Spěváček V, Pilařová K, Končeková J, Konček O
Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Břehová 7, 115 19 Prague 1, Czech Republic.
Phys Med Biol. 2014 Sep 7;59(17):5141-61. doi: 10.1088/0031-9155/59/17/5141. Epub 2014 Aug 20.
In order to decrease the negative influence of oxygen to the response of PAG dosimeters THPC has been added to the gel in the role of scavenger. Apart from the decreased influence of oxygen, THPC also influences other properties of gel dosimeters. This study examines these influences and their quantification. Previous studies have shown that increasing the concentration of THPC causes a decreasing response of the dosimeter (as measured in the relaxation rate R2). Evaluation of the IR spectrum of gels irradiated by a variety of doses has shown that it is caused mostly by the changed structure of the arising polymer, not due to the decreased polymerization. THPC also changes the kinetics of the subsequent reactions in the gel after the end of irradiation. THPC has its influence also on the size of the dose response overshoot that happens in the areas of steep dose gradients. An easy model of action in the gel was suggested, which allows one to estimate the size and kinetics of the changed response of the dosimeter after the end of irradiation depending on the content of THPC, the size of the dose and the dose gradient.
为了降低氧气对PAG剂量计响应的负面影响，已将四羟甲基氯化磷（THPC）作为清除剂添加到凝胶中。除了降低氧气的影响外，THPC还会影响凝胶剂量计的其他特性。本研究考察了这些影响及其定量关系。先前的研究表明，增加THPC的浓度会导致剂量计响应降低（以弛豫率R2衡量）。对不同剂量照射的凝胶的红外光谱评估表明，这主要是由生成的聚合物结构变化引起的，而非聚合作用降低所致。THPC还会改变照射结束后凝胶中后续反应的动力学。THPC对陡峭剂量梯度区域出现的剂量响应过冲大小也有影响。提出了一个凝胶中的简单作用模型，该模型可让人们根据THPC含量、剂量大小和剂量梯度，估算照射结束后剂量计响应变化的大小和动力学。
