Department of Radiation Oncology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
Department of Radiation Oncology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
Radiother Oncol. 2023 May;182:109575. doi: 10.1016/j.radonc.2023.109575. Epub 2023 Feb 22.
Despite the anticipated clinical benefits of intensity-modulated proton therapy (IMPT), plan robustness may be compromised due to its sensitivity to patient treatment uncertainties, especially for tumours with large motion. In this study, we investigated treatment course-wise plan robustness for intra-thoracic tumours with large motion comparing a 4D pre-clinical evaluation method (4DREM) to our clinical 3D/4D dose reconstruction and accumulation methods.
Twenty patients with large target motion (>10 mm) were treated with five times layered rescanned IMPT. The 3D-robust optimised plans were generated on the averaged planning 4DCT. Using multiple 4DCTs, treatment plan robustness was assessed on a weekly and treatment course-wise basis through the 3D robustness evaluation method (3DREM, based on averaged 4DCTs), the 4D robustness evaluation method (4DREM, including the time structure of treatment delivery and 4DCT phases) and 4D dose reconstruction and accumulation (4DREAL, based on fraction-wise information).
Baseline target motion for all patients ranged from 11-17 mm. For the offline adapted course-wise dose assessment, adequate target dose coverage was found for all patients. The target volume receiving 95% of the prescription dose was consistent between methods with 16/20 patients showing differences < 1%. 4DREAL showed the highest target coverage (99.8 ± 0.6%, p < 0.001), while no differences were observed between 3DREM and 4DREM (99.3 ± 1.3% and 99.4 ± 1.1%, respectively).
Our results show that intra-thoracic tumours can be adequately treated with IMPT in free breathing for target motion amplitudes up to 17 mm employing any of the accumulation methods. Anatomical changes, setup and range errors demonstrated a more severe impact on target coverage than motion in these patients treated with fractionated proton radiotherapy.
尽管调强质子治疗（IMPT）具有预期的临床益处，但由于其对患者治疗不确定性的敏感性，计划稳健性可能会受到影响，尤其是对于运动幅度较大的肿瘤。在这项研究中，我们比较了一种 4D 临床前评估方法（4DREM）和我们的临床 3D/4D 剂量重建和积累方法，研究了具有大运动的胸内肿瘤的治疗过程中计划稳健性。
20 名靶区运动幅度大于 10mm 的患者接受了 5 次分层重扫 IMPT 治疗。在平均计划 4DCT 上生成了 3D 稳健优化计划。使用多个 4DCT，通过 3D 稳健性评估方法（3DREM，基于平均 4DCT）、4D 稳健性评估方法（4DREM，包括治疗传递的时间结构和 4DCT 阶段）和 4D 剂量重建和积累（4DREAL，基于分次信息），每周和治疗过程中评估治疗计划的稳健性。
所有患者的基线靶区运动幅度为 11-17mm。对于离线自适应的基于疗程的剂量评估，所有患者的靶区剂量覆盖率均足够。接受处方剂量 95%的靶区体积在所有方法之间保持一致，20 名患者中有 16 名的差异<1%。4DREAL 显示出最高的靶区覆盖率（99.8±0.6%，p<0.001），而 3DREM 和 4DREM 之间没有差异（分别为 99.3±1.3%和 99.4±1.1%）。
我们的结果表明，对于运动幅度高达 17mm 的胸内肿瘤，在自由呼吸下可以用 IMPT 进行充分治疗，使用任何一种积累方法都可以。在这些接受分次质子放疗的患者中，解剖结构变化、摆位和范围误差对靶区覆盖率的影响比运动更为严重。
