Department of Radiation Oncology, Stanford University, Stanford, California, USA.
RefleXion Medical, Inc., Hayward, California, USA.
J Appl Clin Med Phys. 2022 Aug;23(8):e13638. doi: 10.1002/acm2.13638. Epub 2022 May 29.
The RefleXion X1 is a novel radiotherapy machine designed for image-guided radiotherapy (IGRT) and biology-guided radiotherapy (BgRT). Its treatment planning system (TPS) generates IMRT and SBRT plans for a 6MV-FFF beam delivered axially via 50 firing positions with the couch advancing every 2.1 mm. The purpose of this work is to report the TPS commissioning results for the first clinical installation of RefleXion™ X1.
CT images of multiple phantoms were imported into the RefleXion TPS to evaluate the accuracy of data transfer, anatomical modeling, plan evaluation, and dose calculation. Comparisons were made between the X1, Eclipse™, and MIM™. Dosimetric parameters for open static fields were evaluated in water and heterogeneous slab phantoms. Representative clinical IMRT and SBRT cases were planned and verified with ion chamber, film, and ArcCHECK measurements. The agreement between TPS and measurements for various clinical plans was evaluated using Gamma analysis with a criterion of 3%/2 mm for ArcCHECK and film. End-to-end (E2E) testing was performed using anthropomorphic head and lung phantoms.
The average difference between the TPS-reported and known HU values was -1.4 ± 6.0 HU. For static fields, the agreements between the TPS-calculated and measured PDD , crossline profiles, and inline profiles (FWHM) were within 1.5%, 1.3%, and 0.5 mm, respectively. Measured output factors agreed with the TPS within 1.3%. Measured and calculated dose for static fields in heterogeneous phantoms agreed within 2.5%. The ArcCHECK mean absolute Gamma passing rate was 96.4% ± 3.4% for TG 119 and TG 244 plans and 97.8% ± 3.6% for the 21 clinical plans. E2E film analysis showed 0.8 mm total targeting error for isocentric and 1.1 mm for off-axis treatments.
The TPS commissioning results of the RefleXion X1 TPS were within the tolerances specified by AAPM TG 53, MPPG 5.a, TG 119, and TG 148. A subset of the commissioning tests has been identified as baseline data for an ongoing QA program.
RefleXion X1 是一种新型的放射治疗机，专为图像引导放射治疗（IGRT）和生物学引导放射治疗（BgRT）而设计。其治疗计划系统（TPS）为 6MV-FFF 射线生成调强放射治疗（IMRT）和立体定向放射治疗（SBRT）计划，通过 50 个发射位置轴向传输，治疗床每 2.1mm 推进一次。本工作的目的是报告第一台 RefleXion X1 临床安装的 TPS 调试结果。
将多个体模的 CT 图像导入 RefleXion TPS，以评估数据传输、解剖建模、计划评估和剂量计算的准确性。将 X1、Eclipse 和 MIM 进行了比较。在水和不均匀平板体模中评估了开放静态场的剂量学参数。使用电离室、胶片和 ArcCHECK 测量对代表性的临床 IMRT 和 SBRT 病例进行了计划和验证。使用 3%/2mm 的 Gamma 分析标准评估了各种临床计划的 TPS 和测量结果的一致性，ArcCHECK 和胶片的标准为 3%/2mm。使用人体头部和肺部体模进行端到端（E2E）测试。
TPS 报告的和已知 HU 值之间的平均差异为-1.4±6.0HU。对于静态场，TPS 计算的和测量的 PDD、交叉线轮廓和内线轮廓（FWHM）之间的一致性分别在 1.5%、1.3%和 0.5mm 以内。测量的输出因子与 TPS 之间的一致性在 1.3%以内。不均匀体模中静态场的测量和计算剂量之间的一致性在 2.5%以内。ArcCHECK 平均绝对 Gamma 通过率对于 TG 119 和 TG 244 计划分别为 96.4%±3.4%，对于 21 个临床计划分别为 97.8%±3.6%。E2E 胶片分析显示，等中心治疗的总靶区误差为 0.8mm，偏心治疗的总靶区误差为 1.1mm。
RefleXion X1 TPS 的 TPS 调试结果符合 AAPM TG 53、MPPG 5.a、TG 119 和 TG 148 规定的容差。已确定调试测试的一部分作为正在进行的 QA 计划的基线数据。
