Division of Medical Physics, Department of Radiation Oncology, Tata Medical Center, Kolkata, West Bengal, India.
Department of Physics, School of Advanced Sciences, Vellore Institute of Technology, Vellore, Tamil Nadu, India.
Asian Pac J Cancer Prev. 2024 Aug 1;25(8):2861-2868. doi: 10.31557/APJCP.2024.25.8.2861.
This study addresses challenges in delivering high radiation doses and managing organ motion in Stereotactic Body Radiation Therapy (SBRT) for thoracic and abdominal cancer. It evaluates Varian's Real Time Position Management (RPM) system's infrared camera sensitivity during crucial Four-Dimensional computed tomography (4D-CT) scans for planning and treatment. The analysis includes CT simulator, LINAC (Novalis Tx and TrueBeam STx). This research enhances SBRT precision by offering insights into RPM and RGSC system performance across machines, impacting treatment planning and delivery optimization.
The QUASAR™ Respiratory Motion Assembly phantom is aligned with precision using lasers. It is configured with either six-dot reflective or four-dot lens marker blocks featuring a retroreflective marker placed on the phantom's surface. Motion is induced by adjusting the amplitude, and the camera position is finely tuned to monitor the marker's movements. This investigation entails variations in seconds per breath (SPB) within the Quasar breath platform, specifically at intervals of 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 seconds while maintaining a 1cm amplitude camera setting.
For TrueBeam-STx: Ensure SPB values are kept above 1.8 seconds for accurate replication. For Novalis-Tx: Stay within an SPB range of up to 2.0 seconds for reliable reproducibility. For CT Simulator: Optimal replication up to an SPB of 2.2 seconds; avoid SPB values below 1.8 seconds for reliable detection.
Data for TrueBeam-STx, Novalis-Tx, and the CT simulator shows discrepancies in replicating the breathing cycle as Seconds Per Breath (SPB) decreases. Effective Infrared (IR) sensitivity is observed until SPB thresholds: 1.8s (TrueBeam-STx), 2.2s (Novalis-Tx), and 2.2s (CT simulator). We should consider values equal to or greater than the mentioned breathing periods. Variations in replicating breathing cycles signal challenges in planning and delivering treatments, especially with lower SPB values. These insights guide clinicians to adapt treatments based on machine-specific capabilities for accurate and reproducible outcomes.
本研究旨在解决胸腹部癌症立体定向体部放射治疗（SBRT）中高剂量辐射传递和器官运动管理的挑战。评估瓦里安的实时位置管理（RPM）系统在计划和治疗中进行关键的四维计算机断层扫描（4D-CT）时的红外摄像机灵敏度。该分析包括 CT 模拟器、直线加速器（Novalis Tx 和 TrueBeam STx）。通过提供跨机器的 RPM 和 RGSC 系统性能的见解，本研究提高了 SBRT 的精度，从而影响治疗计划和交付的优化。
使用激光将 QUASAR™呼吸运动组件体模精确定位。它配置有六个点反射或四个点透镜标记块，在体模表面放置一个后向反射标记。通过调整幅度来诱导运动，并微调摄像机位置以监测标记的运动。本研究在 Quasar 呼吸平台内变化了每呼吸秒数（SPB），具体在 2.0、2.5、3.0、3.5、4.0、4.5 和 5.0 秒之间变化，同时保持摄像机设置为 1cm 幅度。
对于 TrueBeam-STx：确保 SPB 值保持在 1.8 秒以上以实现准确复制。对于 Novalis-Tx：保持在 2.0 秒以内的 SPB 范围以实现可靠的再现性。对于 CT 模拟器：在 SPB 高达 2.2 秒的情况下实现最佳复制；避免 SPB 值低于 1.8 秒以实现可靠检测。
TrueBeam-STx、Novalis-Tx 和 CT 模拟器的数据显示，随着每呼吸秒数（SPB）的减少，复制呼吸周期的差异。在 SPB 阈值下观察到有效的红外（IR）灵敏度：1.8s（TrueBeam-STx）、2.2s（Novalis-Tx）和 2.2s（CT 模拟器）。我们应该考虑等于或大于所述呼吸周期的数值。复制呼吸周期的变化表明在计划和提供治疗方面存在挑战，尤其是在较低的 SPB 值下。这些见解指导临床医生根据机器的特定能力来调整治疗，以实现准确和可重复的结果。
