1. A tomographic system comprising: a gantry having an opening for receiving an object to be scanned; a radiation source; a detector positioned to receive radiation from the source that passes through the object; and a computer programmed to: acquire a short scan angular range of data of the object, the short scan angular range of data comprising data acquired during a single cardiac cycle and rotation of the detector about the object; define a temporal subset of the acquired short scan angular range of data for image reconstruction, the defined temporal subset of the acquired short scan angular range of data comprising approximately half of the angular range of the short scan angular range of data; reconstruct a prior image using the acquired short scan angular range of data; and input an estimated image of the object and the prior image into an objective function and minimize the objective function to reconstruct a refined image using the defined temporal subset of scan data and the prior image.