Aims

To carry out a dosimetric comparison and constraints feasibility proof of adjuvant radiotherapy through helical tomotherapy or volumetric modulated arc therapy (VMAT) for malignant pleural mesothelioma patients after pleurectomy/decortication.

Materials and methods

Retrospective calculations were carried out on previously acquired simulations. A whole-pleura volume with 50.4 Gy in 28 fractions was prescribed, simulating a no residual tumour situation. Calculations were carried out using an anisotropic analytical algorithm with a 2.0 mm grid. Beam-on time, planning target volume (PTV) coverage, homogeneity index and organ at risk exposure were compared.

Results

Sixteen patient plans were calculated per device. Constraints were met overall by both modalities. For helical tomotherapy and VMAT plans, median beam-on times were 13.8 (11.6–16.1) min and 6.4 (6.1–7.0) min; P = 0.006. The median left-sided radiotherapy PTV D₉₈ were 48.1 (48.0–48.8) Gy and 47.6 (46.5–48.3) Gy; P = 0.023. No significant difference for right-sided radiotherapy was found. PTV D₂ for left-sided radiotherapy was higher with VMAT (P = 0.014). For right-sided radiotherapy, helical tomotherapy showed higher doses (P = 0.039). No homogeneity index differences for left-sided radiotherapy (P = 1.00) and right-sided radiotherapy (P = 0.598) were seen. Significant organ at risk exposure differences were found on left-sided radiotherapy whole-lung V_20, as well as D₅₀ (both P = 0.008). Higher contralateral lung and ipsilateral kidney exposures were found with VMAT plans for both treatment sides.

Conclusion

Adjuvant radiotherapy after pleurectomy/decortication in malignant pleural mesothelioma patients, with a VMAT- or helical tomotherapy-based platform, is dosimetrically feasible. Lung sparing was mostly improved with helical tomotherapy. Technique selection must be carried out according to availability and clinical criteria.

中文翻译：

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恶性胸膜间皮瘤患者螺旋断层放疗与容积调节弧治疗的剂量学比较

目标

对恶性胸膜间皮瘤患者胸膜切除/剥脱术后通过螺旋断层放疗或容积调制弧治疗（VMAT）进行辅助放疗的剂量学比较和约束可行性证明。

材料和方法

对先前获得的模拟进行了回顾性计算。规定了 28 个部分 50.4 Gy 的全胸膜体积，模拟无残留肿瘤的情况。使用具有 2.0 mm 网格的各向异性分析算法进行计算。比较了光束开启时间、计划目标体积 (PTV) 覆盖率、同质性指数和器官暴露风险。

结果

每个设备计算了 16 名患者计划。两种方式总体上都满足了限制条件。对于螺旋断层治疗和 VMAT 计划，中位光束开启时间为 13.8 (11.6-16.1) 分钟和 6.4 (6.1-7.0) 分钟；P = 0.006。中位左侧放疗 PTV D ₉₈分别为 48.1 (48.0–48.8) Gy 和 47.6 (46.5–48.3) Gy；P = 0.023。右侧放疗未发现显着差异。VMAT 左侧放疗的PTV D _2更高（ P = 0.014）。对于右侧放疗，螺旋断层放疗显示出更高的剂量（P = 0.039）。左侧放疗（P = 1.00）和右侧放疗（P= 0.598)。在左侧放疗全肺 V ₂₀和 D ₅₀上发现了显着的风险器官暴露差异（均P = 0.008）。治疗两侧的 VMAT 计划发现更高的对侧肺和同侧肾脏暴露。

结论

恶性胸膜间皮瘤患者胸膜切除术/去皮质后的辅助放射治疗，使用基于 VMAT 或螺旋断层治疗的平台，在剂量学上是可行的。螺旋断层放疗主要改善了肺保留。技术选择必须根据可用性和临床标准进行。