A prototype coded aperture detector for small animal SPECT
A prototype coded aperture detector for small animal SPECT
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DOI：
10.1109/tns.2002.803802
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发表时间：
2002-10-01
影响因子：
1.8
通讯作者：
Fulham, MJ
中科院分区：
文献类型：
--
作者：
Meikle, SR;Kench, P;Fulham, MJ
在以前的模拟研究中，我们证明了使用编码孔径与像素化探测器的小动物SPECT的可行性。在本文中，我们进一步探索这种方法的潜力与原型探测器和模拟多针孔孔径。我们还研究了由于重叠投影的多路复用的收敛性能，图像信噪比（SNR）和空间分辨率的影响。该探测器由48 x 44的NaI（TI）晶体阵列组成，每个晶体的间距为1.25 mm，每个晶体的尺寸为1 mm x 1 mm x 5 mm。晶体阵列直接耦合到Hamamatsu R3941 8 cm位置敏感光电倍增管。通过对同一物体进行重复SPECT采集来模拟多针孔孔径，其中单个钨针孔平移到孔径平面中的不同位置。图像重建是基于三维射线驱动的投影仪，这是一个扩展的方法描述的单针孔SPECT与位移的旋转中心。使用最大似然期望最大化（ML-EM）算法更新图像估计。与非复用数据相比，复用的效果是降低收敛速度，并将可实现的SNR降低约15%（但结果可能在一小部分时间内实现）。用分辨率体模获得的重建分辨率为1.5 mm半高全宽，复用和非复用数据的分辨率之间没有明显差异。这些结果鼓励我们开发一个原型编码孔径系统的高灵敏度，高分辨率的小动物SPECT。
In a previous simulation study, we demonstrated the feasibility of using coded apertures together with pixelated detectors for small animal SPECT. In this paper, we further explore the potential of this approach with a prototype detector and simulated multipinhole apertures. We also investigated the effect of multiplexing due to overlapped projections on convergence properties, image signal-to-noise ratio (SNR) and spatial resolution. The detector comprises a 48 x 44 array of NaI(TI) crystals, each I mm x I mm x 5 mm on a 1.25-mm pitch. The crystal array is directly coupled to a Hamamatsu R3941 8 cm position sensitive photomultiplier tube. Multipinhole apertures were simulated by performing repeated SPECT acquisitions of the same object with a single tungsten pinhole translated to different positions in the aperture plane. Image reconstruction is based on a three-dimensional ray driven projector which is an extension of a method described for single pinhole SPECT with a displaced center of rotation. Image estimates are updated using the maximum likelihood expectation maximization (ML-EM) algorithm. The effect of multiplexing was to slow convergence and reduce the achievable SNR by approximately 15% compared with nonmultiplexed data (but the result may be achieved in a fraction of the time). The reconstructed resolution obtained with a resolution phantom was 1.5-mm full width at half maximum and there was no appreciable difference between the resolution of multiplexed and nonmultiplexed data. These results encourage us to develop a prototype coded aperture system for high sensitivity, high resolution small animal SPECT.