DigiPET: sub-millimeter spatial resolution small-animal PET imaging using thin monolithic scintillators
DigiPET: sub-millimeter spatial resolution small-animal PET imaging using thin monolithic scintillators
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DOI：
10.1088/0031-9155/59/13/3405
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发表时间：
2014-07-07
影响因子：
3.5
通讯作者：
Van Holen, Roel
中科院分区：
文献类型：
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作者：
Espana, Samuel;Marcinkowski, Radoslaw;Van Holen, Roel
提出了一种新的基于dSiPMs的临床前PET系统，称为DigiPET。该系统基于薄单片闪烁晶体，与基于像素化晶体的系统相比，具有更高的低成本空间分辨率。目前专用的小型啮齿动物PET扫描仪的空间分辨率约为1毫米。它们大多占地面积大，需要相当大的实验室空间。对于啮齿动物的大脑成像，需要一个亚毫米分辨率的PET扫描仪。为了实现这一点，使用了像素间距低至0.5 mm的晶体。然而，精细像素很难产生，并且会使系统变得昂贵。在这项工作中，我们提出了基于薄单片闪烁体和大立体角的高分辨率临床前PET扫描仪的第一个结果。该设计专门用于大鼠脑成像，因此具有非常紧凑的几何结构。四个探测器在两个相对的探测器模块之间以34.5 mm的距离以正方形排列，定义视场（FOV）为32 x 32 x 32 mm(3)。每个探测器由一个32 x 32 x 2 mm3的薄单片LYSO晶体光学耦合到数字硅光电倍增管（dSiPM）组成。利用最大似然估计（MLE）方法获得各检测器内的事件定位。为了评价系统的性能，我们测量了能量分辨率、符合分辨时间（CRT）、灵敏度和空间分辨率。在注射18F-FDG 1小时后，通过获取充满F-18-FDG的热杆模体和大鼠头部来评估图像质量。MLE在探测器上的平均本征空间分辨率为0.54 mm FWHM。我们获得了680 ps的CRT和511 keV下18% FWHM的能量分辨率。视场中心的灵敏度和空间分辨率分别为6.0 cps kBq（-1）和0.7 mm。在热杆幻影的重建图像中，可以分辨出小至0.7 mm的热杆。综上所述，我们利用dSiPM技术和薄单片LYSO晶体构建了一个紧凑的PET扫描仪。具有良好的空间分辨率和可接受的灵敏度。在热杆模型和大鼠脑成像中也获得了令人鼓舞的结果。
A new preclinical PET system based on dSiPMs, called DigiPET, is presented. The system is based on thin monolithic scintillation crystals and exhibits superior spatial resolution at low-cost compared to systems based on pixelated crystals. Current dedicated small-rodent PET scanners have a spatial resolution in the order of 1 mm. Most of them have a large footprint, requiring considerable laboratory space. For rodent brain imaging, a PET scanner with sub-millimeter resolution is desired. To achieve this, crystals with a pixel pitch down to 0.5 mm have been used. However, fine pixels are difficult to produce and will render systems expensive. In this work, we present the first results with a high-resolution preclinical PET scanner based on thin monolithic scintillators and a large solid angle. The design is dedicated to rat-brain imaging and therefore has a very compact geometry. Four detectors were placed in a square arrangement with a distance of 34.5 mm between two opposing detector modules, defining a field of view (FOV) of 32 x 32 x 32 mm(3). Each detector consists of a thin monolithic LYSO crystal of 32 x 32 x 2 mm3 optically coupled to a digital silicon photomultiplier (dSiPM). Event positioning within each detector was obtained using the maximum likelihood estimation (MLE) method. To evaluate the system performance, we measured the energy resolution, coincidence resolving time (CRT), sensitivity and spatial resolution. The image quality was evaluated by acquiring a hot-rod phantom filled with F-18-FDG and a rat head one hour after an 18F-FDG injection. The MLE yielded an average intrinsic spatial resolution on the detector of 0.54 mm FWHM. We obtained a CRT of 680 ps and an energy resolution of 18% FWHM at 511 keV. The sensitivity and spatial resolution obtained at the center of the FOV were 6.0 cps kBq(-1) and 0.7 mm, respectively. In the reconstructed images of the hot-rod phantom, hot rods down to 0.7 mm can be discriminated. In conclusion, a compact PET scanner was built using dSiPM technology and thin monolithic LYSO crystals. Excellent spatial resolution and acceptable sensitivity were demonstrated. Promising results were also obtained in a hot-rod phantom and in rat-brain imaging.