Shandong University, Jinan, 250117, Shandong, China.
Department of Radiation Oncology, Shandong Cancer Hospital affiliated to Shandong University, 440 Jiyan Road, Jinan, 250117, Shandong, China.
Radiat Oncol. 2019 Mar 15;14(1):46. doi: 10.1186/s13014-019-1255-7.
To perform a dosimetric evaluation of four different simultaneous integrated boost whole brain radiotherapy modalities with hippocampus and inner ear avoidance in the treatment of limited brain metastases.
Computed tomography/magnetic resonance imaging data of 10 patients with limited (1-5) brain metastases were used to replan step-and-shoot intensity-modulated radiotherapy (sIMRT), dynamic intensity-modulated radiation therapy (dIMRT), volumetric-modulated arc therapy (VMAT), and helical tomotherapy (Tomo). The prescribed doses of 40-50 Gy in 10 fractions and 30 Gy in 10 fractions were simultaneously delivered to the metastatic lesions and the whole-brain volume, respectively. The hippocampal dose met the RTOG 0933 criteria for hippocampal avoidance (Dmax ≤17 Gy, D100% ≤10 Gy). The inner ear dose was restrained to Dmean ≤15 Gy. Target coverage (TC), homogeneity index (HI), conformity index (CI), maximum dose (Dmax), minimum dose (Dmin) and dose to organs at risk (OARs) were compared.
All plans met the indicated dose restrictions. The mean percentage of planning target volume of metastases (PTVmets) coverage ranged from 97.1 to 99.4%. For planning target volume of brain (PTVbrain), Tomo provided the lowest average D2% (37.5 ± 2.8 Gy), the highest average D98% (25.2 ± 2.0 Gy), and the best TC (92.6% ± 2.1%) and CI (0.79 ± 0.06). The two fixed gantry IMRT modalities (step and shot, dynamic) provided similar PTVbrain dose homogeneity (both 0.76). Significant differences across the four approaches were observed for the maximum and minimum doses to the hippocampus and the maximum doses to the eyes, lens and optic nerves.
All four radiotherapy modalities produced acceptable treatment plans with good avoidance of the hippocampus and inner ear. Tomo obtained satisfactory PTVbrain coverage and the best homogeneity index.
Clinicaltrials.gov, NCT03414944 . Registered 29 January 2018.
在治疗局限性脑转移瘤时，对 4 种不同的同时整合海马和内耳回避的全脑放疗模式进行剂量学评估。
利用 10 例局限性（1-5 个）脑转移瘤患者的计算机断层扫描/磁共振成像数据，重新规划步进式强度调制放疗（sIMRT）、动态强度调制放疗（dIMRT）、容积调强弧形治疗（VMAT）和螺旋断层放疗（Tomo）。40-50Gy 分 10 次和 30Gy 分 10 次同时给予转移病灶和全脑体积。海马剂量符合 RTOG 0933 海马回避标准（Dmax≤17Gy，D100%≤10Gy）。内耳剂量限制在 Dmean≤15Gy。比较了靶区覆盖率（TC）、均匀性指数（HI）、适形指数（CI）、最大剂量（Dmax）、最小剂量（Dmin）和危及器官（OARs）剂量。
所有计划均符合规定的剂量限制。转移灶计划靶区（PTVmets）覆盖率的平均值为 97.1%-99.4%。对于脑计划靶区（PTVbrain），Tomo 提供了最低的平均 D2%（37.5±2.8Gy），最高的平均 D98%（25.2±2.0Gy），以及最佳的 TC（92.6%±2.1%）和 CI（0.79±0.06）。两个固定机架的调强放疗模式（步进和动态）提供了相似的 PTVbrain 剂量均匀性（均为 0.76）。4 种方法之间在海马和眼睛、晶状体和视神经的最大和最小剂量方面存在显著差异。
所有 4 种放疗方式均能产生可接受的治疗计划，对海马和内耳有良好的回避作用。Tomo 获得了满意的 PTVbrain 覆盖率和最佳的均匀性指数。
Clinicaltrials.gov，NCT03414944。于 2018 年 1 月 29 日注册。
