一种逐线加权滤波反投影算法。
A filtered backprojection algorithm with ray-by-ray noise weighting.
机构信息
Utah Center for Advanced Imaging Research (UCAIR), Department of Radiology, University of Utah, Salt Lake City, Utah 84108, USA.
出版信息
Med Phys. 2013 Mar;40(3):031113. doi: 10.1118/1.4790696.
PURPOSE
This paper derives a ray-by-ray weighted filtered backprojection (rFBP) algorithm, based on our recently developed view-by-view weighted, filtered backprojection (vFBP) algorithm.
METHODS
The rFBP algorithm directly extends the vFBP algorithm by letting the noise weighting vary from channel to channel within each view. The projection data can be weighted in inverse proportion to their noise variances. Also, an edge-preserving bilateral filter is suggested to perform post filtering to further reduce the noise. The proposed algorithm has been implemented for the circular-orbit cone-beam geometry based on Feldkamp's algorithm.
RESULTS
Image reconstructions with computer simulations and clinical cadaver data are presented to illustrate the effectiveness and feasibility of the proposed algorithm. The new FBP-type algorithm is able to significantly reduce or remove the noise texture, which the conventional FBP is unable to do. The computation time of the proposed rFBP algorithm is approximately the same as the conventional FBP algorithm.
CONCLUSIONS
A ray-based noise-weighting scheme is introduced to the FBP algorithm. This new FBP-type algorithm significantly reduces or removes the streaking artifacts in low-dose CT.
目的
本文基于我们最近开发的逐视图加权、滤波反投影（vFBP）算法，推导出了一种逐射线加权滤波反投影（rFBP）算法。
方法
rFBP 算法通过让每个视图内的每个通道的噪声权重从通道到通道变化，直接扩展 vFBP 算法。可以按其噪声方差的倒数对投影数据进行加权。此外，还建议使用边缘保持双边滤波器进行后滤波，以进一步降低噪声。该算法已经基于 Feldkamp 算法实现了用于圆形轨道锥束几何结构的。
结果
通过计算机模拟和临床尸体数据的图像重建，说明了所提出算法的有效性和可行性。与传统的 FBP 相比，新的 FBP 类型算法能够显著降低或消除噪声纹理。所提出的 rFBP 算法的计算时间与传统的 FBP 算法大致相同。
结论
将基于射线的噪声加权方案引入 FBP 算法。这种新的 FBP 类型算法显著降低或消除了低剂量 CT 中的条纹伪影。
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