Design and simulation of a high-resolution stationary SPECT system for small animals
Design and simulation of a high-resolution stationary SPECT system for small animals
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DOI：
10.1088/0031-9155/49/19/009
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发表时间：
2004-10-07
影响因子：
3.5
通讯作者：
Vastenhouw, B
中科院分区：
文献类型：
--
作者：
Beekman, FJ;Vastenhouw, B
通过将针孔成像与紧凑型高分辨率伽马相机相结合，可以创建令人兴奋的新SPECT系统。这些新系统能够解决阻碍当代小动物SPECT的有限灵敏度-分辨率权衡的问题。这里介绍的设计（U-SPECT-III）使用一组放置在多边形配置和圆柱形准直器，其中包含135个针孔排列在九个环的探测器。每个环包含15个黄金针孔孔，集中在圆柱体的中心。通过每个针孔采集非重叠投影。因此，当小鼠大脑被放置在中央视野中时，大脑中的每个体素可以通过130到135个不同的针孔同时观察。描述了一种用于高分辨率闪烁检测的方法，其消除了针孔相机遇到的相互作用深度问题，并且预期提供优于150 μ m的固有检测器分辨率。通过模拟，U-SPECT-III与具有由2.0 x 2.0 mm NaI晶体组成的像素化阵列的模拟双针孔SPECT（DP-SPECT）系统进行了比较。分析计算表明，当在匹配系统灵敏度下比较系统时，所提出的U-SPECT-III系统产生比DP-SPECT高近四倍的线性和高约六十倍的体积系统分辨率。此外，当系统在相同分辨率下进行比较时，U-SPECT-III的灵敏度应该可以高出15至30倍。数字小鼠脑体模的模拟图像显示U-SPECT-III比DP-SPECT更详细。在分辨率体模中，0.3 mm直径的冷棒在U-SPECT-III中清晰可见，而在DP-SPECT中最小的可见棒约为0.6-0.8 mm。此外，在U-SPECT-III中，在重建的中心平面外的图像变形（妨碍常规针孔SPECT）被强烈抑制。模拟结果表明，未来的针孔SPECT系统可能会显着改善小动物的放射分子成像。
Exciting new SPECT systems can be created by combining pinhole imaging with compact high-resolution gamma cameras. These new systems are able to solve the problem of the limited sensitivity-resolution trade-off that hampers contemporary small animal SPECT. The design presented here (U-SPECT-III) uses a set of detectors placed in a polygonal configuration and a cylindrical collimator that contains 135 pinholes arranged in nine rings. Each ring contains 15 gold pinhole apertures that focus on the centre of the cylinder. A non-overlapping projection is acquired via each pinhole. Consequently, when a mouse brain is placed in the central field-of-view, each voxel in the cerebrum can be observed via 130 to 135 different pinholes simultaneously. A method for high-resolution scintillation detection is described that eliminates the depth-of-interaction problem encountered with pinhole cameras, and is expected to provide intrinsic detector resolutions better than 150 mum. By means of simulations U-SPECT-III is compared to a simulated dual pinhole SPECT (DP-SPECT) system with a pixelated array consisting of 2.0 x 2.0 mm NaI crystals. Analytic calculations indicate that the proposed U-SPECT-III system yields an almost four times higher linear and about sixty times higher volumetric system resolution than DP-SPECT, when the systems are compared at matching system sensitivity. In addition, it should be possible to achieve a 15 up to 30 times higher sensitivity with U-SPECT-III when the systems are compared at equal resolution. Simulated images of a digital mouse-brain phantom show much more detail with U-SPECT-III than with DP-SPECT. In a resolution phantom, 0.3 mm diameter cold rods are clearly visible with U-SPECT-III, whereas with DP-SPECT the smallest visible rods are about 0.6-0.8 mm. Furthen-nore, with U-SPECT-III, the image deformations outside the central plane of reconstruction that hamper conventional pinhole SPECT are strongly suppressed. Simulation results indicate that future pinhole SPECT systems are likely to bring about significant improvements in radio-molecular imaging of small animals.