title: A passive-marker-based optical system for computer-aided surgery in otorhinolaryngology: development and first clinical experiences.
abstract: OBJECTIVE
  To develop a new type of optical computer-aided surgery (CAS) device that overcomes some of the restrictions of common systems and to examine its accuracy and usability under laboratory and intraoperative conditions.
  
  
  METHODS
  Prospective study using laboratory experiments and intraoperative data collection.
  
  
  METHODS
  An optical CAS system applying passive optical markers for coordinate determination was developed. Laboratory accuracy measurements were obtained on a Plexiglas model with known coordinates of fiducial markers, before and after predefined table movements. Intraoperative accuracy measurements were recorded from 24 patients undergoing endonasal surgery of the paranasal sinuses with two different referencing techniques (fiducial markers and mouthpiece).
  
  
  RESULTS
  The system demonstrated laboratory accuracy to within 0.86 mm (SD = 0.94 mm). After table movements, the accuracy decreased to 1.12 mm (SD = 0.99 mm), 1.05 mm (SD = 0.96 mm), 1.15 mm (SD = 1.04 mm), and 1.54 mm (SD = 1.25 mm), respectively, in four different positions. Intraoperative accuracy was within 1.14 mm (SD = 0.57 mm) (fiducial markers) and 2.66 mm (SD = 1.89 mm) (mouthpiece) (P < .05). One of the main advantages of the new technology was the possibility of using any common instrument or endoscope by adapting a marker array.
  
  
  CONCLUSIONS
  Passive-marker technology has been demonstrated to be useful for optical position determination in computer-aided surgery.
authors.affiliation: Department of Otorhinolaryngology, Mainz University Hospital, Johannes Gutenberg-University, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Klimek
authors.forename: U
authors.initials: U
authors.lastname: Ecke
authors.forename: B
authors.initials: B
authors.lastname: Lübben
authors.forename: J
authors.initials: J
authors.lastname: Witte
authors.forename: W
authors.initials: W
authors.lastname: Mann
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009298:Nasal Polyps / Q000601:surgery; D055095:Optics and Photonics; D013517:Otorhinolaryngologic Surgical Procedures / Q000295:instrumentation / Q000379:methods*; D010256:Paranasal Sinuses / Q000601:surgery*; D012852:Sinusitis / Q000601:surgery; D013813:Therapy, Computer-Assisted