傅里叶重排应用于多平面圆形轨道锥束单光子发射计算机断层扫描。

Department of Biomedical Engineering, The University of North Carolina, Chapel Hill 27599-7575, USA.

IEEE Trans Med Imaging. 1999 Nov;18(11):1076-84. doi: 10.1109/42.816071.

We study the application of Fourier rebinning methods to dual-planar cone-beam SPECT. Dual-planar cone-beam SPECT involves the use of a pair of dissimilar cone-beam collimators on a dual-camera SPECT system. Each collimator has its focus in a different axial plane. While dual-planar data is best reconstructed with fully three-dimensional (3-D) iterative methods, these methods are slow and have prompted a search for faster reconstruction techniques. Fourier rebinning was developed to estimate equivalent parallel projections from 3-D PET data, but it simply expresses a relationship between oblique projections taken in planes not perpendicular to the axis of rotation and direct projections taken in those that are. We find that it is possible to put cone-beam data in this context as well. The rebinned data can then be reconstructed using either filtered backprojection (FBP) or parallel iterative algorithms such as OS-EM. We compare the Feldkamp algorithm and fully 3-D OSEM reconstruction with Fourier-rebinned reconstructions on realistically-simulated Tc-99m HMPAO brain SPECT data. We find that the Fourier-rebinned reconstructions exhibit much less image noise and lower variance in region-of-interest (ROI) estimates than Feldkamp. Also, Fourier-rebinning followed by OSEM with nonuniform attenuation correction exhibits less bias in ROI estimates than Feldkamp with Chang attenuation correction. The Fourier-rebinned ROI estimates exhibit bias and variance comparable to those from fully 3-D OSEM and require considerably less processing time. However, in areas off the axis of rotation, the axial-direction resolution of FORE-reconstructed images is poorer than that of images reconstructed with 3-D OSEM. We conclude that Fourier rebinning is a practical and potentially useful approach to reconstructing data from dual-planar circular-orbit cone-beam systems.

我们研究了傅里叶重排方法在双平面锥束单光子发射计算机断层扫描（SPECT）中的应用。双平面锥束SPECT涉及在双相机SPECT系统上使用一对不同的锥束准直器。每个准直器的焦点位于不同的轴向平面。虽然双平面数据最好用全三维（3-D）迭代方法重建，但这些方法速度较慢，促使人们寻找更快的重建技术。傅里叶重排是为了从3-D正电子发射断层扫描（PET）数据估计等效平行投影而开发的，但它只是表达了在不垂直于旋转轴的平面上获取的斜投影与在垂直于旋转轴的平面上获取的直接投影之间的关系。我们发现也可以将锥束数据置于这种背景下。然后可以使用滤波反投影（FBP）或诸如有序子集期望最大化（OS-EM）等并行迭代算法来重建重排后的数据。我们在真实模拟的Tc-99m六甲基丙烯胺肟（HMPAO）脑SPECT数据上，将费尔德坎普算法和全3-D OSEM重建与傅里叶重排重建进行了比较。我们发现，与费尔德坎普算法相比，傅里叶重排重建的图像噪声要少得多，感兴趣区域（ROI）估计的方差也更低。此外，与采用张衰减校正的费尔德坎普算法相比，傅里叶重排后再进行非均匀衰减校正的OSEM在ROI估计中表现出的偏差更小。傅里叶重排的ROI估计的偏差和方差与全3-D OSEM相当，并且所需的处理时间要少得多。然而，在旋转轴以外的区域，FORE重建图像的轴向分辨率比用3-D OSEM重建的图像要差。我们得出结论，傅里叶重排是一种从双平面圆形轨道锥束系统重建数据的实用且可能有用的方法。