Performance of radiophotoluminescence personal dosimeters in terms of the ICRU Report 95's operational quantities. (August 2022) - Bossin, Lily
Abstract: The objective of this work is to assess the photon energy and angle response of the radiophotoluminescence (RPL) personal dosimetry system used at the Paul Scherrer Institute (PSI) in terms of the operational quantities for external radiation exposure personal dose, H p, and personal absorbed dose in local skin, D local skin, defined in the Report 95 of the International Commission on Radiation Measurements and Units (ICRU). The RPL responses in terms of the "new" ICRU Report 95 quantities to a range of photon energies and irradiation angles were calculated using the RPL responses in terms of the personal dose equivalent H p ( 10 ) and H p ( 0 . 07 ) from the ICRU Report 51, previously obtained during commissioning of the RPL system, and the conversion coefficients from air kerma to the various operational quantities. The indicated value provided by the current dosimetry algorithm over-estimates the personal dose, H p, in the low-energy range (¡ 33 keV), whereas the estimation for the personal absorbed dose in local skin, D local skin, with the current system is satisfactory. A new dosimetry algorithm was developed making use of the five signals obtained from the RPL detectors, corresponding to the signal from regions of RPL glass under five different filters, to improve the H p estimation by the RPL dosimeters. The results indicate that, in this case, the new algorithm may be sufficient to achieve satisfactory photon energy and angle response in terms of the ICRU Report 95 quantity H p without a physical redesign of the dosimeter badges. A few photon mixed fields were also investigated, but a complete algorithm for photon-beta mixed field remains to be developed. Highlights: Photon energy and angle response of an RPL system for H p and D local skin calculated. H p exhibited an over-response in the energy range < 33 keV with the present system. A new dose calculation algorithm was designed to suppress this over-response.