1. A method for reconstructing an image using a tomographic imaging system, said method comprising: generating a first estimate of the image; generating a second estimate of the image after generating the first estimate of the image; comparing actual projection data and expected projection data of the second estimate of the image; adjusting the first estimate using the comparison; generating a virtual X-ray source corresponding to a real X-ray source of the tomographic imaging system; generating a virtual X-ray detector plane including a plurality of virtual detector elements corresponding to a real X-ray detector array of the tomographic imaging system, the real X-ray detector array including a plurality of detector cells to which the plurality of virtual detector elements correspond; determining image volume data that includes a value representing an X-ray density of an image voxel using the virtual X-ray source and the virtual X-ray detector; assigning a first weight to a first portion of the actual projection data and a first forward projection function, wherein the first portion of the actual projection data and the first forward projection function are generated when the virtual X-ray source is at a first position and are used to reconstruct the image voxel; assigning a second weight to a second portion of the actual projection data and a second forward projection function, wherein the second portion of the actual projection data and the second forward projection function are generated when the virtual X-ray source is at a second position and are used to reconstruct the image voxel, the second weight being lower than the first weight, and the first position being closer to the image voxel than the second position is to the image voxel; adjusting the first estimate using the image volume data; and outputting the image based on the adjusted first estimate of the image, the output image having a higher resolution than a resolution of the first estimate.