Technical Note: First report on an in vivo range probing quality control procedure for scanned proton beam therapy in head and neck cancer patients
Technical Note: First report on an in vivo range probing quality control procedure for scanned proton beam therapy in head and neck cancer patients
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DOI：
10.1002/mp.14713
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发表时间：
2021-02-06
期刊：
影响因子：
3.8
通讯作者：
Both, Stefan
中科院分区：
文献类型：
--
作者：
Meijers, Arturs;Oria, Carmen Seller;Both, Stefan
目的质子治疗提供高度适形剂量分布的能力受到射程不确定性的影响。这项工作的目的是应用范围探测（RP），一种形式的质子射线照相为基础的质量控制（QC）程序的范围准确性评估在头部和颈部癌症（HNC）patients in a clinical setting.Methods和材料本研究包括7 HNC患者。使用多层电离室（MLIC）进行RP采集。每例患者，在治疗的前两周内，在获得重复CT扫描的当天获得两个RP帧。每个RP帧，采集治疗等中心周围81个点的积分深度剂量（IDD）曲线。范围误差被确定为治疗计划系统中计算的IDD与MLIC测量的剩余范围之间的差异。距离误差相对于单个质子点的水等效路径长度。除了完整的测量帧的报告结果，分析，不包括范围误差的贡献，由于解剖结构的变化，presented.Results测量和计算的范围之间的差异较小时，执行RP计算的一天特定的患者解剖结构，而不是规划CT。患者特定的范围评估显示，在3%（1.5标准差）内的解剖学一致的区域斑点的计算和测量范围之间的协议。结论的RP为基础的QC程序在临床实践中实施的HNC患者的结果已被证明。测量和模拟质子范围的协议确认了3%的不确定性裕度稳健优化。解剖变异显示出对范围准确性的主要影响，激励努力实现自适应放射治疗。
Purpose The capability of proton therapy to provide highly conformal dose distributions is impaired by range uncertainties. The aim of this work is to apply range probing (RP), a form of a proton radiography-based quality control (QC) procedure for range accuracy assessment in head and neck cancer (HNC) patients in a clinical setting.Methods and Materials This study included seven HNC patients. RP acquisition was performed using a multi-layer ionization chamber (MLIC). Per patient, two RP frames were acquired within the first two weeks of treatment, on days when a repeated CT scan was obtained. Per RP frame, integral depth dose (IDD) curves of 81 spots around the treatment isocenter were acquired. Range errors are determined as a discrepancy between calculated IDDs in the treatment planning system and measured residual ranges by the MLIC. Range errors are presented relative to the water equivalent path length of individual proton spots. In addition to reporting results for complete measurement frames, an analysis, excluding range error contributions due to anatomical changes, is presented.Results Discrepancies between measured and calculated ranges are smaller when performing RP calculations on the day-specific patient anatomy rather than the planning CT. The patient-specific range evaluation shows an agreement between calculated and measured ranges for spots in anatomically consistent areas within 3% (1.5 standard deviation).Conclusions The results of an RP-based QC procedure implemented in the clinical practice for HNC patients have been demonstrated. The agreement of measured and simulated proton ranges confirms the 3% uncertainty margin for robust optimization. Anatomical variations show a predominant effect on range accuracy, motivating efforts towards the implementation of adaptive radiotherapy.