Department of Medical Physics, Shonan Kamakura General Hospital, Kamakura, Japan.
Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan.
In Vivo. 2024 Nov-Dec;38(6):3059-3067. doi: 10.21873/invivo.13790.
BACKGROUND/AIM: In spot-scanning proton therapy, intra-fractional anatomical changes by organ movement can lead to deterioration in dose distribution due to beam range variation. To explore a more robust treatment planning method, this study evaluated the dosimetric characteristics and robustness of two proton therapy planning methods for liver cancer.
Two- or three-field treatment plans were created for 11 patients with hepatocellular carcinoma or metastatic liver cancer using a single-field uniform dose (SFUD) technique. The plans were optimized using either beam-specific planning target volume (BSPTV) or worst-case optimization (WCO). The target coverage for the gross tumor volume (GTV), planning target volume (PTV), and organs at risk (OAR) parameters related to toxicity were calculated from the perturbed dose distributions, considering setup and range uncertainties. Statistical analyses of the BSPTV and WCO plans were performed using the Wilcoxon signed-rank sum test (p<0.05). The calculation times for a single optimization process were also recorded and compared.
The robustness of the WCO plans in the worst-case scenario was significantly higher than that of the BSPTV plan in terms of GTV target coverage, prevention of maximum dose increase to the gastrointestinal tract, and the dose received by normal liver regions. However, there were no significant differences in PTV, and the calculation time required to create the WCO plan was considerably longer.
In SFUD proton therapy for liver cancer, the WCO plans required a longer optimization time but exhibited superior robustness in GTV coverage and sparing of OARs.
背景/目的：在点扫描质子治疗中，器官运动引起的分次内解剖变化会导致由于束射程变化而导致剂量分布恶化。为了探索更稳健的治疗计划方法，本研究评估了两种肝癌质子治疗计划方法的剂量学特征和稳健性。
使用单野均匀剂量（SFUD）技术为 11 名肝细胞癌或转移性肝癌患者创建了两野或三野治疗计划。使用束特异性计划靶区（BSPTV）或最坏情况优化（WCO）对计划进行优化。从受扰剂量分布中计算出与毒性相关的大体肿瘤体积（GTV）、计划靶区（PTV）和危及器官（OAR）参数的靶区覆盖，考虑到设置和射程不确定性。使用 Wilcoxon 符号秩和检验（p<0.05）对 BSPTV 和 WCO 计划进行统计分析。还记录并比较了单个优化过程的计算时间。
在最坏情况下，WCO 计划的稳健性明显高于 BSPTV 计划，在 GTV 靶区覆盖、防止胃肠道最大剂量增加以及正常肝区接受的剂量方面。然而，PTV 没有显著差异，创建 WCO 计划所需的计算时间要长得多。
在肝癌的 SFUD 质子治疗中，WCO 计划需要更长的优化时间，但在 GTV 覆盖和保护 OAR 方面具有更好的稳健性。
