Molecular Imaging, Radiotherapy and Oncology (MIRO), UCLouvain, Brussels, Brussels, Belgium.
Department of Radiation Oncology (MAASTRO), GROW - School for Oncology, Maastricht University Medical Centre+, Netherlands.
Radiother Oncol. 2022 May;170:190-197. doi: 10.1016/j.radonc.2022.03.011. Epub 2022 Mar 25.
Intensity modulated proton therapy (IMPT) is highly sensitive to anatomical variations which can cause inadequate target coverage during treatment. This study compares not-adapted (NA) robust plans to two adaptive IMPT methods - a fully-offline adaptive (FOA) and a simplified automatic online adaptive strategy (dose restoration (DR)) to determine the benefit of DR, in head and neck cancer (HNC).
MATERIAL/METHODS: Robustly optimized clinical IMPT doses in planning-CTs (pCTs) were available for a cohort of 10 HNC patients. During robust re-optimization, DR used isodose contours, generated from the clinical dose on pCTs, and patient specific objectives to reproduce the clinical dose in every repeated-CT(rCT). For each rCT(n = 50), NA, DR and FOA plans were robustly evaluated.
An improvement in DVH-metrics and robustness was seen for DR and FOA plans compared to NA plans. For NA plans, 74%(37/50) of rCTs did not fulfill the CTV coverage criteria (D98%>95%Dprescription). DR improved target coverage, target homogeneity and variability on critical risk organs such as the spinal cord. After DR, 52%(26/50) of rCTs met all clinical goals. Because of large anatomical changes and/or inaccurate patient repositioning, 48%(24/50) of rCTs still needed full offline adaptation to ensure an optimal treatment since dose restoration was not able to re-establish the initial plan quality.
Robust optimization together with fully-automatized DR avoided offline adaptation in 52% of the cases. Implementation of dose restoration in clinical routine could ensure treatment plan optimality while saving valuable human and material resources to radiotherapy departments.
强度调制质子治疗（IMPT）对解剖结构的变化非常敏感，这些变化可能导致治疗过程中靶区覆盖不足。本研究比较了非自适应（NA）稳健计划和两种自适应 IMPT 方法——完全离线自适应（FOA）和简化自动在线自适应策略（剂量恢复（DR）），以确定 DR 在头颈部癌症（HNC）中的获益。
材料/方法：为 10 例 HNC 患者提供了稳健优化的计划 CT（pCT）临床 IMPT 剂量。在稳健重新优化过程中，DR 使用从 pCT 上的临床剂量生成的等剂量轮廓，并使用患者特定的目标在每个重复 CT（rCT）中重现临床剂量。对于每个 rCT（n=50），进行了 NA、DR 和 FOA 计划的稳健评估。
与 NA 计划相比，DR 和 FOA 计划在剂量体积直方图（DVH）指标和稳健性方面有所改善。对于 NA 计划，74%（37/50）的 rCT 未能满足CTV 覆盖标准（D98%>95%Dprescription）。DR 改善了靶区覆盖、靶区均匀性和关键风险器官（如脊髓）的变异性。经过 DR 后，52%（26/50）的 rCT 满足了所有临床目标。由于解剖结构的大变化和/或患者定位不准确，48%（24/50）的 rCT 仍需要完全离线自适应，以确保治疗计划的最佳化，因为剂量恢复无法重新建立初始计划质量。
稳健优化加上全自动的 DR 在 52%的情况下避免了离线自适应。在临床常规中实施剂量恢复可以确保治疗计划的最佳化，同时为放射治疗部门节省宝贵的人力和物力资源。
