A parallel backprojection algorithm for spiral cone-beam ct exact reconstruction

On reconstructing a volume, the exact reconstruction algorithm for spiral cone-beam CT accesses the memory many times while all the filtered projection data has to be arrived. This is quite a bottleneck for implementation. Normally, the filtered projection data is transferred frame by frame in serial. In this paper, a new backprojection algorithm is proposed. The algorithm uses data inside the Tam-Danielsson window and slightly more. When one filtered projection pixel data arrives, certain interpolation algorithm is used on the data and the dedicated volume is decided by the coordinate of the pixel data. Then the dedicated volume is updated by the interpolated data. The procedure repeats when the next filtered backprojection arrives. If the transfer rate is slow enough, then the real-time backprojection can be achieved. Experiment results are given. It can been seen that the image quality is satisfactory and the artifact is greatly refined.