1. A method of self-gating a set of images, the method comprising: acquiring a set of overlapping slice images of a patient's heart; generating a projection with the set of slice images; marking a region of the projection; analyzing the marked region to calculate a heart frequency and phase of the patient's heart motion; selecting groups of slice images from the set of slice images, based on their relative position in the calculated heart motion frequency and phase; and generating a plurality of groups of slices that correspond to different phases of heart motion.