An absorbed dose to water standard for HDR 192Ir brachytherapy sources based on water calorimetry: numerical and experimental proof-of-principle

Medical Physics
Arman SarfehniaJ Seuntjens

Abstract

Water calorimetry is an established technique for absorbed dose to water measurements in external beams. In this paper, the feasibility of direct absorbed dose measurements for high dose rate (HDR) iridium-192 (192Ir) sources using water calorimetry is established. Feasibility is determined primarily by a balance between the need to obtain sufficient signal to perform a reproducible measurement, the effect of heat loss on the measured signal, and the positioning uncertainty affecting the source-detector distance. The heat conduction pattern generated in water by the Nucletron microSelectron-HDR 192Ir brachytherapy source was simulated using COMSOL MULTIPHYSICS software. Source heating due to radiation self-absorption was calculated using EGSnrcMP. A heat-loss correction k(c) was calculated as the ratio of the temperature rise under ideal conditions to temperature rise under realistic conditions. The calorimeter setup used a parallel-plate calorimeter vessel of 79 mm diameter and 1.12 mm thick front and rear glass windows located 24 mm apart. Absorbed dose was measured with two sources with nominal air kerma strengths of 38 000 and 21 000 U, at source-detector separations ranging from 24.7 to 27.6 mm and irradiation times of 36....Continue Reading

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Citations

Apr 22, 2009·Medical Physics·Renato Di Prinzio, Carlos Eduardo DeAlmeida
May 13, 2014·The British Journal of Radiology·T Sander
Nov 4, 2008·Medical Physics·Bruce R ThomadsenAli S Meigooni
Dec 19, 2014·PloS One·Carlos Eduardo deAlmeidaMario Antônio Bernal
Oct 19, 2019·Physics in Medicine and Biology·J RenaudJ Seuntjens

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