Saito Nami, Bert Christoph, Chaudhri Naved, Gemmel Alexander, Schardt Dieter, Durante Marco, Rietzel Eike
GSI Helmholtz Centre for Heavy Ion Research GmbH, Planckstrasse 1, 64291 Darmstadt, Germany.
Phys Med Biol. 2009 Aug 21;54(16):4849-62. doi: 10.1088/0031-9155/54/16/001. Epub 2009 Jul 27.
The technical performance of an integrated three-dimensional carbon ion pencil beam tracking system that was developed at GSI was investigated in phantom studies. Aim of the beam tracking system is to accurately treat tumours that are subject to respiratory motion with scanned ion beams. The current system provides real-time control of ion pencil beams to track a moving target laterally using the scanning magnets and longitudinally with a dedicated range shifter. The system response time was deduced to be approximately 1 ms for lateral beam tracking. The range shifter response time has been measured for various range shift amounts. A value of 16 +/- 2 ms was achieved for a water equivalent shift of 5 mm. An additional communication delay of 11 +/- 2 ms was taken into account in the beam tracking process via motion prediction. Accuracy of the lateral beam tracking was measured with a multi-wire position detector to < or =0.16 mm standard deviation. Longitudinal beam tracking accuracy was parameterized based on measured responses of the range shifter and required time durations to maintain a specific particle range. For example, 5 mm water equivalence (WE) longitudinal beam tracking results in accuracy of 1.08 and 0.48 mm WE in root mean square for time windows of 10 and 50 ms, respectively.
在模体研究中对德国重离子研究中心（GSI）研发的集成三维碳离子笔形束扫描系统的技术性能进行了研究。束扫描系统的目的是利用扫描离子束精确治疗受呼吸运动影响的肿瘤。当前系统通过扫描磁铁对离子笔形束进行实时控制，以横向跟踪移动目标，并通过专用射程移位器纵向跟踪。横向束扫描的系统响应时间推断约为1毫秒。已针对各种射程移位量测量了射程移位器的响应时间。对于5毫米水等效移位，实现了16±2毫秒的值。在束扫描过程中，通过运动预测考虑了11±2毫秒的额外通信延迟。使用多丝位置探测器测量横向束扫描的精度，标准偏差≤0.16毫米。纵向束扫描精度是根据射程移位器的测量响应和保持特定粒子射程所需的持续时间进行参数化的。例如，对于5毫米水等效（WE）的纵向束扫描，在10毫秒和50毫秒的时间窗口内，均方根精度分别为1.08毫米WE和0.48毫米WE。
