Hoshina Masataka, Noguchi Masaya, Takanashi Masato, Masuda Kouichi, Sugahara Shinji
Department of Radiology and Radiation Oncology, Tokyo Medical University Ibaraki Medical Center, Inashiki-gun, JPN.
Cureus. 2024 May 4;16(5):e59638. doi: 10.7759/cureus.59638. eCollection 2024 May.
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.
我们已经在临床上实施了使用基于安齐激光的门控装置并结合视觉引导以及医科达直线加速器，在腹部加压下进行门控立体定向体部放射治疗。为确保准确性，我们通过将来自激光传感器的呼吸曲线与借助呼吸曲线重建的4D计算机断层扫描（CT）图像中的肿瘤位置相关联，为每位患者配置门控窗口。假设肿瘤轨迹和基于激光的体表测量具有可重复性，这使我们能够定义一个患者特异性的门控窗口，以使肿瘤在呼气末的位移保持在5毫米以下。结果总结如下：1）通过获取由20个相位CT集组成的4D CT和来自安齐系统的呼吸曲线，获得了相对于呼气末具有预先指定最大肿瘤位移的患者特异性门控窗口内部靶区（ITV）。2）通过基于相对于呼气末的预定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）腹部加压增加了门控窗口宽度，从而可能导致门控束流输送更快。4）滑动窗口门控调强放射治疗（IMRT）中的伽马指数通过率优于门控容积调强弧形治疗（VMAT）中的通过率。5）分次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，肿瘤似乎保持在门控窗口ITV内。总之，我们在我们的诊所成功实施了门控立体定向体部放射治疗，并取得了良好的临床验证结果。需要评估更多病例以提高有效性。
