3D forward and back-projection for X-ray CT using separable footprints.
3D forward and back-projection for X-ray CT using separable footprints.
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DOI：
10.1109/tmi.2010.2050898
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发表时间：
2010-11
影响因子：
10.6
通讯作者：
Balter JM
中科院分区：
文献类型：
--
作者：
Long Y;Fessler JA;Balter JM
3D图像重建的迭代方法有可能改善x射线计算机断层扫描（CT）中传统的滤波反投影（FBP）图像质量。然而，三维锥束前后投影的计算负担是x射线CT实际应用迭代方法所面临的最大挑战之一。此外，投影精度对迭代方法也很重要。本文描述了两种新的可分离足迹（SF）投影方法，将体素足迹函数近似为二维可分离函数。由于这些足迹函数的可分离性，计算它们在检测器单元上的积分大大简化，并且可以高效地实现。SF-TR投影仪在横轴方向上使用梯形函数，在轴向上使用矩形函数，而SF-TT投影仪在两个方向上都使用梯形函数。仿真和实验表明，两种投影方法的精度都高于距离驱动（DD）投影方法，这是目前该领域最先进的方法。对于与大锥角相关的光线，SF-TT投影仪比SF-TR投影仪更精确。SF-TR投影仪具有与DD投影仪相似的计算速度，而SF-TT投影仪大约慢两倍。
Iterative methods for 3D image reconstruction have the potential to improve image quality over conventional filtered back projection (FBP) in X-ray computed tomography (CT). However, the computation burden of 3D cone-beam forward and back-projectors is one of the greatest challenges facing practical adoption of iterative methods for X-ray CT. Moreover, projector accuracy is also important for iterative methods. This paper describes two new separable footprint (SF) projector methods that approximate the voxel footprint functions as 2D separable functions. Because of the separability of these footprint functions, calculating their integrals over a detector cell is greatly simplified and can be implemented efficiently. The SF-TR projector uses trapezoid functions in the transaxial direction and rectangular functions in the axial direction, whereas the SF-TT projector uses trapezoid functions in both directions. Simulations and experiments showed that both SF projector methods are more accurate than the distance-driven (DD) projector, which is a current state-of-the-art method in the field. The SF-TT projector is more accurate than the SF-TR projector for rays associated with large cone angles. The SF-TR projector has similar computation speed with the DD projector and the SF-TT projector is about two times slower.