The DosiMap, a new 2D scintillating dosimeter for IMRT quality assurance: Characterization of two Cerenkov discrimination methods
The DosiMap, a new 2D scintillating dosimeter for IMRT quality assurance: Characterization of two Cerenkov discrimination methods
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DOI：
10.1118/1.2897966
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发表时间：
2008-05-01
期刊：
影响因子：
3.8
通讯作者：
Leroux, T.
中科院分区：
文献类型：
--
作者：
Frelin, A-M.;Fontbonne, J-M.;Leroux, T.
新的放射治疗技术，如IMRT，由于其高度适形的剂量分布，目前显着的效率。由于其剂量分布的复杂性（高梯度、小照射野、低剂量分布等），要求比传统放射治疗更好的精度质量保证，以便将输送剂量的一致性与计划剂量分布进行比较，并保证治疗质量。目前，这种控制主要通过电离室矩阵、二极管探测器、剂量测定胶片、射野成像或剂量测定凝胶来进行。另一种方法是闪烁剂量测定法，这是在过去15年中主要通过闪烁纤维装置发展起来的。尽管与其他方法相比具有许多优点，但它仍然处于常规剂量测定的实验水平，因为照射下产生的切伦科夫辐射代表了重要的干效应。一种新的2D水当量放射剂量计，DosiMap和两种不同的Cerenkov判别方法是与卡昂的Physique Corpusculaire，综合癌症中心Francois Baclesse和ELDIM公司合作开发的，在MAESTRO欧洲项目的框架内。DosiMap由放置在透明聚苯乙烯体模内的塑料薄片组成。在照射下产生的光分布由CCD相机记录。我们的第一个切伦科夫鉴别技术是减法。它使用放置在闪烁体前面的棋盘图案，其提供仅包含切伦科夫光的背景信号。我们的第二种辨别技术是比色法。它执行光信号的光谱分析，这允许展开切伦科夫辐射和闪烁。我们的DosiMap原型进行了测试，并对两种判别方法的性能进行了评估。剂量测量进行了比较与剂量图和剂量测定膜的三种不同的照射配置显示的差异小于3.5%的2毫米的空间分辨率。两个创新的歧视解决方案被证明是从切伦科夫辐射分离的闪烁。它还表明，剂量图，这是水当量，快速，用户友好，是一个非常有前途的放射治疗质量保证的工具。(C)2008年美国医学物理学家协会。
New radiation therapy techniques such as IMRT present significant efficiency due to their highly conformal dose distributions. A consequence of the complexity of their dose distributions (high gradients, small irradiation fields, low dose distribution, ...) is the requirement for better precision quality assurance than in classical radiotherapy in order to compare the conformation of the delivered dose with the planned dose distribution and to guarantee the quality of the treatment. Currently this control is mostly performed by matrices of ionization chambers, diode detectors, dosimetric films, portal imaging, or dosimetric gels. Another approach is scintillation dosimetry, which has been developed in the last 15 years mainly through scintillating fiber devices. Despite having many advantages over other methods it is still at an experimental level for routine dosimetry because the Cerenkov radiation produced under irradiation represents an important stem effect. A new 2D water equivalent scintillating dosimeter, the DosiMap, and two different Cerenkov discrimination methods were developed with the collaboration of the Laboratoire de Physique Corpusculaire of Caen, the Comprehensive Cancer Center Francois Baclesse, and the ELDIM Co., in the frame of the MAESTRO European project. The DosiMap consists of a plastic scintillating sheet placed inside a transparent polystyrene phantom. The light distribution produced under irradiation is recorded by a CCD camera. Our first Cerenkov discrimination technique is subtractive. It uses a chessboard pattern placed in front of the scintillator, which provides a background signal containing only Cerenkov light. Our second discrimination technique is colorimetric. It performs a spectral analysis of the light signal, which allows the unfolding of the Cerenkov radiation and the scintillation. Tests were carried out with our DosiMap prototype and the performances of the two discrimination methods were assessed. The comparison of the dose measurements performed with the DosiMap and with dosimetric films for three different irradiation configurations showed discrepancies smaller than 3.5% for a 2 mm spatial resolution. Two innovative discrimination solutions were demonstrated to separate the scintillation from the Cerenkov radiation. It was also shown that the DosiMap, which is water equivalent, fast, and user friendly, is a very promising tool for radiotherapy quality assurance. (C) 2008 American Association of Physicists in Medicine.