Title: Calibration of the Prompt Gamma Ray Analysis Facility in Petten for 10B Concentrations up to 2000 ppm
Citation: Proceedings of the 13th International Congress on Neutron Capture Therapy, ISBN: 88-8286-167-8 vol. 88-8286-167-8 p. 252-256
Publisher: ENEA
Publication Year: 2008
JRC Publication N°: JRC48350
URI: http://www.enea.it/com/ingl/New_ingl/publications/editions.html
Type: Contributions to Conferences
Abstract: At the BNCT facility in Petten, the Netherlands, 10B concentrations in biological materials are measured with the Prompt Gamma Ray Analyses facility, which is situated at one of the horizontal beam tubes of the High Flux Reactor. Up until recently, the quantities of 10B are determined in small samples (20 mg - 1 g) of blood, urine and/or tissues, following calibration of the facility, using certified 10B solutions, with a 10B-concentration ranging from 0 ppm up to 210 ppm and by fitting a calibration curve of a second order polynomial through 8 measurements. The concentrations of blood and tissue were always below the 210 ppm and therefore within the measured calibration range. Recently, urine samples containing up to 2800 ppm were investigated. These values are outside the calibrated range and in a first approach results were based on extrapolation of the fitted curve. For this study, newly certified 10B solutions between 374 ppm and 1972 ppm were measured in order to verify if the previous extrapolation is justified. This appears not to be the case and two calibration curves are necessary. We found that for a 10B-concentration of more than 300 ppm another fitted third order polynomial is needed as beyond this level, the self-shielding of 10B interacts with the measurements. This result is confirmed by simulating the whole set-up with MCNP. With the new calibration curve, materials from patients were analysed retrospectively, resulting in differences of the 10B-concentrations of up to 16%, when compared to the former calibration curve.
JRC Institute:Institute for Energy and Transport

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