A respiratory-gated treatment system for proton therapy.
A respiratory-gated treatment system for proton therapy.
复制标题
DOI：
10.1007/978-3-540-36841-0_559
复制
发表时间：
2007-08
期刊：
影响因子：
3.8
通讯作者：
Hsiao-Ming Lu;R. Brett;G. Sharp;S. Safai;Steve B. Jiang;J. Flanz;H. Kooy
中科院分区：
文献类型：
--
作者：
Hsiao-Ming Lu;R. Brett;G. Sharp;S. Safai;Steve B. Jiang;J. Flanz;H. Kooy
质子治疗具有良好的剂量一致性和降低整体剂量。然而，优越的剂量分布对沿光束路径的辐射深度变化比光子场敏感得多。呼吸运动可引起治疗部位如肺、肝和纵隔结构的改变，从而显著影响质子剂量分布。我们已经开发并调试了一个呼吸门控光束控制系统，用于我们的距离调制治疗光束。实时位置管理（RPM, Varian Inc ., Palo Alto， CA）系统用于监测患者的呼吸周期并提供门控信号，该信号与范围调制信号相结合，以产生所需的回旋加速器束电流门控。门控电路的设计确保了整个调制周期的完成，因此对于任何波束段，所传递的剂量都具有精确的计划SOBP分布。这不可避免地引入了波束开/关的延迟，直至100毫秒的调制周期的长度。利用运动模体和时间分辨测量，我们测量了回旋束控制相对于RPM门控信号的响应延迟，以及RPM系统本身相对于实际机械运动模体的延迟。结果发现，回旋束电流响应延迟小于5 ms（我们测量能力的下限），而RPM系统的延迟为60-90ms，平均为75 ms。因此，光束的总门控延迟在65至195毫秒的范围内。利用运动模体进行了薄膜测试，以验证整个门控结果。
Proton therapy offers excellent dose conformality and reduction in integral dose. The superior dose distribution is, however, much more sensitive to changes in radiological depths along the beam path than for photon fields. Respiratory motion can cause such changes for treatments sites like lung, liver, and mediastinum structures, and thus affect the proton dose distribution significantly. We have developed and commissioned a respiratory-gated beam control system for our range-modulated treatment beam. A Real-time Position Management (RPM, Varian Inc, Palo Alto, CA) system was used to monitor the patient’s breathing cycle and to provide the gating signal, which is combined with the range modulation signal to generate the required gating control of the cyclotron beam current. The gating circuit has been designed to ensure the full modulation cycle is completed so that for any beam-on segment, the delivered dose has the exact planned SOBP distribution. This inevitably introduces a delay of the beam on/off up to the length of the modulation cycle of 100 ms. Using a motion phantom and time resolved measurement, we have measured the response delay of the cyclotron beam control relative to the RPM gating signal, as well as the delay of the RPM system itself relative to the actual mechanical motion of the phantom. It was found that while the cyclotron beam current response delay is less than 5 ms (the lower limit of the our measurement capability), the RPM system poses a delay of 60–90ms with an average of 75 ms. The total gating delay of the beam is thus in the range of 65 to 195 ms. Film test using a motion phantom was conducted to verify the overall gating results.