Delft University of Technology, Delft, The Netherlands.
Phys Med Biol. 2012 Jan 21;57(2):297-308. doi: 10.1088/0031-9155/57/2/297. Epub 2011 Dec 9.
In this paper we report on Monte Carlo simulations to investigate real-time monitoring of the track depth profile in particle therapy by measuring prompt gamma ray emissions: a high sensitivity imaging system employing a knife-edge-shaped slit combined with a position-sensitive gamma detector was evaluated. Calculations to test this new concept were performed for a head-sized software phantom. Clear spatial correlation is shown between the distribution of gamma rays detected with energies above 1.5 MeV and the distribution of prompt gamma rays emitted from the phantom. The number of neutrons originating from nuclear reactions in the phantom that are detected at these high energies is small. Most importantly it is shown that under common therapy conditions enough data may be collected during one spot-step (of the order of 10 ms) to locate the distal dose edge with a 1σ accuracy of better than 1 mm. This indicates that simple slit cameras have high potential for accurate real-time particle therapy adjustment and may become a practical way to improve particle therapy accuracy.
本文报告了蒙特卡罗模拟研究，通过测量瞬发伽马射线发射来实时监测粒子治疗中的轨迹深度分布：评估了一种采用刀口形狭缝结合位置灵敏伽马探测器的高灵敏度成像系统。针对这个新概念进行了计算测试，使用了一个头部大小的软件体模。结果显示，在 1.5MeV 以上能量探测到的伽马射线分布与从体模发射的瞬发伽马射线分布之间存在明显的空间相关性。在这些高能下检测到的来自体模中核反应的中子数量很少。最重要的是，结果表明在常见的治疗条件下，在一个点扫描步（约 10ms）中可以收集到足够的数据，以 1σ 精度优于 1mm 的准确度定位远端剂量边缘。这表明简单的狭缝相机具有精确实时粒子治疗调整的巨大潜力，并可能成为提高粒子治疗精度的一种实用方法。
