title: Analysis of surgeon's line of sight using an optical tracking system with a multifaceted marker device.
abstract: OBJECTIVE
  Video-assisted thoracoscopic surgery (VATS) is a widely used technique where operating surgeons alternate between direct vision through minithoracotomy and monitor-aided vision as required. We analyzed surgeons' line of sight to assess their proficiency at using an optical tracking system with a multifaceted marker device.
  
  
  METHODS
  An infrared optical tracking system was developed that is capable of integrating information from a multifaceted marker device and analyzing three-dimensional (3D) dynamic movements including flexion and rotation. Using this system, we analyzed multiple aspects of surgeons' head poses, thereby indirectly identifying their visual line of sight. A multifaceted device comprising 4 surfaces and 4 markers was constructed and attached to surgeons' heads. The surgeons' head motions were tracked using this multifaceted device and videotaped their face while they performed wedge resection. Both data sets were compared.
  
  
  RESULTS
  The system could document 98.5% of surgeons' head motions, with a high correlation (<kappa> = 0.935) between data acquired using the multifaceted device and video analysis. An inverse correlation was observed between tumor size and the monitor-viewing time ratio by surgeons in pulmonary wedge resection (R(2) = 0.728).
  
  
  CONCLUSIONS
  An optical tracking system with a multifaceted device was able to measure 3D dynamic movements of thoracic surgeons. The associated problems of reflection angle and marker shielding were solved. The utility of this device for analyzing surgeons' visual line of sight during VATS was established.
authors.affiliation: Department of General Thoracic Surgery, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tsunezuka
authors.forename: Daishiro
authors.initials: D
authors.lastname: Kato
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Terauchi
authors.forename: Masanori
authors.initials: M
authors.lastname: Shimomura
authors.forename: Kaori
authors.initials: K
authors.lastname: Ichise
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ito
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nishikawa
authors.forename: Junichi
authors.initials: J
authors.lastname: Shimada
mesh_terms: D000368:Aged; D006804:Ergonomics; D005260:Female; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D007259:Infrared Rays; D008175:Lung Neoplasms / Q000601:surgery*; D008297:Male; D009873:Operating Rooms; D055095:Optics and Photonics; D011187:Posture / Q000502:physiology*; D012399:Rotation; D020775:Thoracic Surgery, Video-Assisted / Q000379:methods*; D014743:Videotape Recording