扇束CT极坐标反投影重建算法的对称优化

Symmetry optimization of polar coordinate back-projection reconstruction algorithm for fan beam CT

为了提高扇束滤波反投影(FBP)算法重建图像的速度,提出一种极坐标反投影算法的优化快速重建方法。算法利用三角函数对称性对多幅预处理后的投影数据同时进行极坐标反投影运算;在反投影数据坐标转换时运用像素位置参数的对称性,以减少双线性插值的计算量。实验结果表明,在不牺牲重建图像质量前提下,与传统卷积反投影重建算法相比,优化算法的重建速度提高8倍以上。该优化方法也适应于三维锥束重建,并可推广到多层螺旋三维重建。

To improve the speed of image reconstruction based on fan-beam Filtered Back Projection （ FBP）, a new optimized fast reconstruction method was proposed for polar back-projection algorithm. According to the symmetry feature of trigonometric function, the preprocessing projection datum were back-projected on the polar coordinates at the same time. During the back-projection data coordinate transformation, the computation of bilinear interpolation could be reduced by using the symmetry of the pixel position parameters. The experimental result shows that, compared with the traditional convolution back-projection algorithm, the speed of reconstruction can be improved more than eight times by the proposed method without sacrificing image quality. The new method is also applicable to 3D cone-beam reconstruction, and can be extended to muhilayer spiral three-dimensional reconstruction.