Department of Radiation Medicine, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
J Appl Clin Med Phys. 2012 Sep 1;14(1):4110. doi: 10.1120/jacmp.v14i1.4110.
The purpose of this study was to demonstrate the dosimetric potential of volumetric-modulated arc therapy (VMAT) for the treatment of patients with medically inoperable stage I/II non-small cell lung cancer (NSCLC) with stereotactic body radiation therapy (SBRT). Fourteen patients treated with 3D CRT with varying tumor locations, tumor sizes, and dose fractionation schemes were chosen for study. The prescription doses were 48 Gy in 4 fractions, 52.5 Gy in 5 fractions, 57.5 Gy in 5 fractions, and 60 Gy in 3 fractions for 2, 5, 1, and 6 patients, respectively. VMAT treatment plans with a mix of two to three full and partial noncoplanar arcs with 5°-25° separations were retrospectively generated using Eclipse version 10.0. The 3D CRT and VMAT plans were then evaluated by comparing their target dose, critical structure dose, high dose spillage, and low dose spillage as defined according to RTOG 0813 and RTOG 0236 protocols. In the most dosimetrically improved case, VMAT was able to decrease the dose from 17.35 Gy to 1.54 Gy to the heart. The D(2cm) decreased in 11 of 14 cases when using VMAT. The three that worsened were still within the acceptance criteria. Of the 14 3D CRT plans, seven had a D(2cm) minor deviation, while only one of the 14 VMAT plans had a D(2cm) minor deviation. The R(50%) improved in 13 of the 14 VMAT cases. The one case that worsened was still within the acceptance criteria of the RTOG protocol. Of the 14 3D CRT plans, seven had an R(50%) deviation. Only one of the 14 VMAT plans had an R(50%) deviation, but it was still improved compared to the 3D CRT plan. In this cohort of patients, no evident dosimetric compromises resulted from planning SBRT treatments with VMAT relative to the 3D CRT treatment plans actually used in their treatment.
本研究旨在展示容积调强弧形治疗（VMAT）在治疗不能手术的 I/II 期非小细胞肺癌（NSCLC）患者中的剂量学潜力，这些患者采用立体定向体部放射治疗（SBRT）进行治疗。选择了 14 名接受 3D-CRT 治疗的患者进行研究，这些患者的肿瘤位置、肿瘤大小和剂量分割方案各不相同。处方剂量分别为 48 Gy 分 4 次、52.5 Gy 分 5 次、57.5 Gy 分 5 次和 60 Gy 分 3 次，分别用于 2、5、1 和 6 名患者。使用 Eclipse 版本 10.0 回顾性生成了混合两个到三个全弧和部分非共面弧的 VMAT 治疗计划，这些弧的夹角为 5°-25°。根据 RTOG 0813 和 RTOG 0236 协议，比较了 3D-CRT 和 VMAT 计划的靶区剂量、关键结构剂量、高剂量外溢和低剂量外溢，对这两种计划进行了评估。在剂量学改善最明显的情况下，VMAT 能够将心脏的剂量从 17.35 Gy 降低到 1.54 Gy。在 14 个病例中有 11 个病例的 D（2cm）降低。虽然恶化的病例仍在可接受的范围内。在 14 个 3D-CRT 计划中，有 7 个计划的 D（2cm）有轻微偏差，而在 14 个 VMAT 计划中，只有 1 个计划的 D（2cm）有轻微偏差。在 14 个 VMAT 病例中有 13 个病例的 R（50%）得到改善。虽然有 1 个病例的 R（50%）恶化，但仍在 RTOG 方案的可接受范围内。在 14 个 3D-CRT 计划中，有 7 个计划的 R（50%）有偏差。在 14 个 VMAT 计划中，只有 1 个计划的 R（50%）有偏差，但与 3D-CRT 计划相比，它仍有改善。在本患者队列中，与实际用于治疗的 3D-CRT 治疗计划相比，使用 VMAT 计划进行 SBRT 治疗并未导致明显的剂量学缺陷。
