Correction factors for two new reference beta radiation fields

Abstract

Several correction factors for two new reference beta-particle radiation fields complementing ISO 6980 have been measured and calculated for both primary beta dosimetry and the operational quantities in radiation protection. The following correction factors for primary beta dosimetry for the determination of the absorbed dose to tissue, Dt, have been determined by calculations: kba for backscatter from the collecting electrode, kpe for perturbation by the chamber’s side walls, kih for inhomogeneity inside the collecting volume, kSta for the stopping power ratio at different phantom depths, and kSA for the use of the Spencer-Attix theory, while the following have been measured: kbr for the effect of bremsstrahlung and kabs for variations in the attenuation and scattering of beta particles between the source and the collecting volume due to variations from reference conditions and for differences of the entrance window to a tissue-equivalent thickness of 0.07 mm. Furthermore, calculations were undertaken to determine the following correction factors to assess the operational quantities Hp(0.07), Hp(3), H′(0.07), and H′(3): krod(0.07) for the rod instead of the slab phantom, kcyl(3) for the cylinder instead of the slab phantom, as well as k′(0.07) and k′(3) for the ICRU sphere instead of the slab phantom, while the correction factor for oblique radiation incidence has been measured. The newly determined correction factors were determined in the same way as those for several well-established beta-particle radiation fields described in two earlier publications by the author. Furthermore, they are ready to be implemented in an updated version of the ISO 6980 series and in the software of the Beta Secondary Standard BSS 2.