Proton range verification using a range probe: definition of concept and initial analysis
Proton range verification using a range probe: definition of concept and initial analysis
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DOI：
10.1088/0031-9155/55/16/010
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发表时间：
2010-08-21
影响因子：
3.5
通讯作者：
Lomax, A. J.
中科院分区：
文献类型：
--
作者：
Mumot, M.;Algranati, C.;Lomax, A. J.
质子治疗可能对范围的变化或误差特别敏感。因此，用于在体内测量范围的方法可以是非常有用的，以提高质子为基础的放射治疗的质量和准确性。在本文中，我们介绍了“范围探头”的概念。这是一种低剂量、高能量的质子笔形射束，将穿过患者，并且其积分布拉格峰将使用多层探测器在出射侧测量。我们建议，通过比较测量的积分布拉格峰与计算的基础上，患者的计划CT，这样的范围探头可以提供有用的信息，在体内的范围计算的准确性。为了研究这种方法的可行性，已经进行了基于蒙特卡罗的研究。使用患者的计划CT，MC模拟（VMCpro）已经为单笔形光束横向穿过头部和停止在患者后面的模拟范围望远镜。距离探头已计算不同的位置，并从布拉格峰的距离望远镜的“信号”的剩余范围已被评估为不同的假设探测器厚度。这种方法的灵敏度CT值的变化，校准曲线和CT的位置偏移进行了研究。根据我们的分析，对于均匀区域，探测器厚度为4 mm时，1 mm的范围分辨率是可能的。此外，对于异质区域，由于CT的空间移位而引起的布拉格峰形状的变化可以是用于直接在治疗位置中检测患者设置错误的灵敏测量。质子“距离探测器”的概念似乎对高分辨率距离核查是可行的。我们现在想用不同的可能的距离望远镜探测器来实验性地测试这个概念。
Proton therapy can be particularly sensitive to changes or errors in range. Thus, methods for the in vivo measurement of range could be of great use to improve the quality and accuracy of proton-based radiotherapy. In this paper, we introduce the concept of the 'range probe'. This is a low-dose, high-energy proton pencil beam that would pass through a patient, and whose integral Bragg peak would be measured on the exit side using a multi-layer detector. We propose that by comparing the measured integral Bragg peak with that calculated based on the patient's planning CT, such a range probe could provide useful information about the accuracy of range calculations in vivo. To study the feasibility of this approach, a Monte Carlo-based study has been performed. Using a patient's planning CT, MC simulations (VMCpro) have been made for single pencil beams laterally traversing the head and stopping in a simulated range telescope behind the patient. Range probes have been calculated for different locations, and the residual range from the Bragg peak 'signal' in the range telescope has been assessed for different assumed detector thicknesses. The sensitivity of this approach to changes in CT values, calibration curve and positional shifts of the CT have been investigated. From our analysis, range resolutions of 1 mm may be possible with a detector thickness of 4 mm for homogeneous regions. Additionally, for heterogeneous regions, changes of the Bragg peak shape due to spatial shifts of the CT could be a sensitive measure for detecting patient set-up errors directly in the treatment position. The concept of the proton 'range probe' appears to be feasible for high-resolution range verification. We now want to test this concept experimentally using different possible range telescope detectors.