Varian Medical Systems Inc, Palo Alto, CA; Medical College of Wisconsin, Department of Radiation Oncology, Wauwatosa, WI.
Varian Medical Systems Inc, Palo Alto, CA.
Med Dosim. 2022;47(3):258-263. doi: 10.1016/j.meddos.2022.04.003. Epub 2022 May 3.
Whole-brain radiotherapy has been the standard palliative treatment for patients with brain metastases due to its effectiveness, availability, and ease of administration. Recent clinical trials have shown that limiting radiation dose to the hippocampus is associated with decreased cognitive toxicity. In this study, we updated an existing Knowledge Based Planning model to further reduce dose to the hippocampus and improve other dosimetric plan quality characteristics. Forty-two clinical cases were contoured according to guidelines. A new dosimetric scorecard was created as an objective measure for plan quality. The new Hippocampal Sparing Whole Brain Version 2 (HSWBv2) model adopted a complex recursive training process and was validated with five additional cases. HSWBv2 treatment plans were generated on the Varian Halcyon and TrueBeam systems and compared against plans generated from the existing (HSWBv1) model released in 2016. On the Halcyon platform, 42 cases were re-planned. Hippocampal D from HSWBv2 and HSWBv1 models had an average dose of 5.75 Gy and 6.46 Gy, respectively (p < 0.001). HSWBv2 model also achieved a hippocampal D of 7.49 Gy, vs 8.10 Gy in HSWBv1 model (p < 0.001). Hippocampal D from HSWBv2 model was 9.86 Gy, in contrast to 10.57 Gy in HSWBv1 (p < 0.001). For PTV_3000, D and D from HSWBv2 model were 28.27 Gy and 31.81 Gy, respectively, compared to 28.08 Gy (p = 0.020) and 32.66 Gy from HSWBv1 (p < 0.001). Among several other dosimetric quality improvements, there was a significant reduction in PTV_3000 V from 35.35% (HSWBv1) to 6.44% (HSWBv2) (p < 0.001). On 5 additional validation cases, dosimetric improvements were also observed on TrueBeam. In comparison to published data, the HSWBv2 model achieved higher quality hippocampal avoidance whole brain radiation therapy treatment plans through further reductions in hippocampal dose while improving target coverage and dose conformity/homogeneity. HSWBv2 model is shared publicly.
全脑放疗一直是脑转移患者的标准姑息治疗方法，因为它具有疗效好、可获得性高和易于管理的特点。最近的临床试验表明，将辐射剂量限制在海马体可降低认知毒性。在这项研究中，我们更新了现有的基于知识的计划模型，以进一步降低海马体的剂量，并改善其他剂量学计划质量特征。根据指南对 42 例临床病例进行了轮廓描绘。创建了一个新的剂量学记分卡作为计划质量的客观衡量标准。新的海马体保护全脑版本 2 (HSWBv2) 模型采用了复杂的递归训练过程，并通过另外 5 例验证。HSWBv2 治疗计划在瓦里安 Halcyon 和 TrueBeam 系统上生成，并与 2016 年发布的现有（HSWBv1）模型生成的计划进行比较。在 Halcyon 平台上，对 42 例病例进行了重新规划。HSWBv2 和 HSWBv1 模型的海马体 D 平均剂量分别为 5.75Gy 和 6.46Gy（p<0.001）。HSWBv2 模型还实现了 7.49Gy 的海马体 D，而 HSWBv1 模型为 8.10Gy（p<0.001）。HSWBv2 模型的海马体 D 为 9.86Gy，而 HSWBv1 模型为 10.57Gy（p<0.001）。对于 PTV_3000，HSWBv2 模型的 D 和 D 分别为 28.27Gy 和 31.81Gy，而 HSWBv1 模型分别为 28.08Gy（p=0.020）和 32.66Gy（p<0.001）。在其他几个剂量学质量改进方面，PTV_3000 V 从 35.35%（HSWBv1）显著降低到 6.44%（HSWBv2）（p<0.001）。在另外 5 个验证病例中，在 TrueBeam 上也观察到了剂量学的改善。与已发表的数据相比，HSWBv2 模型通过进一步降低海马体剂量，同时提高靶区覆盖和剂量一致性/均匀性，实现了更高质量的海马体回避全脑放射治疗计划。HSWBv2 模型是公开共享的。
