Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan; Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan.
Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan.
Med Dosim. 2023;48(2):67-72. doi: 10.1016/j.meddos.2022.12.001. Epub 2023 Jan 16.
To compare dosimetric parameters for the hippocampus, organs at risk (OARs), and targets of volumetric modulated arc therapy (VMAT), noncoplanar VMAT (NC-VMAT), and HyperArc (HA) plans in patients undergoing postoperative radiotherapy for primary brain tumors. For 20 patients, HA plans were generated to deliver 40.05 to 60 Gy for the planning target volume (PTV). In addition, doses for the hippocampus and OARs were minimized. The VMAT and NC-VMAT plans were retrospectively generated using the same optimization parameters as those in the HA plans. For the hippocampus, the equivalent dose to be administered in 2 Gy fractions (EQD) was calculated assuming α/β = 2. Dosimetric parameters for the PTV, hippocampus, and OARs in the VMAT, NC-VMAT, and HA plans were compared. For PTV, the HA plans provided significantly lower D and D than the VMAT and NC-VMAT plans (p < 0.05), whereas the D and D were significantly higher (p < 0.05). For the contralateral hippocampus, the dosimetric parameters in the HA plans (8.1 ± 9.6, 6.5 ± 7.2, 5.6 ± 5.8, and 4.8 ± 4.7 Gy for D, D, D and D, respectively) were significantly smaller (p < 0.05) than those in the VMAT and NC-VMAT plans. Except for the optic chiasm, the D in the HA plans (brainstem, lens, optic nerves, and retinas) was the smallest (p < 0.05). In addition, the doses in the HA plans for the brain and skin were the smallest (p < 0.05) among the 3 plans. HA planning, instead of coplanar and noncoplanar VMAT, significantly reduces the dosage to which the contralateral hippocampus as well as other OARs are exposed without compromising on target coverage.
比较原发性脑肿瘤术后放疗患者的 hippocampus、器官危及器官 (OARs) 和容积调强弧形治疗 (VMAT)、非共面 VMAT (NC-VMAT) 和 HyperArc (HA) 计划的剂量学参数。为 20 名患者生成 HA 计划，以对计划靶区 (PTV) 给予 40.05 至 60 Gy。此外，还最小化了 hippocampus 和 OAR 的剂量。使用与 HA 计划相同的优化参数，回顾性生成了 VMAT 和 NC-VMAT 计划。对于 hippocampus，假设 α/β = 2，计算以 2 Gy 分数给予的等效剂量 (EQD)。比较 VMAT、NC-VMAT 和 HA 计划的 PTV、hippocampus 和 OAR 的剂量学参数。对于 PTV，HA 计划提供的 D 和 D 明显低于 VMAT 和 NC-VMAT 计划 (p < 0.05)，而 D 和 D 明显更高 (p < 0.05)。对于对侧 hippocampus，HA 计划中的剂量学参数 (D、D、D 和 D 分别为 8.1 ± 9.6、6.5 ± 7.2、5.6 ± 5.8 和 4.8 ± 4.7 Gy) 明显更小 (p < 0.05) VMAT 和 NC-VMAT 计划。除了视交叉外，HA 计划中的 D (脑干、晶状体、视神经和视网膜) 最小 (p < 0.05)。此外，HA 计划中的脑和皮肤剂量在 3 个计划中最小 (p < 0.05)。与共面和非共面 VMAT 相比，HA 计划可显著降低对侧 hippocampus 以及其他 OAR 暴露的剂量，同时不影响靶区覆盖。
