A detector head design for small-animal PET with silicon photomultipliers (SiPM)
A detector head design for small-animal PET with silicon photomultipliers (SiPM)
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DOI：
10.1088/0031-9155/51/5/004
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发表时间：
2006-03-07
影响因子：
3.5
通讯作者：
Mandelkern, MA
中科院分区：
文献类型：
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作者：
Moehrs, S;Del Guerra, A;Mandelkern, MA
小动物 PET 系统现在正在努力实现亚毫米分辨率。当前基于 PSPMT 和精细像素化闪烁体的系统可以提高到更高分辨率，但代价是其他性能参数和快速上升的成本。此外，在此类系统中，交互深度 (DOI) 信息通常难以评估，尽管该信息非常适合减少视差误差，而视差误差通常是此类高分辨率系统的主要误差。在本研究中，我们提出了一种用于具有内在 DOI 信息的小动物 PET 成像系统的高分辨率探测器头。我们的设计不是基于像素化闪烁体，而是基于经典的安格相机原理，即头部由模块化层构成，每个层由连续的闪烁体板组成，通过新型紧凑型硅光电探测器进行观察。该光电探测器是最近开发的硅光电倍增管 (SiPM)，它不仅非常紧凑，还具有许多其他吸引人的特性：低偏置电压下的高增益、出色的单光电子分辨率和快速定时。建议采用面积约为 4 x 4 cm(2) 的探测器头，由上述类型的三个模块化层构成。我们使用蒙特卡罗模拟软件包 Geant4 进行模拟研究。仿真结果用于优化探测器头的几何形状并表征其性能。此外，还研究了命中估计算法，以确定湮灭光子在整个探测器表面上的相互作用位置。由此产生的探测器对 511 keV 光子的效率几乎均匀，接近 70%，固有空间分辨率小于 0.4 毫米半峰全宽 (fwhm)。
Small-animal PET systems are now striving for sub-millimetre resolution. Current systems based upon PSPMTs and finely pixellated scintillators can be pushed to higher resolution, but at the expense of other performance parameters and a rapidly escalating cost. Moreover, depth of interaction (DOI) information is usually difficult to assess in such systems, even though this information is highly desirable to reduce the parallax error, which is often the dominant error for such high-resolution systems. In this study we propose a high-resolution detector head for a small-animal PET imaging system with intrinsic DOI information. Instead of a pixellated scintillator, our design is based upon the classic Anger camera principle, i.e. the head is constructed of modular layers each consisting of a continuous slab of scintillator, viewed by a new type of compact silicon photodetector. The photodetector is the recently developed silicon photomultiplier (SiPM) that as well as being very compact has many other attractive properties: high gain at low bias voltage, excellent single-photoelectron resolution and fast timing. A detector head of about 4 x 4 cm(2) in area is proposed, constructed from three modular layers of the type described above. We perform a simulation study, using the Monte Carlo simulation package Geant4. The simulation results are used to optimize the geometry of the detector head and characterize its performance. Additionally, hit estimation algorithms are studied to determine the interaction position of annihilation photons correctly over the whole detector surface. The resulting detector has a nearly uniform efficiency for 511 keV photons of similar to 70% and an intrinsic spatial resolution of less than similar to 0.4 mm full width at half maximum (fwhm).