Dose reconstruction for intensity-modulated radiation therapy using a non-iterative method and portal dose image
Dose reconstruction for intensity-modulated radiation therapy using a non-iterative method and portal dose image
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DOI：
10.1088/0031-9155/54/17/010
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发表时间：
2009-09-07
影响因子：
3.5
通讯作者：
Lee, Dohyung
中科院分区：
文献类型：
--
作者：
Yeo, Inhwan Jason;Jung, Jae Won;Lee, Dohyung
提出了一种简单而准确的方法来验证调强放射治疗（IMRT）的输送并重建患者的剂量。该方法基于计算算法，该算法线性地描述了患者体内的小射束和剂量评分体素与来自电子射野成像设备（EPID）的剂量图像之间的物理关系。该关系以剂量响应函数（响应）的形式表示，该函数使用蒙特卡罗（MC）粒子传输技术进行量化。根据由EPID测量的剂量信息，通过逆求解算法来重建所接收的患者剂量。该算法的独特和新颖的非迭代功能使其有别于文献中现有的许多剂量重建方法。本研究详细介绍了该算法，并验证了它的开放和调强放射治疗领域的实验。首先通过MC模拟计算选定场的每个子束的响应。在平坦体模上进行体模内和出射胶片剂量测定。使用计算的响应和算法，出口胶片剂量被用于逆重建体模内剂量，然后将其与测量的体模内剂量进行比较。所有照射野的体模剂量比较显示，给定3%剂量差异和3 mm一致距离的标准，剂量点的通过率高于90%。
A straightforward and accurate method was developed to verify the delivery of intensity-modulated radiation therapy (IMRT) and to reconstruct the dose in a patient. The method is based on a computational algorithm that linearly describes the physical relationship between beamlets and dose-scoring voxels in a patient and the dose image from an electronic portal imaging device (EPID). The relationship is expressed in the form of dose response functions (responses) that are quantified using Monte Carlo (MC) particle transport techniques. From the dose information measured by the EPID the received patient dose is reconstructed by inversely solving the algorithm. The unique and novel non-iterative feature of this algorithm sets it apart from many existing dose reconstruction methods in the literature. This study presents the algorithm in detail and validates it experimentally for open and IMRT fields. Responses were first calculated for each beamlet of the selected fields by MC simulation. In-phantom and exit film dosimetry were performed on a flat phantom. Using the calculated responses and the algorithm, the exit film dose was used to inversely reconstruct the in-phantom dose, which was then compared with the measured in-phantom dose. The dose comparison in the phantom for all irradiated fields showed a pass rate of higher than 90% dose points given the criteria of dose difference of 3% and distance to agreement of 3 mm.