Sensitivity calibration procedures in optical-CT scanning of BANG 3 polymer gel dosimeters.
Sensitivity calibration procedures in optical-CT scanning of BANG 3 polymer gel dosimeters.
复制标题
BANG 3 聚合物凝胶剂量计光学 CT 扫描的灵敏度校准程序。
DOI：
10.1118/1.3298017
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发表时间：
2010
期刊：
影响因子：
3.8
通讯作者：
Maryanski,MarekJ
中科院分区：
文献类型：
--
作者：
Xu,Y;Wuu,Cheng-Shie;Maryanski,MarekJ
BANG®3聚合物凝胶剂量计（MGS Research Inc.，麦迪逊，CT）使用OCTOPUS™激光CT扫描仪（MGS研究公司，麦迪逊，CT）。使用6个直径17 cm和高12 cm的Barex圆筒和18个小玻璃小瓶来容纳凝胶。使用Varian Clinac 2100 EX用6和10 MV光子以及12和16 MeV电子照射凝胶体模。使用三种校准方法获得剂量响应曲线：（a）使用6或10 MV大视场辐照，对18个玻璃小瓶进行0 - 4戈伊梯度剂量辐照后的光密度测量;（B）对Barex圆柱体进行梯度剂量辐照后的光学CT扫描（0.5、1、1.5和2戈伊）;以及（c）12和16 MeV电子场的光学CT扫描与离子室测量的百分比深度剂量（PDD）比较。发现BANG®3凝胶的剂量响应在实验方法的不确定性（约3%）内是线性的且与能量无关。来自四个场辐照（、、和）和PDD匹配方法（和）的线性拟合剂量响应曲线（剂量灵敏度）的斜率在2.2%内一致，表明相同几何形状的体模内凝胶剂量响应具有良好的再现性。从玻璃小瓶的方法的剂量灵敏度是不同的圆柱形Barex phantelines的30%以上，可能是由于在凝胶形成和照射过程中的两种类型的phantelines内的温度差异，和可能的玻璃小瓶壁的氧污染。使用16 MeV电子场PDD匹配方法获得的剂量响应曲线来校准用12 MeV电子场辐照的凝胶体模。使用3%剂量差异和2 mm一致距离标准，对凝胶测量和Eclipse计划系统（Varian Corporation，Palo Alto，CA）的三维剂量分布进行比较和评价。
The dose response of the BANG®3 polymer gel dosimeter (MGS Research Inc., Madison, CT) was studied using the OCTOPUS™ laser CT scanner (MGS Research Inc., Madison, CT). Six 17 cm diameter and 12 cm high Barex cylinders, and 18 small glass vials were used to house the gel. The gel phantoms were irradiated with 6 and 10 MV photons, as well as 12 and 16 MeV electrons using a Varian Clinac 2100EX. Three calibration methods were used to obtain the dose response curves: (a) Optical density measurements on the 18 glass vials irradiated with graded doses from 0 to 4 Gy using 6 or 10 MV large field irradiations; (b) optical‐CT scanning of Barex cylinders irradiated with graded doses (0.5, 1, 1.5, and 2 Gy) from four adjacent photon fields or electron fields; and (c) percent depth dose (PDD) comparison of optical‐CT scans with ion chamber measurements for , 12 and 16 MeV electron fields. The dose response of the BANG®3 gel was found to be linear and energy independent within the uncertainties of the experimental methods (about 3%). The slopes of the linearly fitted dose response curves (dose sensitivities) from the four field irradiations (, , , and ) and the PDD matching methods ( and ) agree within 2.2%, indicating a good reproducibility of the gel dose response within phantoms of the same geometry. The dose sensitivities from the glass vial approach are different from those of the cylindrical Barex phantoms by more than 30%, owing probably to the difference in temperature inside the two types of phantoms during gel formation and irradiation, and possible oxygen contamination of the glass vial walls. The dose response curve obtained from the PDD matching approach with 16 MeV electron field was used to calibrate the gel phantom irradiated with the 12 MeV, electron field. Three‐dimensional dose distributions from the gel measurement and the Eclipse planning system (Varian Corporation, Palo Alto, CA) were compared and evaluated using 3% dose difference and 2 mm distance‐to‐agreement criteria.