The Elekta Unity MR‐linac utilizes daily magnetic resonance imaging (MRI) for online plan adaptation. In the Unity workflow, adapt to position (ATP) and adapt to shape (ATS) treatment planning options are available which represent a virtual shift or full re‐plan with contour adjustments respectively. Both techniques generate a new intensity modulated radiation therapy (IMRT) treatment plan while the patient lies on the treatment table and thus adapted plans cannot be measured prior to treatment delivery. A statistical process control methodology was used to analyze 512 patient‐specific IMRT QA measurements performed on the MR‐compatible SunNuclear ArcCheck with a gamma criterion of 3%/2 mm using global normalization and a 10% low dose threshold. The lower control limit (LCL) was determined from 68 IMRT reference plan measurements, and a one‐sided process capability ratio was used to assess the pass rates from 432 measured ATP and 80 measured ATS plans. Further analysis was performed to assess differences between SBRT or conventional fractionation pass rates and to determine whether there was any correlation between the pass rates and plan complexity. The LCL of the reference plans was determined to be a gamma pass rate of 0.958, and the of the measured ATP plans and measured ATS plans were determined to be 1.403 and 0.940 for ATP and ATS plans, respectively, while a of 0.902 and 1.383 was found for SBRT and conventional fractionations respectively. For plan complexity, no correlation was found between modulation degree and gamma pass rate, but a statistically significant correlation was observed between the beam‐averaged aperture area and gamma pass rate. All adaptive plans passed the TG‐218 guidelines, but the ATS and SBRT plans tended to have a smaller beam‐averaged aperture area with slightly lower gamma pass rates.

中文翻译：

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使用统计过程控制方法分析 Elekta Unity 自适应计划的患者特定质量保证

Elekta Unity MR-linac 利用每日磁共振成像 (MRI) 进行在线计划调整。在 Unity 工作流程中，可以使用适应位置 (ATP) 和适应形状 (ATS) 治疗计划选项，它们分别代表虚拟移位或通过轮廓调整进行完全重新计划。当患者躺在治疗台上时，这两种技术都会生成新的调强放射治疗 (IMRT) 治疗计划，因此在治疗实施之前无法测量调整后的计划。使用统计过程控制方法来分析在 MR 兼容 SunNuclear ArcCheck 上进行的 512 项患者特异性 IMRT QA 测量，使用全局标准化和 10% 低剂量阈值，伽马标准为 3%/2 mm。控制下限（LCL）是根据 68 个 IMRT 参考计划测量确定的，并使用单侧过程能力比来评估 432 个测量的 ATP 和 80 个测量的 ATS 计划的通过率。进行了进一步的分析，以评估 SBRT 或传统分割通过率之间的差异，并确定通过率和计划复杂性之间是否存在任何相关性。参考计划的 LCL 确定为 0.958 的 gamma 通过率，测量的 ATP 计划和测量的 ATS 计划的 ATP 和 ATS 计划的 分别确定为 1.403 和 0.940，而 a为 0.902 和 1.383分别针对 SBRT 和常规分馏发现。对于计划复杂性，在调制程度和伽马通过率之间没有发现相关性，但在光束平均孔径面积和伽马通过率之间观察到统计上显着的相关性。所有自适应计划均通过了 TG-218 准则，但 ATS 和 SBRT 计划往往具有较小的光束平均孔径面积，且伽玛通过率略低。