Spevacek V, Novotny J, Dvorak P, Novotny J, Vymazal J, Cechak T
Czech Technical University in Prague, Faculty of Nuclear Science and Physical Engineering, Department of Dosimetry and Application of Ionizing Radiation, Brehova 7, 110 00 Prague 1, The Czech Republic.
Med Phys. 2001 Nov;28(11):2370-8. doi: 10.1118/1.1410124.
The purpose of this study was to find a physical-mathematical description capable to correct a polymer-gel dosimeter relaxation rate R2-dose response for different temperatures. Four different modifications of polymer-gel dosimeters were used in this study. Samples with polymer-gel dosimeter in glass test vessels were homogeneously irradiated by 60Co gamma photons. A multi-echo sequence with 16 equidistant echoes was used for evaluation of irradiated polymer-gel dosimeters. The sequence parameters were as follows: TR 2000 ms, TE 22.5-360.0 ms, slice thickness 5 mm, FOV 255 mm, one acquisition. The proposed description recommends to subtract R2 response of the nonirradiated dosimeter from the total R2-dose response. The relaxation rate for the irradiated dosimeter can be expressed as a function of temperature and dose. The temperature dependence has an exponential behavior in the measured range. The proposed description allows to correct the measured NMR R2-dose responses for different temperatures.
本研究的目的是找到一种物理 - 数学描述，能够校正聚合物凝胶剂量计在不同温度下的弛豫率R2 - 剂量响应。本研究使用了四种不同改性的聚合物凝胶剂量计。将装有聚合物凝胶剂量计的玻璃测试容器中的样品用60Coγ光子均匀辐照。使用具有16个等距回波的多回波序列来评估辐照后的聚合物凝胶剂量计。序列参数如下：重复时间（TR）2000毫秒，回波时间（TE）22.5 - 360.0毫秒，层厚5毫米，视野（FOV）255毫米，采集一次。所提出的描述建议从总的R2 - 剂量响应中减去未辐照剂量计的R2响应。辐照剂量计的弛豫率可以表示为温度和剂量的函数。在所测量的范围内，温度依赖性呈指数行为。所提出的描述允许校正不同温度下测量的核磁共振R2 - 剂量响应。
