Erasmus MC Cancer Institute, Department of Radiation Oncology, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
Erasmus MC Cancer Institute, Department of Radiation Oncology, University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
Radiother Oncol. 2022 Nov;176:68-75. doi: 10.1016/j.radonc.2022.09.011. Epub 2022 Sep 20.
In intensity modulated proton therapy (IMPT), the impact of setup errors and anatomical changes is commonly mitigated by robust optimization with population-based setup robustness (SR) settings and offline replanning. In this study we propose and evaluate an alternative approach based on daily plan selection from patient-specific pre-treatment established plan libraries (PLs). Clinical implementation of the PL strategy would be rather straightforward compared to daily online re-planning.
For 15 head-and-neck cancer patients, the planning CT was used to generate a PL with 5 plans, robustly optimized for increasing SR: 0, 1, 2, 3, 5 mm, and 3% range robustness. Repeat CTs (rCTs) and realistic setup and range uncertainty distributions were used for simulation of treatment courses for the PL approach, treatments with fixed SR (fSR) and a trigger-based offline adaptive schedule for 3 mm SR (fSROfA). Daily plan selection in the PL approach was based only on recomputed dose to the CTV on the rCT.
Compared to using fSR and fSROfA, the risk of xerostomia grade ≥ II & III and dysphagia ≥ grade III were significantly reduced with the PL. For 6/15 patients the risk of xerostomia and/or dysphagia ≥ grade II could be reduced by > 2% by using PL. For the other patients, adherence to target coverage constraints was often improved. fSROfA resulted in significantly improved coverage compared to PL for selected patients.
The proposed PL approach resulted in overall reduced NTCPs compared to fSR and fSROfA at limited cost in target coverage.
在强度调制质子治疗（IMPT）中，通常通过基于人群的设置稳健性（SR）设置和离线重新计划的强大优化来减轻设置误差和解剖结构变化的影响。在这项研究中，我们提出并评估了一种替代方法，该方法基于从患者特定的预处理建立的计划库（PL）中选择每日计划。与每日在线重新计划相比，PL 策略的临床实施将更加简单。
对于 15 名头颈部癌症患者，使用计划 CT 生成具有 5 个计划的 PL，这些计划针对增加 SR 进行了稳健优化：0、1、2、3、5mm 和 3%范围稳健性。重复 CT（rCT）和现实的设置和范围不确定性分布用于模拟 PL 方法、固定 SR（fSR）和触发式离线自适应计划（fSROfA）的 3mm SR 的治疗课程。PL 方法中的每日计划选择仅基于 rCT 上重新计算的 CTV 剂量。
与使用 fSR 和 fSROfA 相比，PL 显著降低了口干症等级≥Ⅱ级和Ⅲ级和吞咽困难等级≥Ⅲ级的风险。对于 6/15 名患者，使用 PL 可以将口干症和/或吞咽困难等级≥Ⅱ级的风险降低超过 2%。对于其他患者，通常可以改善对目标覆盖率约束的遵守。对于选定的患者，fSROfA 导致覆盖范围明显优于 PL。
与 fSR 和 fSROfA 相比，PL 方法总体上降低了 NTCPs，同时在目标覆盖率方面的成本有限。
