Centre d'imagerie moléculaire de Sherbrooke, Département de médecine nucléaire et radiobiologie, Université de Sherbrooke, Sherbrooke, QC, Canada.
Phys Med Biol. 2011 Sep 21;56(18):6083-107. doi: 10.1088/0031-9155/56/18/019. Epub 2011 Aug 26.
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.
在聚合物凝胶剂量测定中，测量误差可能源于辐照或扫描过程中。聚合反应放热的特性引起了人们的关注，因为辐照过程中聚合物凝胶剂量计释放的热量会改变其剂量响应。本文研究了放热聚合反应释放的热量对多种剂量计剂量响应的影响。此外，我们还研究了新提出的含有高热敏聚合物的凝胶剂量计是否存在因热产生的几何变形。结果表明，尽管一些凝胶组成部分的内部温度显著升高，但当凝胶混合物中氧被机械充分排出时，其剂量响应不受影响。我们还报告了一些最近开发的聚合物凝胶剂量计在辐照前存在显著的不稳定性，但没有观察到几何变形。从小校准瓶中获得的数据与从较大的体模中获得的数据进行了比较，并确定了它们之间出现偏差的潜在物理化学原因。
