(Depth-dose curves of the beta reference fields (147)Pm, (85)Kr and (90)Sr/(90)Y produced by the beta secondary standard BSS2.

ABSTRACT

The most common reference fields in beta dosimetry are the ISO 6980 series 1 radiation fields produced by the beta secondary standard BSS2 and its predecessor BSS. These reference fields require sealed beta radiation sources ((147)Pm, (85)Kr or (90)Sr/(90)Y) in combination with a source-specific beam-flattening filter, and are defined only at a given distance from the source. Every radiation sources shipped with the BSS2 is sold with a calibration certificate of the Physikalisch-Technische Bundesanstalt. The calibration workflow also comprises regular depth-dose measurements. This work publishes complete depth-dose curves of the series 1 sources (147)Pm, (85)Kr and (90)Sr/(90)Y in ICRU tissue up to a depth of 11 mm,when all electrons are stopped. For this purpose, the individual depth-dose curves of all BSS2 sources calibrated so far have been determined, i.e. the complete datasets of all BSS2 beta sources have been re-evaluated. It includes 191 depth-dose curves of 116 different sources comprising more than 2200 data points in total. Appropriate analytical representations of the nuclide-specific depth-dose curves are provided for the first time.