A radiography system includes an imaging controller, a reconstruction processor, a process sequence controller and a display section. The imaging controller controls a radiation source to move in a range of a designated sweep angle and project X-rays at different angles to an imaging subject, while controlling a flat panel detector to acquire a set of projection images. The reconstruction processor uses the set of projection images to produce a plurality of tomographic images for use in diagnosis. The process sequence controller determines a parameter for sorting the plurality of tomographic images into first and second groups according to the sweep angle of the radiation source so as the first group of tomographic images to be produced prior to the second group of tomographic images. The display section displays at least the first group of tomographic images.