1. A method for reconstructing an image of a subject with an x-ray computed tomography (CT) system, the steps of the method comprising: a) acquiring, with the CT system, image data from the subject; b) reconstructing a plurality of images from the acquired image data, the plurality of images corresponding to a respective plurality of image slices; c) calculating a plurality of weightings from the reconstructed plurality of images; d) producing weighted image data by applying the calculated plurality of weightings to the acquired image data such that the acquired image data is filtered along a direction orthogonal to an orientation of the plurality of image slices; e) reconstructing a prior image from the weighted image data; f) selecting an estimate image of the subject g) producing a sparsified image of the subject using the prior image and the estimate image; and h) reconstructing a desired image of the subject using the sparsified image, the estimate image, and the acquired image data.