Apparatus for reduction of filtration truncation errors

摘要

Apparatus for reduction of filtration truncation errors caused by convolving a plurality of input signals, such as line-integral projection data obtained in a computerized tomography (CT) scan of an object, with a common kernel function in a finite precision machine using Fourier transform techniques. The resulting convolved output signals contain correlated noise which, in the case of reconstructed CT images, manifests itself as structured noise in the form of rings and center spots in the image. The correlated noise can be reduced by randomly shifting the data prior to convolving it. The random shift can be achieved by a rotational permutation scheme. Another scheme for shifting the data is to prepend or append zeros to the data by using a random number generator or a deterministic function.