series also includes radiation fields using polymethyl methacrylate (PMMA) absorbers to reduce the peak energy of beta particles. The radionuclides used are those of series 1; these sources produce dose equivalent rates of up to 10 Sv·h–1.
(Automatic translation from French)