Izaguirre E W, Price S G, Smajlovic S, Yaddanapudi S, Wooten H, Mutic S
Washington University School of Medicine, Saint Louis, MO.
Nuclear Science and Engineering Institute, University of Missouri, Columbia, MO.
Med Phys. 2012 Jun;39(6Part12):3739. doi: 10.1118/1.4735217.
We studied the sensitivity of a novel transmission fiber scintillator array designed and built for in line treatment verification. The purpose of this project is to assess the capability of the fiber detector array technology to detect treatment errors in real time without false positives to enhance patient safety.
We developed a linear scintillator array detector using radiation hard scintillating fibers and high speed parallel signal conditioning and data acquisition to monitor external beam treatment fluence in real time. The detector captures and resolves the time and amplitude of each linac pulse at each MLC segment. The detector has 60 fibers aligned to each MLC leaf and two output channels per fiber. The data is captured by a high speed parallel digitizer to determine the IMRT beam output delivered to a patient in real time. We evaluated the detector peak pulse linearity according to dose rate, MLC positioning, and beam energy. We analyzed the detector sensitivity, signal to noise ratio, and pulse distribution statistics to determine beam output and fluence in real time.
We analyzed the response of the detector to 6 MV and 10 MV photon beams. The statistical analysis of the detected linac pulses indicates that a minimum of 20 pulses are required to evaluate MLC positioning and fluence with 3 mm and 3% resolution, respectively. During testing, no false positives were detected. Linearity with respect to output rate, MLC or jaw opening, and fluence is within 2%.
Measured sensitivity and signal to noise ratio of a real time linear fiber array detector show that delivered beam fluence can be monitored every 55 msec, with no observed false positives during treatment to provide in vivo real time patient safety and beam monitoring.
我们研究了一种为在线治疗验证而设计和制造的新型传输光纤闪烁体阵列的灵敏度。该项目的目的是评估光纤探测器阵列技术实时检测治疗误差而不产生误报的能力，以提高患者安全性。
我们开发了一种线性闪烁体阵列探测器，使用抗辐射闪烁光纤以及高速并行信号调节和数据采集来实时监测外照射治疗的注量。该探测器捕获并解析每个直线加速器脉冲在每个多叶准直器（MLC）段的时间和幅度。探测器有60根光纤与每个MLC叶片对齐，每根光纤有两个输出通道。数据由高速并行数字化仪捕获，以实时确定输送给患者的调强放射治疗（IMRT）射束输出。我们根据剂量率、MLC定位和射束能量评估了探测器的峰值脉冲线性度。我们分析了探测器的灵敏度、信噪比和脉冲分布统计数据，以实时确定射束输出和注量。
我们分析了探测器对6兆伏和10兆伏光子束的响应。对检测到的直线加速器脉冲的统计分析表明，分别以3毫米和3%的分辨率评估MLC定位和注量时，至少需要20个脉冲。在测试过程中，未检测到误报。在输出率、MLC或准直器开口以及注量方面的线性度在2%以内。
实时线性光纤阵列探测器的测量灵敏度和信噪比表明，每55毫秒可监测一次输送的射束注量，在治疗过程中未观察到误报，从而可提供体内实时患者安全和射束监测。
