The influence of cooling rate on the accuracy of normoxic polymer gel dosimeters
- 25 April 2007
- journal article
- Published by IOP Publishing in Physics in Medicine & Biology
- Vol. 52 (10), 2719-2728
- https://doi.org/10.1088/0031-9155/52/10/006
Abstract
Polymer gel dosimeters offer a wide range of applications in the three-dimensional verification of complex radiation dose distributions such as in intensity-modulated radiotherapy (IMRT). With the release of polymer gel dosimeters that can be fabricated in normal atmospheric ('normoxic') conditions, the gel manufacturing process has been significantly simplified. Gel dosimeters are calibrated by use of a series of calibration vials irradiated with known doses or by use of a calibration phantom with a known dose distribution. The overall accuracy of the polymer gel dosimeters is determined by different dosimetric properties. In this study, we show the influence of the temperature history during storage of the gel dosimeter on the dose response curve for two gel dosimeters using the monomers acrylamide/N,N'-methylene-bis-acrylamide (nPAG) and methacrylic acid (nMAG) respectively and bis[tetrakis(hydroxymethyl)phosphonium]sulphate (THP) as antioxidant in both gel dosimeters. This study reveals that differences in temperature history after fabrication of normoxic polymer gel dosimeters may compromise the dosimetric accuracy. It was found that the acrylamide based gel dosimeter (nPAG) is less dependent on the post-manufacture temperature history than the methacrylic acid based gel dosimeter (nMAG). The importance of an equal temperature history for the gel dosimeter and calibration vials is emphasized by this study. A reproducibility study has also been performed on the nPAG gel dosimeter when additional efforts are made to control the temperature changes upon cooling.This publication has 6 references indexed in Scilit:
- The fundamental radiation properties of normoxic polymer gel dosimeters: a comparison between a methacrylic acid based gel and acrylamide based gelsPhysics in Medicine & Biology, 2006
- On the accuracy of monomer/polymer gel dosimetry in the proximity of a high-dose-rate192Ir sourcePhysics in Medicine & Biology, 2001
- Effects of glass and backscatter on measurement of absorbed dose in polyacrylamide gel (PAG) dosimetersPhysics in Medicine & Biology, 2000
- The value of the PinPoint ion chamber for characterization of small field segments used in intensity-modulated radiotherapyPhysics in Medicine & Biology, 2000
- An investigation of the chemical stability of a monomer/polymer gel dosimeterPhysics in Medicine & Biology, 2000
- Three-dimensional dosimetry using polymer gel and magnetic resonance imaging applied to the verification of conformal radiation therapy in head-and-neck cancerRadiotherapy and Oncology, 1998