On intermediate view estimation in computed tomography

In many applications in computed tomography, practical limitations in data acquisition restrict the number of projections (views). The use of the stan dard convolution backprojection algorithm for reconstruction from an inadeq uate number of projections results in view aliasing artifacts. One approach to alleviating the effects of such artifacts consists of artificially incr easing the number of views, by estimating a set of intermediate views. Two possible methods of estimating the intermediate views are interpolation and reprojection. In this paper, a study of the two is considered. Based on th e merits and demerits of the two methods, a combination of the two methods is investigated. Specifically, a reconstruction from the available sinogram augmented by intermediate view reprojections, and the projections interpol ated from the original views and the reprojections, provide an additional i mprovement with respect to view aliasing artifacts. The advantage of comput ing reprojections over smaller regions of interest is discussed. When the n umber of available projections is reasonably high but not adequate to produ ce an artifact-free reconstruction, estimating the intermediate views by in terpolation provides an improvement without much additional degradation, at minimal computational cost.