Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland.
Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland.
Int J Radiat Oncol Biol Phys. 2017 Mar 1;97(3):616-623. doi: 10.1016/j.ijrobp.2016.11.013. Epub 2016 Nov 16.
To estimate the frequency and impact of anatomic changes on the delivered dose in pencil beam scanning proton therapy, to assess the need for repeat CT scanning and adaptive replanning.
A total of 730 patients treated at Paul Scherrer Institut between 2007 and 2014 were included in this study, for which the number of patients who had control CT scans and who were replanned as a result of anatomic changes was analyzed. For those that were replanned, the nominal dose distributions (originally optimized on the planning CT scan) were recalculated on the replanning CT scan and differences evaluated using standard dose metrics for planning target volumes and clinical target volumes and organs at risk (OARs).
Control CT studies were acquired for 244 patients (33.5%), and replanning was deemed clinically necessary for 40 (16%) of these (5.5% of the total cohort). The OARs and target dose differences between the nominal and recalculated dose distributions were found to be strongly dependent on the subgroup of patients. Nevertheless, dose differences were found to be ≤ 5% for 88% of all analyzed OARs, and planning target volume/clinical target volume V95% was reduced by ≤5% in 87%/90% of cases.
Despite anatomic variations, clinically delivered plans have been found to be robust to anatomic changes, with replanning being deemed necessary in only a small number of cases. However, because the dosimetric effect of such changes can be quite large for some cases, they have to be monitored and evaluated on an individual basis.
评估解剖结构变化对笔形束扫描质子治疗中剂量分布的影响频率和程度，以确定是否需要重复 CT 扫描和自适应计划调整。
本研究共纳入了 2007 年至 2014 年在保罗谢勒研究所接受治疗的 730 名患者，分析了因解剖结构变化而进行了控制 CT 扫描和计划调整的患者数量。对于那些需要重新计划的患者，将在计划 CT 扫描上进行优化的名义剂量分布（最初优化）在重新计划 CT 扫描上重新计算，并使用标准剂量指标评估计划靶区和临床靶区以及危及器官（OARs）的剂量差异。
对 244 名患者（33.5%）进行了控制 CT 研究，其中 40 名（16%）被认为需要临床重新计划（占总队列的 5.5%）。名义剂量分布和重新计算剂量分布之间的 OAR 和靶区剂量差异被发现强烈依赖于患者亚组。尽管如此，在所有分析的 OAR 中，88%的剂量差异都≤5%，在 87%/90%的病例中，计划靶区/临床靶区 V95%减少了≤5%。
尽管存在解剖结构变化，但临床实施的治疗计划在解剖结构变化方面表现出较强的稳健性，只有少数情况下需要重新计划。然而，由于这些变化的剂量学影响在某些情况下可能相当大，因此必须对其进行个体化监测和评估。
