Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
Division of Medical Physics, Department of Information Technology and Medical Engineering, Human Health Sciences, Graduate School of Medicine, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
Radiat Oncol. 2019 Apr 11;14(1):62. doi: 10.1186/s13014-019-1264-6.
To perform quality assurance of non-coplanar, volumetric-modulated arc therapy featuring continuous couch rotation (CCR-VMAT) using a C-arm linear accelerator.
We planned and delivered CCR-VMAT using the TrueBeam Developer Mode. Treatment plans were created for both a C-shaped phantom and five prostate cancer patients using seven CCR trajectories that lacked collisions; we used RayStation software (ver. 4.7) to this end. Subsequently, verification plans were generated. The mean absolute error (MAE) between the center of an MV-imaged steel ball and the radiation field was calculated using the Winston-Lutz test. The MAEs between planned and actual irradiation values were also calculated from trajectory logs. In addition, correlation coefficients (r values) among the MAEs of gantry angle, couch angle, and multi-leaf collimator (MLC) position, and mechanical parameters including gantry speed, couch speed, MLC speed, and beam output, were estimated. The dosimetric accuracies of planned and measured values were also assessed using ArcCHECK.
The MAEs ±2 standard deviations as revealed by the Winston-Lutz test for all trajectories were 0.3 ± 0.3 mm in two dimensions. The MAEs of the gantry, couch, and MLC positions calculated from all trajectory logs were within 0.04°, 0.08°, and 0.02 mm, respectively. Deviations in the couch angle (r = 0.98, p < 0.05) and MLC position (r = 0.86, p < 0.05) increased significantly with speed. The MAE of the beam output error was less than 0.01 MU. The mean gamma passing rate ± 2 SD (range) of the 3%/3 mm, 3%/1 mm, and 5%/1 mm was 98.1 ± 1.9% (95.7-99.6%), 87.2 ± 2.8% (80.2-96.7%), and 96.3 ± 2.8% (93.9-99.6%), respectively.
CCR-VMAT delivered via the TrueBeam Developer Mode was associated with high-level geometric and mechanical accuracy, thus affording to high dosimetric accuracy. The CCR-VMAT performance was stable regardless of the trajectory chosen.
使用带有连续治疗床旋转（CCR）的 C 臂直线加速器对非共面容积调强弧形治疗进行质量保证。
我们使用 TrueBeam 开发者模式规划和实施 CCR-VMAT。使用 RayStation 软件（版本 4.7）为一个 C 形模体和五个前列腺癌患者制定了七个无碰撞的 CCR 轨迹的治疗计划。随后，生成了验证计划。使用 Winston-Lutz 测试计算 MV 成像钢球中心与辐射野之间的平均绝对误差（MAE）。还从轨迹日志中计算了计划和实际照射值之间的 MAE。此外，还估计了 MAE 与准直器角度、治疗床角度和多叶准直器（MLC）位置之间的相关系数（r 值），以及与机架速度、治疗床速度、MLC 速度和射束输出相关的机械参数。还使用 ArcCHECK 评估了计划值和测量值的剂量学准确性。
所有轨迹的 Winston-Lutz 测试的 MAE ±2 标准差在二维空间均为 0.3 ± 0.3mm。从所有轨迹日志中计算出的准直器、治疗床和 MLC 位置的 MAE 分别在 0.04°、0.08°和 0.02mm 以内。治疗床角度（r=0.98，p<0.05）和 MLC 位置（r=0.86，p<0.05）的偏差随速度显著增加。射束输出误差的 MAE 小于 0.01 MU。3%/3mm、3%/1mm 和 5%/1mm 的平均伽马通过率±2 SD（范围）分别为 98.1 ± 1.9%（95.7-99.6%）、87.2 ± 2.8%（80.2-96.7%）和 96.3 ± 2.8%（93.9-99.6%）。
通过 TrueBeam 开发者模式实施的 CCR-VMAT 具有较高的几何和机械精度，因此具有较高的剂量学准确性。无论选择哪种轨迹，CCR-VMAT 的性能都很稳定。
