Duan Yanhua, Lin Yang, Wang Hao, Kang Bodong, Feng Aihui, Ma Kui, Chen Hua, Huang Ying, Gu Hengle, Shao Yan, Zhou Tao, Kong Qing, Xu Zhiyong
Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China.
Pekoe Team, MIM Software Inc., Cleveland, OH, United States.
Front Oncol. 2021 Nov 15;11:781302. doi: 10.3389/fonc.2021.781302. eCollection 2021.
Gradient measure (GM) is a critical index related to normal tissue sparing in radiosurgery. This study aims to describe the dependence of GM on target volume and target shape for lung stereotactic body radiation therapy (SBRT) treatment plans.
A total of 307 peripheral and 119 central lung SBRT treatment plans were enrolled for this study. A least-squares regression was used for data analysis. First, the equations with different functional forms were established to determine the dependence of GM on a univariaty (V or Sp) and bivariaty (V and Sp), respectively. Then, the correlation coefficients and p-values of variables for all equations were compared and analyzed to determine the dependence of GM on PTV volume (VP) and sphericity (Sp).
The power equations had the highest coefficient of determination (R) in the dependence results of GM on univariate V. The equations were and for peripheral and central lesions, respectively. On the other hand, the R of all functional forms were less than 0.25 when the relationship of GM versus univariate Sp was analyzed. Similarly, the power equation also obtained the highest R in bivariaty V and Sp analysis, whether for central or peripheral. However, the R of the bivariate equations were not improved compared with those of univariate equations. Moreover, the p-values of the variable Sp were greater than 0.05.
The GM of the lung SBRT plan is shape-independent and volume-dependent. The dependence of GM on PTV volume for peripheral and central lung cancer can be described by two different power equations. The results of this study can be used as a potential tool to assist dosimetric quality control during the radiosurgery process.
梯度测量（GM）是放射外科中与正常组织保护相关的关键指标。本研究旨在描述肺立体定向体部放疗（SBRT）治疗计划中GM对靶区体积和靶区形状的依赖性。
本研究共纳入307例周围型和119例中央型肺SBRT治疗计划。采用最小二乘法回归进行数据分析。首先，建立具有不同函数形式的方程，分别确定GM对单变量（V或Sp）和双变量（V和Sp）的依赖性。然后，比较并分析所有方程变量的相关系数和p值，以确定GM对计划靶区体积（VP）和球形度（Sp）的依赖性。
在GM对单变量V的依赖性结果中，幂方程的决定系数（R）最高。对于周围型和中央型病变，方程分别为 和 。另一方面，在分析GM与单变量Sp的关系时，所有函数形式的R均小于0.25。同样，无论是中央型还是周围型，在双变量V和Sp分析中幂方程也获得了最高的R。然而，双变量方程的R与单变量方程相比没有提高。此外，变量Sp的p值大于0.05。
肺SBRT计划的GM与形状无关，与体积有关。周围型和中央型肺癌GM对PTV体积的依赖性可用两个不同的幂方程描述。本研究结果可作为放射外科过程中辅助剂量质量控制的潜在工具。
