title: Laser-scan-based navigation in cranio-maxillofacial surgery.
abstract: 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.
  
  
  METHODS
  20 patients with tumours, bone malformations or foreign bodies, scheduled for computer-assisted surgery, were involved in the study.
  
  
  METHODS
  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 1.1mm and a standard deviation of 0.3 mm.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Cranio-Maxillofacial Surgery, University of Heidelberg, Heidelberg, Germany. ruediger@marmulla.com
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Marmulla
authors.forename: Stefan
authors.initials: S
authors.lastname: Hassfeld
authors.forename: Tim
authors.initials: T
authors.lastname: Lüth
authors.forename: Joachim
authors.initials: J
authors.lastname: Mühling
mesh_terms: D000465:Algorithms; D019465:Craniofacial Abnormalities / Q000601:surgery; D004581:Electronics / Q000295:instrumentation; D005145:Face; D005147:Facial Bones / Q000601:surgery*; D005547:Foreign Bodies / Q000601:surgery; D006258:Head and Neck Neoplasms / Q000601:surgery; D006696:Holography / Q000295:instrumentation / Q000379:methods; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D007834:Lasers; D008443:Maxillary Sinus / Q000601:surgery; D055095:Optics and Photonics / Q000295:instrumentation; D019047:Phantoms, Imaging; D012867:Skin / Q000473:pathology; D012886:Skull / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods* / Q000458:organization & administration; D014057:Tomography, X-Ray Computed