Rotate-and-slant projector for fast LOR-based fully-3-D iterative PET reconstruction.
Rotate-and-slant projector for fast LOR-based fully-3-D iterative PET reconstruction.
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DOI：
10.1109/tmi.2008.918328
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发表时间：
2008-08
影响因子：
10.6
通讯作者：
Kadrmas DJ
中科院分区：
文献类型：
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作者：
Kadrmas DJ
迭代全 3D 正电子发射断层扫描 (PET) 重建面临的最大挑战之一是重建时间长的问题，因为与 2D 模式相比，3D 模式需要大量测量。已经开发出一种旋转倾斜投影仪，它利用几何对称性以计算有效的方式计算多个倾斜正弦图的体积投影。它基于使用三遍剪切方法的基于 2D 旋转的投影仪，并且它保留了对每个倾斜正弦图集进行多次投影的 2D 旋转器计算。该投影仪同样适用于传统的均匀间隔投影和不均匀间隔响应线 (LOR) 数据。基于 LOR 的版本对各个 LOR 的位置和方向进行建模（即弧校正），提供普通的泊松重建框架。该投影仪是用 C 语言实现的，对速度进行了多项优化，利用了倾斜投影过程的垂直对称性、深度压缩和最大化串行内存访问的数组索引方案。使用分析和实验模型对新投影仪进行了评估，并将其与光线驱动和距离驱动投影仪进行了比较，并将每个投影仪的全 3-D 迭代重建与傅里叶重新组合与 2-D 迭代重建进行了比较。在空间分辨率、对比度和背景噪声测量方面，使用旋转倾斜投影仪进行的基于 3-D LOR 的迭代重建与其他方法一样好，甚至更好。在单 CPU Linux 工作站上测得的总处理时间，旋转倾斜投影仪比研究的其他 3D 投影仪快约 10 倍。新投影仪在短短 15 秒内提供了四次迭代全 3-D 有序子集重建，与 FORE + 2-D 重建的时间大致相同。我们得出的结论是，旋转倾斜投影仪是全 3D PET 的可行选择，提供高质量的统计重建，速度仅比 2D 或重组方法稍慢。
One of the greatest challenges facing iterative fully-3-D positron emission tomography (PET) reconstruction is the issue of long reconstruction times due to the large number of measurements for 3-D mode as compared to 2-D mode. A rotate-and-slant projector has been developed that takes advantage of symmetries in the geometry to compute volumetric projections to multiple oblique sinograms in a computationally efficient manner. It is based upon the 2-D rotation-based projector using the three-pass method of shears, and it conserves the 2-D rotator computations for multiple projections to each oblique sinogram set. The projector is equally applicable to both conventional evenly-spaced projections and unevenly-spaced line-of-response (LOR) data. The LOR-based version models the location and orientation of the individual LORs (i.e., the arc-correction), providing an ordinary Poisson reconstruction framework. The projector was implemented in C with several optimizations for speed, exploiting the vertical symmetry of the oblique projection process, depth compression, and array indexing schemes which maximize serial memory access. The new projector was evaluated and compared to ray-driven and distance-driven projectors using both analytical and experimental phantoms, and fully-3-D iterative reconstructions with each projector were also compared to Fourier rebinning with 2-D iterative reconstruction. In terms of spatial resolution, contrast, and background noise measures, 3-D LOR-based iterative reconstruction with the rotate-and-slant projector performed as well as or better than the other methods. Total processing times, measured on a single cpu Linux workstation, were ∼ 10× faster for the rotate-and-slant projector than for he other 3-D projectors studied. The new projector provided four iterations fully-3-D ordered-subsets reconstruction in as little as 15 s—approximately the same time as FORE + 2-D reconstruction. We conclude that the rotate-and-slant projector is a viable option for fully-3-D PET, offering quality statistical reconstruction in times only marginally slower than 2-D or rebinning methods.