Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, Texas.
Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, Texas.
Pract Radiat Oncol. 2024 Sep-Oct;14(5):e395-e406. doi: 10.1016/j.prro.2024.02.007. Epub 2024 Apr 4.
Real-time adaptation of thoracic radiation plans is compelling because offline adaptive experiences show that tumor volumes and lung anatomy can change during therapy. We present and analyze a novel adaptive-on-demand (AOD) workflow combining online adaptive radiation therapy (o-ART) on the ETHOS system with image guided radiation therapy delivery on a Halcyon unit for conventional fractionated radiation therapy of locally advanced lung cancer (LALC).
We analyzed 26 patients with LALC treated with the AOD workflow, adapting weekly. We timed segments of the workflow to evaluate efficiency in a real-world clinic. Target coverage and organ at risk (OAR) doses were compared between adaptive plans (ADP) and nonadaptive scheduled plans (SCH). Planning robustness was evaluated by the frequency of preplanning goals achieved in ADP plans, stratified by tumor volume change.
The AOD workflow was achievable within 30 minutes for most radiation fractions. Over the course of therapy, we observed an average 26.6% ± 23.3% reduction in internal target volume (ITV). Despite these changes, with o-ART, ITV and planning target volume (PTV) coverage (V100%) was 99.2% and 93.9% for all members of the cohort, respectively. This represented a 2.9% and 6.8% improvement over nonadaptive plans (P < .05), respectively. For tumors that grew >10%, V100% was 93.1% for o-ART and 76.4% for nonadaptive plans, representing a median 17.2% improvement in the PTV coverage (P < .05). In these plans, critical OAR constraints were met 94.1% of the time, whereas in nonadaptive plans, this figure was 81.9%. This represented reductions of 1.32 Gy, 1.34 Gy, or 1.75 Gy in the heart, esophagus, and lung, respectively. The effect was larger when tumors had shrunk more than 10%. Regardless of tumor volume alterations, the PTV/ITV coverage was achieved for all adaptive plans. Exceptional cases, where dose constraints were not met, were due to large initial tumor volumes or tumor growth.
The AOD workflow is efficient and robust in responding to anatomic changes in LALC patients, providing dosimetric advantages over standard therapy. Weekly adaptation was adequate to keep pace with changes. This approach is a feasible alternative to conventional offline replanning workflows for managing anatomy changes in LALC radiation therapy.
由于离线自适应经验表明，肿瘤体积和肺部解剖结构在治疗过程中会发生变化，因此实时自适应具有吸引力。我们提出并分析了一种新的自适应按需（AOD）工作流程，该流程将 ETHOS 系统上的在线自适应放射治疗（o-ART）与 Halcyon 单元上的图像引导放射治疗相结合，用于局部晚期肺癌（LALC）的常规分割放射治疗。
我们分析了 26 名接受 AOD 工作流程治疗的 LALC 患者，每周进行一次适应性治疗。我们对工作流程的各个环节进行计时，以评估在真实临床环境中的效率。在适应性计划（ADP）和非适应性计划（SCH）之间比较了靶区覆盖率和危及器官（OAR）剂量。通过在 ADP 计划中实现预计划目标的频率来评估计划的稳健性，根据肿瘤体积变化进行分层。
对于大多数放射治疗部分，AOD 工作流程可在 30 分钟内完成。在治疗过程中，我们观察到内部靶区（ITV）平均减少了 26.6%±23.3%。尽管存在这些变化，但使用 o-ART，所有患者的 ITV 和计划靶区（PTV）覆盖率（V100%）分别为 99.2%和 93.9%。这分别比非适应性计划（P<.05）提高了 2.9%和 6.8%。对于生长>10%的肿瘤，o-ART 的 V100%为 93.1%，非适应性计划为 76.4%，这代表 PTV 覆盖率中位数提高了 17.2%（P<.05）。在这些计划中，关键 OAR 约束得到了 94.1%的满足，而非适应性计划中这一比例为 81.9%。这分别代表心脏、食管和肺部的剂量减少了 1.32 Gy、1.34 Gy 和 1.75 Gy。当肿瘤缩小超过 10%时，效果更大。无论肿瘤体积变化如何，所有适应性计划都实现了 PTV/ITV 覆盖率。剂量限制未得到满足的特殊情况是由于初始肿瘤体积较大或肿瘤生长所致。
AOD 工作流程在响应 LALC 患者的解剖变化方面效率高且稳健，与标准治疗相比具有剂量优势。每周的适应性治疗足以跟上变化的步伐。对于管理局部晚期肺癌放射治疗中的解剖变化，这种方法是传统离线重新计划工作流程的一种可行替代方案。
