A system includes acquisition of a first image of a portion of a body, the
first image representing the portion during a first phase of motion,
acquisition of a second image of the portion of the body, the second
image representing the portion during a second phase of motion,
generation of a composite image based on the first image and the second
image, the composite image indicating a position of a target during the
first phase of motion and a position of the target during the second
phase of motion, and identification of a target region based on the
composite image.