Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
Sun Nuclear Corporation, 3275 Suntree Boulevard, Melbourne, FL, 32940, USA.
J Appl Clin Med Phys. 2019 Oct;20(10):111-117. doi: 10.1002/acm2.12719. Epub 2019 Sep 25.
We tested whether an ionization chamber array (ICA) and a one-dimensional water scanner (1DS) could be used instead of a three-dimensional water scanning system (3DWS) for acceptance testing and commissioning verification of the Varian Halcyon-Eclipse Treatment Planning System (TPS). The Halcyon linear accelerator has a single 6-MV flattening-filter-free beam and a nonadjustable beam model for the TPS. Beam data were measured with a 1DS, ICA, ionization chambers, and electrometer. Acceptance testing and commissioning were done simultaneously by comparing the measured data with TPS-calculated percent-depth-dose (PDD) and profiles. The ICA was used to measure profiles of various field sizes (10-, 20-, and 28 cm ) at depths of d (1.3 cm), 5-, 10-, and 20 cm. The 1DS was used for output factors (OFs) and PDDs. OFs were measured with 1DS for various fields (2-28 cm ) at a source-to-surface distance of 90 cm. All measured data were compared with TPS-calculations. Profiles, off-axis ratios (OAR), PDDs and OFs were also measured with a 3DWS as a secondary check. Profiles between the ICA and TPS (ICA and 3DWS) at various depths across the fields indicated that the maximum discrepancies in high-dose and low-dose tail were within 2% and 3%, respectively, and the maximum distance-to-agreement in the penumbra region was <3 mm. The largest OAR differences between ICA and TPS (ICA and 3DWS) values were 0.23% (-0.25%) for a 28 × 28 cm field, and the largest point-by-point PDD differences between 1DS and TPS (1DS and 3DWS) were -0.41% ± 0.12% (-0.32% ± 0.17%) across the fields. Both OAR and PDD showed the beam energy is well matched to the TPS model. The average ratios of 1DS-measured OFs to the TPS (1DS to 3DWS) values were 1.000 ± 0.002 (0.999 ± 0.003). The Halcyon-Eclipse system can be accepted and commissioned without the need for a 3DWS.
我们测试了电离室阵列（ICA）和一维水扫描器（1DS）是否可以代替三维水扫描系统（3DWS），用于验证瓦里安 Halcyon-Eclipse 治疗计划系统（TPS）的验收测试和调试。Halcyon 直线加速器有一个单一的 6MV 无均整过滤器束和一个不可调节的束模型用于 TPS。束数据使用 1DS、ICA、电离室和静电计进行测量。通过比较测量数据与 TPS 计算的百分深度剂量（PDD）和曲线，同时进行验收测试和调试。ICA 用于测量各种射野大小（10、20 和 28cm）在深度 d（1.3cm）、5、10 和 20cm 处的曲线。1DS 用于测量输出因子（OFs）和 PDDs。在源皮距为 90cm 的情况下，使用 1DS 测量各种射野（2-28cm）的 OFs。所有测量数据均与 TPS 计算值进行比较。3DWS 还用于测量曲线、离轴比（OAR）、PDD 和 OFs，作为二次检查。在射野的各个深度处，ICA 和 TPS（ICA 和 3DWS）之间的曲线、离轴比（OAR）、PDD 和 OFs 的测量结果表明，高剂量和低剂量尾部的最大差异分别在 2%和 3%以内，半影区的最大符合距离<3mm。ICA 和 TPS（ICA 和 3DWS）之间最大的 OAR 差异为 28×28cm 射野的 0.23%（-0.25%），1DS 和 TPS（1DS 和 3DWS）之间最大的 PDD 差异为 -0.41%±0.12%（-0.32%±0.17%）。OAR 和 PDD 均表明束能量与 TPS 模型很好地匹配。1DS 测量的 OFs 与 TPS（1DS 到 3DWS）值的平均比值为 1.000±0.002（0.999±0.003）。不需要 3DWS 即可接受和调试 Halcyon-Eclipse 系统。
