Paul Scherrer Institute, Center for Proton Therapy, Switzerland; Department of Physics, ETH Zurich, Switzerland.
Paul Scherrer Institute, Center for Proton Therapy, Switzerland; Department of Physics, ETH Zurich, Switzerland.
Radiother Oncol. 2021 Jun;159:136-143. doi: 10.1016/j.radonc.2021.03.021. Epub 2021 Mar 23.
A major burden of introducing an online daily adaptive proton therapy (DAPT) workflow is the time and resources needed to correct the daily propagated contours. In this study, we evaluated the dosimetric impact of neglecting the online correction of the propagated contours in a DAPT workflow.
For five NSCLC patients with nine repeated deep-inspiration breath-hold CTs, proton therapy plans were optimised on the planning CT to deliver 60 Gy-RBE in 30 fractions. All repeated CTs were registered with six different clinically used deformable image registration (DIR) algorithms to the corresponding planning CT. Structures were propagated rigidly and with each DIR algorithm and reference structures were contoured on each repeated CT. DAPT plans were optimised with the uncorrected, propagated structures (propagated DAPT doses) and on the reference structures (ideal DAPT doses), non-adapted doses were recalculated on all repeated CTs.
Due to anatomical changes occurring during the therapy, the clinical target volume (CTV) coverage of the non-adapted doses reduces on average by 9.7% (V95) compared to an ideal DAPT doses. For the propagated DAPT doses, the CTV coverage was always restored (average differences in the CTV V95 < 1% compared to the ideal DAPT doses). Hotspots were always reduced with any DAPT approach.
For the patients presented here, a benefit of online DAPT was shown, even if the daily optimisation is based on propagated structures with some residual uncertainties. However, a careful (offline) structure review is necessary and corrections can be included in an offline adaption.
引入在线每日自适应质子治疗（DAPT）工作流程的主要负担是纠正每日传播轮廓所需的时间和资源。在这项研究中，我们评估了在 DAPT 工作流程中忽略传播轮廓在线校正的剂量学影响。
对于五名患有九次重复深呼吸屏气 CT 的 NSCLC 患者，质子治疗计划在计划 CT 上进行优化，以 30 个分次给予 60Gy-RBE。所有重复 CT 均使用六种不同的临床使用的变形图像配准（DIR）算法与相应的计划 CT 进行配准。结构刚性传播和每个 DIR 算法和参考结构均在每个重复 CT 上进行描绘。DAPT 计划使用未经校正的传播结构（传播 DAPT 剂量）和参考结构（理想 DAPT 剂量）进行优化，非自适应剂量在所有重复 CT 上重新计算。
由于治疗过程中发生的解剖变化，与理想 DAPT 剂量相比，非自适应剂量的临床靶体积（CTV）覆盖率平均减少 9.7%（V95）。对于传播的 DAPT 剂量，CTV 覆盖率始终得到恢复（与理想 DAPT 剂量相比，CTV V95 的平均差异<1%）。任何 DAPT 方法都会减少热点。
对于本文介绍的患者，即使每日优化基于具有一些残余不确定性的传播结构，在线 DAPT 也显示出了益处。然而，需要进行仔细的（离线）结构审查，并且可以在线下自适应中包括校正。
