FIRST:: Fast Iterative Reconstruction Software for (PET) tomography
FIRST:: Fast Iterative Reconstruction Software for (PET) tomography
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DOI：
10.1088/0031-9155/51/18/007
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发表时间：
2006-09-21
影响因子：
3.5
通讯作者：
Udias, J. M.
中科院分区：
文献类型：
--
作者：
Herraiz, J. L.;Espana, S.;Udias, J. M.
小动物PET扫描仪需要高空间分辨率和良好的灵敏度。为了在3D-PET中重建高分辨率图像，迭代方法（诸如OSEM）比解析重建算法优越上级，尽管它们的高计算成本仍然是一个严重的缺点。现代计算机的更高性能可以使迭代图像重建足够快，是可行的，只要我们能够处理大量的概率系数的系统响应矩阵在高分辨率PET扫描仪，这是一个困难的任务，阻止算法达到峰值计算性能。考虑到所有可能的轴向和面内对称性，以及某些准对称性，我们已经能够将存储系统响应矩阵（SRM）的内存需求降低到1 GB以下，这使我们能够将系统的整个响应矩阵保持在普通工业标准计算机的RAM内，从而使重建算法可以实现接近峰值的性能。SRM的元素被存储为三次样条曲线，并在重建过程中与体素大小相匹配。通过这种方式，结合了“即时”计算和完全存储SRM的优点。SRM计算的实时部分（将轮廓函数与体素大小匹配）占重建时间的10-30%，具体取决于所选体素的数量。我们用商业小动物PET扫描仪的真实的数据测试了我们的方法。结果（图像质量和重建时间）表明，所提出的技术是一种可行的解决方案。
Small animal PET scanners require high spatial resolution and good sensitivity. To reconstruct high-resolution images in 3D-PET, iterative methods, such as OSEM, are superior to analytical reconstruction algorithms, although their high computational cost is still a serious drawback. The higher performance of modern computers could make iterative image reconstruction fast enough to be viable, provided we are able to deal with the large number of probability coefficients for the system response matrix in high-resolution PET scanners, which is a difficult task that prevents the algorithms from reaching peak computing performance. Considering all possible axial and in-plane symmetries, as well as certain quasi-symmetries, we have been able to reduce the memory requirements to store the system response matrix (SRM) well below 1 GB, which allows us to keep the whole response matrix of the system inside RAM of ordinary industry-standard computers, so that the reconstruction algorithm can achieve near peak performance. The elements of the SRM are stored as cubic spline profiles and matched to voxel size during reconstruction. In this way, the advantages of `on-the-fly' calculation and of fully stored SRM are combined. The on-the-fly part of the calculation ( matching the profile functions to voxel size) of the SRM accounts for 10-30% of the reconstruction time, depending on the number of voxels chosen. We tested our approach with real data from a commercial small animal PET scanner. The results ( image quality and reconstruction time) show that the proposed technique is a feasible solution.