PDF(Pubmed)
Abstract：
We have clinically implemented gated stereotactic body radiotherapy under abdominal compression using an Anzai laser-based gating device with visual guidance in combination with an Elekta linear accelerator. To ensure accuracy, we configured the gating window for each patient by correlating the respiratory curve from the laser sensor and the tumor positions from the 4D computed tomography (CT) images reconstructed with the aid of the respiratory curve. This allowed us to define a patient-specific gating window to keep the tumor displacement below 5 mm from the end-expiration, assuming the reproducibility of the tumor trajectories and the laser-based body surface measurements. Results are summarized as follows: 1) A patient-specific gating window internal target volume (ITV) with a prespecified maximum tumor displacement relative to the end-expiration was obtained by acquiring a 4D CT consisting of 20 phase CT sets and a respiratory curve from the Anzai system. 2) Respiratory hysteresis was managed by setting two different thresholds on the respiratory curve based on the predetermined maximum tumor displacement relative to end-expiration. 3) Abdominal compression increased gating window width, thereby presumably leading to faster gated-beam delivery. 4) Gamma index pass rates in sliding-window gated intensity-modulated radiotherapy (IMRT) were superior to those in gated volumetric modulated arc therapy (VMAT). 5) Intrafraction gated cone-beam computed tomography (CBCT) demonstrated that the tumor appeared to remain within the gating window ITV during the stereotactic gated sliding-window IMRT. In conclusion, we have successfully implemented gated stereotactic body radiotherapy at our clinic and achieved a favorable clinical validation result. More cases need to be evaluated to increase the validity.
摘要：
我们已经使用基于Anzai激光的门控设备与视觉引导结合Elekta线性加速器，在腹部压迫下实施了门控立体定向放射治疗。为了确保准确性，我们通过关联来自激光传感器的呼吸曲线和来自借助呼吸曲线重建的4D计算机断层扫描(CT)图像的肿瘤位置,为每位患者配置了门控窗口.这使我们能够定义一个患者特定的门控窗口，以保持肿瘤位移在5毫米以下，从结束呼气，假设肿瘤轨迹的可重复性和基于激光的体表测量。结果总结如下：1）通过采集由20个相位CT集和呼吸曲线组成的4DCT，获得了患者特定的门控窗口内部目标体积（ITV），该目标体积相对于呼气末具有预定的最大肿瘤位移。来自Anzai系统。2)通过基于预定的相对于呼气末的最大肿瘤位移在呼吸曲线上设置两个不同的阈值来管理呼吸滞后。3)腹部压缩增加门控窗口宽度，从而可能导致更快的门控光束传输。4）滑窗门控调强放疗（IMRT）的伽马指数通过率优于门控体积调强治疗（VMAT）。5）帧内门控锥形束计算机断层扫描（CBCT）表明，在立体定向门控滑动窗口IMRT期间，肿瘤似乎仍保留在门控窗口ITV内。总之,我们在临床上成功实施了门控立体定向放射治疗，并取得了良好的临床验证结果。需要评估更多的案例以提高有效性。
