Digital x-ray images taken before a surgical procedure by a fluoroscopic C-arm imager are displayed by a computer and overlaid with graphical representations of instruments be used in the operating room. The graphical representations are updated in real-time to correspond to movement of the instruments...http://www.google.co.uk/patents/US6470207?utm_source=gb-gplus-sharePatent US6470207 - Navigational guidance via computer-assisted fluoroscopic imaging
