Department of Radiation Oncology, McGill University Health Centre, Montreal, QC, Canada.
J Appl Clin Med Phys. 2012 Jul 5;13(4):3826. doi: 10.1120/jacmp.v13i4.3826.
The purpose of this study was to compare dosimetric and radiobiological parameters of treatment plans using coplanar and noncoplanar beam arrangements in patients with fronto-temporal high-grade glioma (HGG) generated for intensity-modulated radiotherapy (IMRT) or volumetric-modulated arc therapy (VMAT). Ten cases of HGG overlapping the optic apparatus were selected. Four separate plans were created for each case: coplanar IMRT, noncoplanar IMRT (ncIMRT), VMAT, and noncoplanar VMAT (ncVMAT). The prescription dose was 60 Gy in 30 fractions. Dose-volume histograms and equivalent uniform doses (EUD) for planning target volumes (PTVs) and organs at risk (OARs) were generated. The four techniques resulted in comparable mean, minimum, maximum PTV doses, and PTV EUDs (p ≥ 0.33). The mean PTV dose and EUD averaged for all techniques were 59.98 Gy (Standard Deviation (SD) ± 0.15) and 59.86 Gy (SD ± 0.27). Non-coplanar IMRT significantly reduced contralateral anterior globe EUDs (6.7 Gy versus 8.2 Gy, p = 0.05), while both ncIMRT and ncVMAT reduced contralateral retina EUDs (16 Gy versus 18.8 Gy, p = 0.03). Noncoplanar techniques resulted in lower contralateral temporal lobe dose (22.2 Gy versus 24.7 Gy). Compared to IMRT, VMAT techniques required fewer monitor units (755 vs. 478, p ≤ 0.001) but longer optimization times. Treatment delivery times were 6.1 and 10.5 minutes for coplanar and ncIMRT versus 2.9 and 5.0 minutes for coplanar and ncVMAT. In this study, all techniques achieved comparable target coverage. Superior sparing of contralateral optic structures was seen with ncIMRT. The VMAT techniques reduced treatment delivery duration but prolonged plan optimization times, compared to IMRT techniques. Technique selection should be individualized, based on patient-specific clinical and dosimetric parameters.
本研究旨在比较适形和非适形布野在生成调强放疗(IMRT)或容积旋转调强放疗(VMAT)计划中治疗前颅底-颞叶高级别胶质瘤(HGG)患者的剂量学和放射生物学参数。选择了 10 例重叠视器的 HGG 病例。为每个病例分别创建了 4 个计划:适形 IMRT、非适形 IMRT(ncIMRT)、VMAT 和非适形 VMAT(ncVMAT)。处方剂量为 60 Gy,分 30 次。生成了计划靶区(PTV)和危及器官(OAR)的剂量-体积直方图和等效均匀剂量(EUD)。四种技术的平均、最小、最大 PTV 剂量和 PTV EUD 相似(p≥0.33)。所有技术的平均 PTV 剂量和 EUD 平均值为 59.98 Gy(标准差(SD)±0.15)和 59.86 Gy(SD±0.27)。非适形 IMRT 显著降低了对侧前球 EUD(6.7 Gy 对 8.2 Gy,p=0.05),而 ncIMRT 和 ncVMAT 均降低了对侧视网膜 EUD(16 Gy 对 18.8 Gy,p=0.03)。非适形技术导致较低的对侧颞叶剂量(22.2 Gy 对 24.7 Gy)。与 IMRT 相比,VMAT 技术需要更少的监控单位(755 对 478,p≤0.001),但优化时间更长。共面和非共面 ncIMRT 的治疗时间分别为 6.1 和 10.5 分钟,而共面和非共面 ncVMAT 的治疗时间分别为 2.9 和 5.0 分钟。在本研究中,所有技术均达到了可比的靶区覆盖。ncIMRT 对同侧视神经结构的保护更好。与 IMRT 技术相比,VMAT 技术缩短了治疗时间,但延长了计划优化时间。技术选择应根据患者的具体临床和剂量学参数个体化。