Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark.
Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
Acta Oncol. 2021 May;60(5):598-604. doi: 10.1080/0284186X.2021.1892181. Epub 2021 Mar 1.
Proton therapy (PT) is sensitive towards anatomical changes that may occur during a treatment course. The aim of this study was to investigate if anatomically robust PT (ARPT) plans incorporating patient-specific target motion improved target coverage while still sparing normal tissues, when applied on locally advanced prostate cancer patients where pelvic irradiation is indicated.
A planning computed tomography (CT) scan used for dose calculation and two additional CTs (acquired on different days) were used to make patient-specific targets for the ARPT plans on the eight included patients. The plans were compared to a conventional robust PT plan and a volumetric modulated arc therapy (VMAT) photon plan, which were derived from the planning CT (pCT). Worst-case robust optimisation was used for all proton plans with a setup uncertainty of 5 mm and a range uncertainty of 3.5%. Target coverage (V95% and D95%) and normal tissue doses (V5-75 Gy) were evaluated on 6-8 rCTs per patient.
The ARPT plans improved the prostate target coverage for the most challenging patient compared to conventional robust PT plans (20% point increase for V95% and 31 Gy increase for D95%). Across the whole cohort the estimated mean value for V95% was 97% for the ARPT plans and 95% for the conventional robust PT plans. The ARPT plans had a slight, statistically insignificant increase in normal tissue doses compared to the conventional robust proton plans. Compared to VMAT, the ARPT plans significantly reduced the normal tissue doses in the low-to-intermediate dose range.
While both proton plans reduced the low-to-intermediate normal tissue doses compared to VMAT, ARPT plans improved the target coverage for the most challenging patient without significantly increasing the normal tissue doses compared to conventional robust PT plans.
质子治疗（PT）对治疗过程中可能发生的解剖结构变化很敏感。本研究旨在探讨在需要盆腔照射的局部晚期前列腺癌患者中，使用纳入患者特定靶区运动的解剖稳健性 PT（ARPT）计划是否能在保护正常组织的同时改善靶区覆盖。
对 8 名患者使用剂量计算的计划 CT（pCT）扫描和另外两次（在不同日期采集）CT 扫描，为 ARPT 计划制作患者特定的靶区。将这些计划与传统稳健 PT 计划和容积调制弧形治疗（VMAT）光子计划进行比较，后者是从 pCT 中衍生而来的。对所有质子计划使用最坏情况稳健优化，设定不确定性为 5mm，范围不确定性为 3.5%。对每位患者的 6-8 次 rCT 评估靶区覆盖率（V95%和 D95%）和正常组织剂量（V5-75Gy）。
与传统稳健 PT 计划相比，ARPT 计划改善了最具挑战性患者的前列腺靶区覆盖率（V95%增加 20%，D95%增加 31Gy）。在整个队列中，ARPT 计划的 V95%估计平均值为 97%，传统稳健 PT 计划为 95%。与传统稳健质子计划相比，ARPT 计划的正常组织剂量略有增加，但无统计学意义。与 VMAT 相比，ARPT 计划显著降低了低至中等剂量范围内的正常组织剂量。
虽然质子计划都降低了低至中等正常组织剂量，但与传统稳健 PT 计划相比，ARPT 计划改善了最具挑战性患者的靶区覆盖率，且正常组织剂量无明显增加。
