Nelson Christopher, Starkschall George, Balter Peter, Fitzpatrick Mathew J, Antolak John A, Tolani Naresh, Prado Karl
Department of Radiation Physics, The University of Texas M D Anderson Cancer Center Houston, Texas 77030, USA.
Med Phys. 2005 Jan;32(1):175-81. doi: 10.1118/1.1836332.
Respiratory motion causes movement of internal structures in the thorax and abdomen, making accurate delivery of radiation therapy to tumors in those areas a challenge. To reduce the uncertainties caused by this motion, we have developed feedback-guided breath hold (FGBH), a novel delivery technique in which radiation is delivered only during a voluntary breath hold that is sustained for as long as the patient feels comfortable. Here we present the technical aspects of FGBH, which involve (1) fabricating the hardware so the respiratory trace can be displayed to the patient, (2) assembling a delay box to be used as a breath-hold detector, and (3) performing quality control tests to ensure that FGBH can be delivered accurately and safely. A commercial respiratory tracking system that uses an external fiducial to monitor abdominal wall motion generates and displays the breathing trace and specific positions in the breathing cycle where a breath hold needs to occur. Hardware was developed to present this display to the patient in the treatment position. Patients view the presentation either on a liquid crystal display or through a pair of virtual reality goggles. Using the respiratory trace as a visual aid, the patient performs a breath hold so that the position representing the location of a fiducial is held within a specified gating window. A delay box was fabricated to differentiate between gating signals received during free breathing and those received during breath hold, allowing radiation delivery only when the fiducial was within the breath-hold gating window. A quality control analysis of the gating delay box and the integrated system was performed to ensure that all of the hardware and components were ready for clinical use.
呼吸运动导致胸部和腹部内部结构的移动，使得向这些区域的肿瘤精确输送放射治疗成为一项挑战。为了减少这种运动引起的不确定性，我们开发了反馈引导屏气（FGBH）技术，这是一种新颖的输送技术，其中放射治疗仅在患者感觉舒适的情况下持续进行的自主屏气期间进行。在此，我们介绍FGBH的技术方面，包括（1）制造硬件以便向患者显示呼吸轨迹，（2）组装用作屏气检测器的延迟盒，以及（3）进行质量控制测试以确保FGBH能够准确且安全地实施。一种使用外部基准标记来监测腹壁运动的商用呼吸跟踪系统会生成并显示呼吸轨迹以及呼吸周期中需要进行屏气的特定位置。我们开发了硬件，以便在治疗位置向患者呈现此显示。患者可以在液晶显示屏上观看，也可以通过一副虚拟现实护目镜观看。利用呼吸轨迹作为视觉辅助，患者进行屏气，以使代表基准标记位置的点保持在指定的门控窗口内。制造了一个延迟盒，以区分自由呼吸期间接收到的门控信号和屏气期间接收到的信号，仅在基准标记位于屏气门控窗口内时才允许进行放射治疗。对门控延迟盒和集成系统进行了质量控制分析，以确保所有硬件和组件都可用于临床。
