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Abstract：
Patient quality assurance (QA) is a required part of the treatment care path, and plan failure can lead to increased personnel hours or delay of treatment. The recommendation by the American Association of Physicists in Medicine is that gamma analysis be used to evaluate measured volumetric modulated arc therapy plans. Vendors have developed many different measurement geometries for patient QA devices which could yield varying pass rates when used with the recommended tolerances, normalization, and criterion. For this study, clinically treated stereotactic body radiation therapy plans were used to evaluate differences in gamma dose tolerances and sampled dose distribution complexity for centralized or peripheral measurement geometries on a cylindrical phantom. Random errors were then introduced into a subset of these plans, and the differences in pass rates between the geometries were correlated with differences in the observed mathematical differences. Finally, a single clinically relevant target coverage deviation was introduced to another subset of plans to evaluate whether a particular geometry is measurably better at identifying clinically relevant errors. It was found that centralized geometries resulted in more lenient dose tolerances and less complex sampled dose distributions compared to peripheral geometries. Pass rates were uniformly lower in the peripheral measurement geometry, and the difference in pass rates between the geometries correlated strongly with the difference in dose tolerance and weakly with the difference in the chosen complexity metrics. However, neither of the geometries were sufficiently sensitive enough to detect clinically relevant changes to target coverage when using recommended tolerances and criteria, and no statistically significant difference was found between their pass rates. Given these findings, the authors concluded that stereotactic body radiation therapy plans could fail patient QA when measured in the peripheral geometry but pass in the centralized geometry, with possibly neither having correlation to true clinical deviation.
摘要：
患者质量保证（QA）是治疗护理路径的必要部分，计划失败会导致人员工作时间增加或延误治疗。美国医学物理学家协会的建议是使用伽马分析来评估测量的体积调制电弧治疗计划。供应商已经为患者QA设备开发了许多不同的测量几何形状，当使用推荐的公差时，可以产生不同的合格率。归一化，和标准。对于这项研究，临床治疗的立体定向身体放射治疗计划用于评估圆柱形体模上的集中式或外围测量几何结构的γ剂量容限和采样剂量分布复杂性的差异.然后将随机误差引入这些计划的子集，几何形状之间的通过率差异与观察到的数学差异相关。最后,将单一临床相关目标覆盖偏差引入另一个计划子集,以评估特定几何结构在识别临床相关错误方面是否具有可测量的更好效果.发现与外围几何形状相比，集中式几何形状导致更宽松的剂量公差和更不复杂的采样剂量分布。周边测量几何形状的合格率均匀较低，几何形状之间的通过率差异与剂量耐受性的差异密切相关，而与所选择的复杂性指标的差异密切相关。然而,当使用推荐的公差和标准时，两种几何形状都没有足够的灵敏度来检测目标覆盖范围的临床相关变化。他们的通过率之间没有统计学上的显着差异。鉴于这些发现,作者得出的结论是，立体定向身体放射治疗计划可能会使患者QA失败，但在周围几何中进行测量，但在集中几何中通过，可能与真正的临床偏差都没有相关性。
