Department of Radiation Oncology, Amsterdam University Medical Center - location University of Amsterdam, Amsterdam, the Netherlands.
Department of Radiation Oncology, Amsterdam University Medical Center - location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
J Appl Clin Med Phys. 2023 May;24(5):e13905. doi: 10.1002/acm2.13905. Epub 2023 Jan 17.
The recently released Ethos therapy system (Varian Medical Systems) allows for online CBCT-guided adaptive radiation therapy (RT). The clinical introduction of multiple systems requires machine characterization and machine variation quantification to allow patient interchangeability between systems. Despite several clinical introductions, limited vendor-independent information on machine performance is available. Our aim was to determine the relevant dosimetric and mechanical characteristics of individual machines and to quantify machine variations.
Six Ethos treatment machines, equipped with a 6-MV FFF beam including dual-layer MLC and kV-CBCT system, were recently introduced clinically after extensive machine characterization and pre-configured beam model verification. Point doses and profiles were measured and compared to vendor-provided reference data and dose calculations. Also, dose calculations were verified based on point measurements for non-standard fields and dose distributions for optimized treatment plans. Agreements between dose profiles (dose distributions) were quantified using 1D (3D) γ-analysis. Additionally, we quantified leaf transmission, dosimetric leaf gap (DLG) and couch attenuation, determined isocenter accuracy and kV-MV isocenter coincidence and verified the kV-CBCT system. Machine variations were quantified for all dosimetric and mechanical characteristics.
For all machines, distinct agreements were found between measurements and vendor-provided reference data as well as measurements and dose calculations. Mean γ values for all profiles were below 0.30. All profiles, point measurements and dose distributions matched well among the six machines. Minimal machine variations were found in terms of DLG (0.05 mm), leaf transmission (0.001%), isocenter accuracy (0.08 mm), kV-MV isocenter coincidence (0.15 mm), couch attenuation (0.69%), and CBCT imaging dose (0.29 mGy).
This study demonstrates excellent agreement between individual Ethos therapy systems and vendor-provided reference data as well as a pre-configured beam model. Furthermore, our results show good consistency among all machines and provide valuable insights on relevant machine characteristics. The systematically obtained results provide benchmark data for future clinical introduction of Ethos therapy systems.
最近发布的 Ethos 治疗系统（Varian Medical Systems）允许在线 CBCT 引导自适应放射治疗（RT）。多个系统的临床引入需要对机器特性进行描述并对机器变化进行量化，以实现系统间患者的可互换性。尽管已经有几个系统投入临床使用，但关于机器性能的信息仍然有限，且不受供应商影响。我们的目的是确定各个机器的相关剂量学和机械特性，并量化机器变化。
六台配备 6-MVFFF 光束的 Ethos 治疗机器，包括双层 MLC 和千伏 CBCT 系统，在经过广泛的机器特性描述和预配置光束模型验证后，最近已在临床上投入使用。点剂量和剂量分布与供应商提供的参考数据和剂量计算进行了测量和比较。此外，还根据非标准野的点测量和优化治疗计划的剂量分布对剂量计算进行了验证。使用一维（三维）γ分析来量化剂量分布（剂量分布）之间的一致性。此外，我们量化了叶片传输、剂量学叶片间隙（DLG）和治疗床衰减，确定了等中心精度和千伏-MV 等中心重合度，并验证了千伏-CBCT 系统。对所有剂量学和机械特性进行了机器变化量化。
对于所有机器，测量值与供应商提供的参考数据以及测量值与剂量计算之间都存在明显的一致性。所有剂量分布的平均γ值均低于 0.30。六个机器之间所有剂量分布、点测量和剂量分布的匹配度都很好。在 DLG（0.05 毫米）、叶片传输（0.001%）、等中心精度（0.08 毫米）、千伏-MV 等中心重合度（0.15 毫米）、治疗床衰减（0.69%）和 CBCT 成像剂量（0.29 毫戈瑞）方面，机器变化最小。
本研究表明，Ethos 治疗系统与供应商提供的参考数据以及预配置的光束模型之间具有极好的一致性。此外，我们的结果表明，所有机器之间具有良好的一致性，并为相关机器特性提供了有价值的见解。系统地获得的结果为未来 Ethos 治疗系统的临床引入提供了基准数据。
