Laser-scan-based navigation in cranio-maxillofacial surgery

Background: In computer-assisted surgery, a correlation between a volume data set and the surgical site is required in order to localize the patient's head on the operating table. Registration markers are commonly used for this procedure. However, the marker registration is associated with high logistics, since the markers have to be placed prior to data set acquisition and have to be kept in their position until the patient enters the operating room. This study deals with a new markerless registration method in cranio-maxillofacial surgery that is based on a high-resolution laser-scan of the patient's (relaxed) skin surface. Patients: 20 patients with tumours, bone malformations or foreign bodies, scheduled for computer-assisted surgery, were involved in the study. Study design: The clinically applied accuracy of the laser-scan-based registration was measured through additionally placed registration markers. The inherent precision of the laser-scan registration system was controlled in phantom studies. Results: The clinically applied accuracy of the new laser-scan-based registration technique ranged between 0.2 and 1.8 mm with a mean deviation of 1.1 mm and a standard deviation of 0.3 mm. Conclusion: The facial skin surface can serve as a sufficiently stable and invariable reference base in order to register patients for computer-assisted cranio-maxillofacial surgery.