Department of Advanced Radiation Oncology and Proton Therapy, Inova Schar Cancer Institute, Fairfax, Virginia, USA.
Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
J Appl Clin Med Phys. 2024 Aug;25(8):e14352. doi: 10.1002/acm2.14352. Epub 2024 May 2.
To design a patient specific quality assurance (PSQA) process for the CyberKnife Synchrony system and quantify its dosimetric accuracy using a motion platform driven by patient tumor traces with rotation.
The CyberKnife Synchrony system was evaluated using a motion platform (MODUSQA) and a SRS MapCHECK phantom. The platform was programed to move in the superior-inferior (SI) direction based on tumor traces. The detector array housed by the StereoPhan was placed on the platform. Extra rotational angles in pitch (head down, 4.0° ± 0.15° or 1.2° ± 0.1°) were added to the moving phantom to examine robot capability of angle correction during delivery. A total of 15 Synchrony patients were performed SBRT PSQA on the moving phantom. All the results were benchmarked by the PSQA results based on static phantom.
For smaller pitch angles, the mean gamma passing rates were 99.75% ± 0.87%, 98.63% ± 2.05%, and 93.11% ± 5.52%, for 3%/1 mm, 2%/1 mm, and 1%/1 mm, respectively. Large discrepancy in the passing rates was observed for different pitch angles due to limited angle correction by the robot. For larger pitch angles, the corresponding mean passing rates were dropped to 93.00% ± 10.91%, 88.05% ± 14.93%, and 80.38% ± 17.40%. When comparing with the static phantom, no significant statistic difference was observed for smaller pitch angles (p = 0.1 for 3%/1 mm), whereas a larger statistic difference was observed for larger pitch angles (p < 0.02 for all criteria). All the gamma passing rates were improved, if applying shift and rotation correction.
The significance of this work is that it is the first study to benchmark PSQA for the CyberKnife Synchrony system using realistically moving phantoms with rotation. With reasonable delivery time, we found it may be feasible to perform PSQA for Synchrony patients with a realistic breathing pattern.
为 CyberKnife Synchrony 系统设计一个特定于患者的质量保证 (PSQA) 流程，并使用带有旋转的患者肿瘤轨迹驱动的运动平台来量化其剂量学准确性。
使用运动平台 (MODUSQA) 和 SRS MapCHECK 体模对 CyberKnife Synchrony 系统进行评估。根据肿瘤轨迹，平台被编程在上下 (SI) 方向移动。装有 StereoPhan 的探测器阵列放置在平台上。在移动体模上增加额外的俯仰角（头朝下，4.0°±0.15°或 1.2°±0.1°），以检查机器人在输送过程中角校正的能力。对 15 名接受同步放射外科治疗的患者在运动体模上进行了 PSQA。所有结果均与静态体模的 PSQA 结果进行了基准测试。
对于较小的俯仰角，3%/1mm、2%/1mm 和 1%/1mm 的平均伽马通过率分别为 99.75%±0.87%、98.63%±2.05%和 93.11%±5.52%。由于机器人的角度校正有限，不同俯仰角的通过率存在较大差异。对于较大的俯仰角，相应的平均通过率降至 93.00%±10.91%、88.05%±14.93%和 80.38%±17.40%。与静态体模相比，较小俯仰角时无显著统计学差异（p=0.1 对于 3%/1mm），而较大俯仰角时存在较大统计学差异（所有标准均为 p<0.02）。如果应用移位和旋转校正，所有伽马通过率都有所提高。
这项工作的意义在于，它是第一项使用带有旋转的真实运动体模对 CyberKnife Synchrony 系统进行 PSQA 基准测试的研究。在合理的输送时间内，我们发现对具有真实呼吸模式的 Synchrony 患者进行 PSQA 可能是可行的。
