A surgical navigation system for navigating a region of a patient includes a non-invasive dynamic reference frame and/or fiducial marker, sensor tipped instruments, and isolator circuits. The dynamic reference frame may be repeatably placed on the patient in a precise location for guiding the instruments....http://www.google.ca/patents/US7818044?utm_source=gb-gplus-sharePatent US7818044 - Method and apparatus for surgical navigation
