Optimization of the Signal-to-Background Ratio in Prompt Gamma Imaging Using Energy and Shifting Time-of-Flight Discrimination: Experiments With a Scanning Parallel-Slit Collimator
Optimization of the Signal-to-Background Ratio in Prompt Gamma Imaging Using Energy and Shifting Time-of-Flight Discrimination: Experiments With a Scanning Parallel-Slit Collimator
复制标题
使用能量和移动飞行时间辨别来优化瞬发伽玛成像中的信号背景比：扫描平行缝准直器的实验
DOI：
10.1109/trpms.2018.2846612
复制
发表时间：
2018
影响因子：
4.4
通讯作者：
D. Schaart
中科院分区：
文献类型：
--
作者：
P. Cambraia Lopes;P. Crespo;J. Huizenga;D. Schaart
目前，质子治疗中用于体内质子范围监测的瞬发γ（PG）射线成像受到了广泛关注。使用准直器的PG成像受到中子相关背景的影响。我们研究的有效性的背景减少实验，使用扫描平行狭缝PG准直器作为一个简化的模型的multislat PG相机。分析集中在布拉格峰附近的PG强度分布的衰减区域，这是质子射程估计的典型感兴趣的区域。研究了不同能量窗口的背景降低，有和没有考虑到体模内质子速度的移动飞行时间窗口。提出了适用于基于回旋加速器的笔形波束的实用方法。平行狭缝准直器被放置在前面的铈掺杂的硅酸钇镥耦合数字硅光电倍增管阵列，用于测量能量和时间谱与强度分布的提示事件发出的聚甲基丙烯酸甲酯幻影用160 MeV的质子笔束照射。最佳信号背景比约为1.6，与之前使用刀口狭缝准直器获得的结果相似。然而，鉴于本准直器具有更好的分辨率，PG轮廓衰减区域中的斜率噪声比对于本准直器而言高约1.2。
Much attention is currently being paid to imaging prompt gamma (PG) rays for in vivo proton range monitoring in proton therapy. PG imaging using a collimator is affected by neutron-related background. We study the effectiveness of background reduction experimentally, using a scanning parallel-slit PG collimator as a simplified model of a multislat PG camera. The analysis is focused on the falloff region of the PG intensity profile near the Bragg peak, which is the typical region of interest for proton range estimation. Background reduction was studied for different energy windows, with and without a shifting time-of-flight window that takes into account the proton velocity within the phantom. Practical methods are put forward that apply to cyclotron-based pencil beams. The parallel-slit collimator was placed in front of arrays of cerium-doped lutetium yttrium silicate-coupled digital silicon photomultipliers, used to measure energy and time spectra together with intensity profiles of prompt events emitted from a polymethylmethacrylate phantom irradiated with a 160-MeV proton pencil beam. The best signal-to-background ratio of ~1.6 was similar to that obtained previously with a knife-edge-slit collimator. However, the slope-over-noise ratio in the PG-profile falloff region, was ~1.2 higher for the present collimator, given its better resolution.