Quantification of interplay effects of scanned particle beams and moving targets
Quantification of interplay effects of scanned particle beams and moving targets
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DOI：
10.1088/0031-9155/53/9/003
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发表时间：
2008-05-07
影响因子：
3.5
通讯作者：
Rietzel, Eike
中科院分区：
文献类型：
--
作者：
Bert, Christoph;Groezinger, Sven O.;Rietzel, Eike
扫描粒子束和目标运动会发生干涉。这种相互作用导致剂量分布恶化。进行实验和治疗计划研究来研究相互作用。使用不同运动参数的移动射线照相胶片进行实验。分析所得剂量分布的均匀性和剂量覆盖范围。治疗计划研究基于五名肺部肿瘤患者的时间分辨计算机断层扫描（4DCT）数据。对考虑呼吸运动的治疗计划进行了优化，并计算了每位患者 108 个不同运动参数的剂量分布。单个部分的数据分析基于剂量体积直方图和计划剂量的 95% 覆盖的体积。在实验和治疗计划研究中，相互作用恶化了剂量一致性和均匀性（1-标准差/平均值）。对于大约 15 mm 的运动幅度，射线照相胶片上的均匀性低于大约 80%。对于基于患者数据的治疗计划研究，接受至少 95% 处方剂量的目标体积平均（标准差）为 71.0% (14.2%)。扫描粒子束和移动目标的相互作用对最终的剂量分布有严重影响。分次治疗可能至少减轻部分相互作用的影响。然而，特别是对于小分数，例如。 g。在低分割中，用扫描粒子束处理移动目标需要运动缓解技术，例如重新扫描、选通或跟踪。
Scanned particle beams and target motion interfere. This interplay leads to deterioration of the dose distribution. Experiments and a treatment planning study were performed to investigate interplay. Experiments were performed with moving radiographic films for different motion parameters. Resulting dose distributions were analyzed for homogeneity and dose coverage. The treatment planning study was based on the time-resolved computed tomography (4DCT) data of five lung tumor patients. Treatment plans with margins to account for respiratory motion were optimized, and resulting dose distributions for 108 different motion parameters for each patient were calculated. Data analysis for a single fraction was based on dose-volume histograms and the volume covered with 95% of the planned dose. Interplay deteriorated dose conformity and homogeneity (1-standard deviation/mean) in the experiments as well as in the treatment-planning study. The homogeneity on radiographic films was below approximate to 80% for motion amplitudes of approximate to 15 mm. For the treatment-planning study based on patient data, the target volume receiving at least 95% of the prescribed dose was on average ( standard deviation) 71.0% (14.2%). Interplay of scanned particle beams and moving targets has severe impact on the resulting dose distributions. Fractionated treatment delivery potentially mitigates at least parts of these interplay effects. However, especially for small fraction numbers, e. g. hypo-fractionation, treatment of moving targets with scanned particle beams requires motion mitigation techniques such as rescanning, gating, or tracking.