Saini Amarjit, Tichacek Chris, Johansson William, Redler Gage, Zhang Geoffrey, Moros Eduardo G, Qayyum Muqeem, Feygelman Vladimir
Department of Radiation Oncology, Moffitt Cancer Center, Tampa, FL, USA.
RaySearch Americas Inc, New York, NY, USA.
J Appl Clin Med Phys. 2021 Feb;22(2):21-34. doi: 10.1002/acm2.13116. Epub 2021 Jan 15.
The Halcyon™ platform is self-contained, combining a treatment planning (Eclipse) system TPS) with information management and radiation delivery components. The standard TPS beam model is configured and locked down by the vendor. A portal dosimetry-based system for patient-specific QA (PSQA) is also included. While ensuring consistency across the user base, this closed model may not be optimal for every department. We set out to commission independent TPS (RayStation 9B, RaySearch Laboratories) and PSQA (PerFraction, Sun Nuclear Corp.) systems for use with the Halcyon linac. The output factors and PDDs for very small fields (0.5 × 0.5 cm ) were collected to augment the standard Varian dataset. The MLC leaf-end parameters were estimated based on the various static and dynamic tests with simple model fields and honed by minimizing the mean and standard deviation of dose difference between the ion chamber measurements and RayStation Monte Carlo calculations for 15 VMAT and IMRT test plans. Two chamber measurements were taken per plan, in the high (isocenter) and lower dose regions. The ratio of low to high doses ranged from 0.4 to 0.8. All percent dose differences were expressed relative to the local dose. The mean error was 0.0 ± 1.1% (TG119-style confidence limit ± 2%). Gamma analysis with the helical diode array using the standard 3%Global/2mm criteria resulted in the average passing rate of 99.3 ± 0.5% (confidence limit 98.3%-100%). The average local dose error for all detectors across all plans was 0.2% ± 5.3%. The ion chamber results compared favorably with our recalculation with Eclipse and PerFraction, as well as with several published Eclipse reports. Dose distribution gamma analysis comparisons between RayStation and PerFraction with 2%Local/2mm criteria yielded an average passing rate of 98.5% ± 0.8% (confidence limit 96.9%-100%). It is feasible to use the Halcyon accelerator with independent planning and verification systems without sacrificing dosimetric accuracy.
Halcyon™平台是一个独立的系统，它将治疗计划（Eclipse）系统TPS与信息管理和放射治疗组件相结合。标准的TPS射束模型由供应商进行配置和锁定。同时还包括一个基于射野剂量学的患者特定质量保证（PSQA）系统。在确保用户群体一致性的同时，这种封闭模型可能并非对每个科室都是最优的。我们着手启用独立的TPS（RayStation 9B，RaySearch Laboratories）和PSQA（PerFraction，Sun Nuclear Corp.）系统，以便与Halcyon直线加速器配合使用。收集了非常小射野（0.5×0.5 cm）的输出因子和百分深度剂量（PDD），以扩充标准的瓦里安数据集。基于对简单模型射野的各种静态和动态测试，估计了多叶准直器（MLC）叶片末端参数，并通过最小化15个容积调强放疗（VMAT）和调强放疗（IMRT）测试计划的电离室测量值与RayStation蒙特卡罗计算值之间剂量差异的均值和标准差进行了优化。每个计划在高剂量（等中心）和低剂量区域进行两次电离室测量。低剂量与高剂量的比值范围为0.4至0.8。所有剂量百分比差异均相对于局部剂量表示。平均误差为0.0±1.1%（TG119式置信限±2%）。使用标准的3%全局/2 mm标准，通过螺旋二极管阵列进行的伽马分析得出平均通过率为99.3±0.5%（置信限98.3%-100%）。所有计划中所有探测器的平均局部剂量误差为0.2%±5.3%。电离室测量结果与我们使用Eclipse和PerFraction进行的重新计算以及多篇已发表的Eclipse报告相比，结果良好。使用2%局部/2 mm标准，RayStation和PerFraction之间的剂量分布伽马分析比较得出平均通过率为98.5%±0.8%（置信限96.9%-100%）。使用Halcyon加速器与独立的计划和验证系统配合使用，同时不牺牲剂量学准确性是可行的。
