An apparatus and method for optimally positioning a region of interest of a subject for imaging by a CT scanner. The scanner provides a source of one or more X-ray beams, at least one of which is used for acquiring a CT image of the subject, a movable support for the subject, and a controller that controls the X-ray source. To position the region of interest of the subject, the controller operates to illuminate the subject with X-rays to acquire stereo image data for the region of interest and controls the position of the support responsive to the stereo image data.