Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osakasayama, Osaka, Japan.
Department of Radiotherapy, Takarazuka City Hospital, Takarazuka, Hyogo, Japan.
J Appl Clin Med Phys. 2024 Sep;25(9):e14413. doi: 10.1002/acm2.14413. Epub 2024 Jun 24.
This study aimed to find descriptors that correlates with normal brain dose to determine the feasibility of performing fractionated stereotactic radiosurgery (SRS) for multiple brain metastases (BMs) using five linac machines.
Thirty-two patients with 1-30 BMs were enrolled. Treatment plans were created using TrueBeam, Novalis Tx, TrueBeam Edge, Halcyon, and Tomotherapy linacs. The sum of all planning target volumes (PTVs) was defined as PTV, and the brain region excluding PTV was defined as normal brain. The total surface area (TSA) of the PTV was calculated from the sum of the surface areas of the equivalent spheres for each PTV. Volumes receiving more than 5, 12, and 18 Gy (V, V, and V, respectively) were used for evaluation of normal brain dose. Correlations between normal brain dose and each tumor characteristic (number, PTV, and TSA) were investigated using the Spearman rank correlation coefficient.
Correlations between each characteristic and normal brain dose were statistically significant (p < 0.05) across all machines. The correlation coefficients between each characteristic and V for the five machines were as follows: tumor number, 0.39-0.60; PTV, 0.79-0.93; TSA, 0.93-0.99. The fit equations between TSA and V exhibited high coefficients of determination, ranging from 0.92 to 0.99 across five machines.
This study devised fractionated SRS plans using for 1-30 BMs across five linac machines to find descriptors for determining SRS feasibility based on normal brain dose. TSA proved to be a promising descriptor of SRS feasibility for treating multiple BMs.
本研究旨在寻找与正常脑剂量相关的指标，以确定使用五台直线加速器为多个脑转移瘤（BM）实施分次立体定向放射外科治疗（SRS）的可行性。
共纳入 32 例 1-30 个 BM 的患者。使用 TrueBeam、Novalis Tx、TrueBeam Edge、Halcyon 和 Tomotherapy 直线加速器制定治疗计划。所有计划靶区（PTV）的总和定义为 PTV，而 PTV 以外的脑区定义为正常脑。从每个 PTV 的等效球体表面积之和计算 PTV 的总表面积（TSA）。用于评估正常脑剂量的体积分别为 5、12 和 18 Gy（V、V 和 V）以上的体积。使用 Spearman 秩相关系数研究正常脑剂量与每个肿瘤特征（数量、PTV 和 TSA）之间的相关性。
所有机器中，正常脑剂量与每个特征之间的相关性均具有统计学意义（p<0.05）。五个机器中每个特征与 V 的相关系数如下：肿瘤数量，0.39-0.60；PTV，0.79-0.93；TSA，0.93-0.99。TSA 与 V 之间的拟合方程具有较高的决定系数，在五个机器中范围为 0.92 至 0.99。
本研究设计了使用五台直线加速器为 1-30 个 BM 进行分次 SRS 计划，以寻找基于正常脑剂量确定 SRS 可行性的指标。TSA 被证明是评估多灶性 BM 立体定向放射外科治疗可行性的一个有前途的指标。
