Complexity score‐based plan quality control of VMAT
Hu Jinyan1, Zhang Liyuan2, Ma Yangguang1, Han Bin1, Guo Yuexin1
1Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China; 2Department of Radiation Oncology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou 450007, China
Abstract：Objective To explore the difference in the complexity of different treatment planning systems, multi‐leaf collimator (MLC) types and treatment sites of volume‐modulated arc therapy (VMAT), and propose a complexity score for plan quality control. Methods Statistical analysis of 12 complexity metrics including Monaco and Eclipse, Agility, Millennium and High‐definition MLC, nasopharyngeal, lung and cervical cancer was performed. Spearman correlation coefficient between complexity metrics was calculated. Principal component analysis was conducted to reduce the dimensionality of the original data set to the first two principal components and explain its physical meaning. Complexity score based on the principal components was calculated to establish warning and action thresholds for plan quality control. The correlation between complexity metrics and γ pass rate was analyzed. Results Except cervical cancer aperture sub‐regions metric, other metrics had significant differences between Monaco and Eclipse. Monaco MLC had a more regular field but higher MU, smaller leaf gap, and longer leaf travel distance. High‐definition MLC with smaller leaf width significantly added MLC aperture‐related metrics. The first two principal components explained over 80% of the total variance of the original dataset, complexity score was weighted average of first two principal components. The distribution of complexity score for different equipment and sites was different. The warning threshold was expressed as the average plus standard deviation, and the action threshold was expressed as the average plus 2 standard deviations. Complexity metrics and complexity scores had small correlation with γ pass rate, showing weak or irrelevant but statistically significant. Conclusions Different planning systems, MLC types, and treatment site complexity metrics are significantly different. The complexity score is a useful tool for plan quality control.
Hu Jinyan,Zhang Liyuan,Ma Yangguang et al. Complexity score‐based plan quality control of VMAT[J]. Chinese Journal of Radiation Oncology, 2022, 31(9): 817-822.
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