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Sci‐PM Fri ‐ 07: The development and testing of an all‐glass vessel for absorbed dose to water
Author(s) -
Ross C,
Klassen N,
McEwen M
Publication year - 2005
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2031039
Subject(s) - absorbed dose , exothermic reaction , endothermic process , materials science , nuclear engineering , inert , calorimetry , inert gas , aqueous solution , dosimetry , environmental science , chemistry , composite material , thermodynamics , adsorption , nuclear medicine , physics , medicine , engineering , organic chemistry
Calorimetry is widely used for establishing primary standards for absorbed dose. The advantage of using water as a calorimetric material is that it gives directly the absorbed dose to water, which is the quantity of interest for radiation therapy. Unfortunately, radiation‐induced chemical reactions in the water (sometimes with impurities) may be exothermic or endothermic, thus contributing to an unknown “heat defect”. Calculations and measurements show that there are a few aqueous systems for which the heat defect can be established with small uncertainty. In particular, the heat defect of pure water saturated with an inert gas or with hydrogen gas is expected to be zero after an accumulated dose of a few gray. The need for maintaining high purity water systems and techniques for cleaning, filling and sealing vessels contributes significantly to the complexity associated with water calorimetry. In an effort to overcome this limitation, we have developed a vessel in which only glass comes in contact with the water and which is flame‐sealed after being filled and saturated with an appropriate gas. We have measured the response of one such vessel over several years and found it to be stable and consistent with expected results. We believe these all‐glass vessels will ease the effort of maintaining water calorimeters as absorbed dose standards and may be used for direct comparisons among laboratories with similar devices.