1. A method comprising: obtaining a projection image of a projection object; pre-processing the projection image to generate a processed projection image; reconstructing the processed projection image to generate a reconstructed image including an artifact; and removing the artifact in the reconstructed image, wherein the artifact includes a detector edge artifact relating to a detector edge, a projection object edge artifact relating to a projection object edge, and a serrated artifact, and wherein removing the artifact in the reconstructed image includes: removing the detector edge artifact; removing the projection object edge artifact; and removing the serrated artifact; the pre-processing the projection image including segmenting the projection image to generate a segmented projection image.