FAST HIERARCHICAL BACKPROJECTION METHOD FOR IMAGING

摘要

A process for backprojecting a sinogram (10) to a tomographic image (12) includes the steps of subdividing the sinogram (10) into a plurality of subsinograms (14, 16, 18, 20), preferably in a recursive manner, until each subsinogram (14, 16, 18, 20) represents an image as small as one pixel in size. Each of the final subsinograms (14, 16, 18, 20) is backprojected to produce a plurality of corresponding subimages (22, 24, 26, 28), and the subimages (22, 24, 26, 28) are aggregated to create the image. Two algorithms can be used in the decomposition process. An exact decomposition algorithm is accurate, but relatively slow. An approximation decomposition algorithm is less accurate, but fast. By switching between the two algorithms, accurate decomposition is realized in a short time, speeding up the backprojection process considerably.