Abstract：
OBJECTIVE: 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.
METHODS: 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 PTVall, and the brain region excluding PTVall 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 (V5Gy, V12Gy, and V18Gy, respectively) were used for evaluation of normal brain dose. Correlations between normal brain dose and each tumor characteristic (number, PTVall, and TSA) were investigated using the Spearman rank correlation coefficient.
RESULTS: Correlations between each characteristic and normal brain dose were statistically significant (p < 0.05) across all machines. The correlation coefficients between each characteristic and V18Gy for the five machines were as follows: tumor number, 0.39-0.60; PTVall, 0.79-0.93; TSA, 0.93-0.99. The fit equations between TSA and V18Gy exhibited high coefficients of determination, ranging from 0.92 to 0.99 across five machines.
CONCLUSIONS: 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.
METHODS: 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 PTVall, and the brain region excluding PTVall 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 (V5Gy, V12Gy, and V18Gy, respectively) were used for evaluation of normal brain dose. Correlations between normal brain dose and each tumor characteristic (number, PTVall, and TSA) were investigated using the Spearman rank correlation coefficient.
RESULTS: Correlations between each characteristic and normal brain dose were statistically significant (p < 0.05) across all machines. The correlation coefficients between each characteristic and V18Gy for the five machines were as follows: tumor number, 0.39-0.60; PTVall, 0.79-0.93; TSA, 0.93-0.99. The fit equations between TSA and V18Gy exhibited high coefficients of determination, ranging from 0.92 to 0.99 across five machines.
CONCLUSIONS: 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.
摘要：
目的：本研究旨在寻找与正常脑剂量相关的描述符，以确定使用五台直线加速器机器对多发性脑转移瘤（BMs）进行分割立体定向放射外科（SRS）的可行性。
方法：纳入32例1-30例BMs患者。使用TrueBeam创建治疗计划，诺瓦利斯Tx,TrueBeam边缘,Halcyon,和Tomotherapy直线加速器。所有计划目标体积(PTV)的总和定义为PTVall，不包括PTVall的大脑区域被定义为正常大脑。PTV的总表面积(TSA)由每个PTV的等效球体的表面积的总和计算。接收超过5、12和18Gy(V5Gy,V12Gy,和V18Gy,分别）用于评估正常的脑剂量。正常脑剂量与每个肿瘤特征之间的相关性(数量，PTVall,和TSA）使用Spearman秩相关系数进行调查。
结果：在所有机器中，每个特征与正常脑剂量之间的相关性均具有统计学意义（p<0.05）。五个机器的每个特征与V18Gy之间的相关系数如下：肿瘤数，0.39-0.60;PTVall,0.79-0.93;TSA,0.93-0.99。TSA和V18Gy之间的拟合方程表现出很高的确定系数，五台机器的范围从0.92到0.99。
结论：这项研究设计了使用5台直线加速器机器的1-30个BMs的分段SRS计划，以找到基于正常脑剂量确定SRS可行性的描述符。TSA被证明是用于治疗多个BM的SRS可行性的有希望的描述符。
方法：纳入32例1-30例BMs患者。使用TrueBeam创建治疗计划，诺瓦利斯Tx,TrueBeam边缘,Halcyon,和Tomotherapy直线加速器。所有计划目标体积(PTV)的总和定义为PTVall，不包括PTVall的大脑区域被定义为正常大脑。PTV的总表面积(TSA)由每个PTV的等效球体的表面积的总和计算。接收超过5、12和18Gy(V5Gy,V12Gy,和V18Gy,分别）用于评估正常的脑剂量。正常脑剂量与每个肿瘤特征之间的相关性(数量，PTVall,和TSA）使用Spearman秩相关系数进行调查。
结果：在所有机器中，每个特征与正常脑剂量之间的相关性均具有统计学意义（p<0.05）。五个机器的每个特征与V18Gy之间的相关系数如下：肿瘤数，0.39-0.60;PTVall,0.79-0.93;TSA,0.93-0.99。TSA和V18Gy之间的拟合方程表现出很高的确定系数，五台机器的范围从0.92到0.99。
结论：这项研究设计了使用5台直线加速器机器的1-30个BMs的分段SRS计划，以找到基于正常脑剂量确定SRS可行性的描述符。TSA被证明是用于治疗多个BM的SRS可行性的有希望的描述符。
