NF M60-515

ISO 6980-2:2004 specifies methods for the measurement of the directional absorbed-dose rate in a tissue-equivalent slab phantom in the ISO 6980 reference beta-particle radiation fields. The energy range of the beta-particle-emitting isotopes covered by these reference radiations is 0,066 to 3,54 MeV (maximum energy). Radiation energies outside this range are beyond the scope of this standard. While measurements in a reference geometry (depth of 0,07 mm at perpendicular incidence in a tissue-equivalent slab phantom) with a reference class extrapolation chamber are dealt with in detail, the use of other measurement systems and measurements in other geometries are also described, although in less detail. The ambient dose equivalent, H*(10) as used for area monitoring of strongly penetrating radiation is not an appropriate quantity for any beta radiation, even for that penetrating a 10 mm thick layer of ICRU tissue (i.e. Emax greater than 2 MeV). If adequate protection is provided at 0,07 mm, only rarely will one be concerned with other depths, for example 3 mm. ISO 6980-2:2004 is geared towards organizations wishing to establish reference-class dosimetry capabilities for beta particles, and serves as a guide to the performance of dosimetry with the reference class extrapolation chamber for beta-particle dosimetry in other fields. Guidance is also provided on the statement of measurement uncertainties.

ISO 6980-1:2006 specifies the requirements for reference beta radiation fields produced by radionuclide sources to be used for the calibration of personal and area dosimeters and dose-rate meters to be used for the determination of the quantities Hp(0,07) and H'(0,07), and for the determination of their response as a function of beta particle energy and angle of incidence. It gives the characteristics of radionuclides that have been used to produce reference beta radiation fields, gives examples of suitable source constructions and describes methods for the measurement of the residual maximum beta particle energy and the dose equivalent rate at a depth of 0,07 mm in the International Commission on Radiation Units and Measurements (ICRU) sphere. The energy range involved lies between 66 keV) and 3,6 MeV and the dose equivalent rates are in the range from about 10-5Sv h-1 to at least 10 Sv h-1. In addition, for some sources variations of the dose equivalent rate as a function of the angle of incidence are given. ISO 6980-1:2006 proposes two series of beta reference radiation fields from which the radiation necessary for determining the characteristics (calibration and energy and angular dependence of response) of an instrument can be selected. Series 1 reference radiation fields are produced by radionuclide sources used with beam flattening filters designed to give uniform dose equivalent rates over a large area at a specified distance. The proposed sources of 90Sr + 90Y, 85Kr, 204Tl and 147Pm produce maximum dose equivalent rates of approximately 200 mSv h-1. Series 2 reference radiation fields are produced without the use of beam-flattening filters, which allows large area planar sources and a range of source-to-calibration plane distances to be used. Close to 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. The radionuclides used are those of series 1 with the addition of the radionuclides 14C and 106Ru + 106Rh; these sources produce dose equivalent rates of up to 10 Sv h-1.

ISO 6980-3:2006 describes procedures for calibrating and determining the response of dosemeters and doserate meters in terms of the International Commission on Radiation Units and Measurements (ICRU) operational quantities, that is, the directional dose equivalent and the personal dose equivalent, for radiation protection purposes. In addition to the description of calibration procedures, this part of ISO 6980-3:2006 includes recommendations for appropriate phantoms and the way to determine appropriate conversion coefficients. Guidance is provided on the statement of measurement uncertainties and the preparation of calibration records and certificates.