title: Investigating potential physicochemical errors in polymer gel dosimeters.
abstract: Measurement errors in polymer gel dosimetry can originate either during irradiation or scanning. One concern related to the exothermic nature of polymerization reaction was that the heat released in polymer gel dosimeters during irradiation modifies their dose response. In this paper, the effect of heat released from the exothermal polymerization reaction on the dose response of a number of dosimeters was studied. In addition, we investigated whether heat-generated geometric distortion existed in newly proposed gel dosimeters that contain highly thermoresponsive polymers. Our results suggest that despite a significant internal temperature increase in some gel compositions, their dose responses are not affected when oxygen is well expelled mechanically from the gel mixture. We also report on significant pre-irradiation instability in some recently developed polymer gel dosimeters but that geometric distortions were not observed. Data obtained by a set of small calibration vials are compared to those obtained from larger phantoms, and potential physicochemical causes of deviations between them are identified.
authors.affiliation: Centre d'imagerie moléculaire de Sherbrooke, Département de médecine nucléaire et radiobiologie, Université de Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Mahbod
authors.initials: M
authors.lastname: Sedaghat
authors.forename: Rachel
authors.initials: R
authors.lastname: Bujold
authors.forename: Martin
authors.initials: M
authors.lastname: Lepage
mesh_terms: D002138:Calibration; D003951:Diagnostic Errors; D004307:Dose-Response Relationship, Radiation; D005782:Gels / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D008768:Methylmethacrylates / Q000737:chemistry*; D019047:Phantoms, Imaging; D011874:Radiometry / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors
chemical_list: D005782:Gels; D008768:Methylmethacrylates