A passive-marker-based optical system for computer-aided surgery in otorhinolaryngology:: Development and first clinical experiences

Objectives: 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. Study Design: 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.