title: A novel augmented reality system of image projection for image-guided neurosurgery.
abstract: BACKGROUND
  Augmented reality systems combine virtual images with a real environment.
  
  
  OBJECTIVE
  To design and develop an augmented reality system for image-guided surgery of brain tumors using image projection.
  
  
  METHODS
  A virtual image was created in two ways: (1) MRI-based 3D model of the head matched with the segmented lesion of a patient using MRIcro software (version 1.4, freeware, Chris Rorden) and (2) Digital photograph based model in which the tumor region was drawn using image-editing software. The real environment was simulated with a head phantom. For direct projection of the virtual image to the head phantom, a commercially available video projector (PicoPix 1020, Philips) was used. The position and size of the virtual image was adjusted manually for registration, which was performed using anatomical landmarks and fiducial markers position.
  
  
  RESULTS
  An augmented reality system for image-guided neurosurgery using direct image projection has been designed successfully and implemented in first evaluation with promising results. The virtual image could be projected to the head phantom and was registered manually. Accurate registration (mean projection error: 0.3 mm) was performed using anatomical landmarks and fiducial markers position.
  
  
  CONCLUSIONS
  The direct projection of a virtual image to the patients head, skull, or brain surface in real time is an augmented reality system that can be used for image-guided neurosurgery. In this paper, the first evaluation of the system is presented. The encouraging first visualization results indicate that the presented augmented reality system might be an important enhancement of image-guided neurosurgery.
authors.affiliation: Department of Neurosurgery, Clinic of Cologne-Merheim, University of Witten-Herdecke, Ostmerheimer Strasse 200, 51109, Köln, Germany. mmahvash@yahoo.de
authors.forename: Mehran
authors.initials: M
authors.lastname: Mahvash
authors.forename: Leila
authors.initials: L
authors.lastname: Besharati Tabrizi
mesh_terms: D006257:Head / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D009493:Neurosurgery / Q000295:instrumentation / Q000379:methods; D019047:Phantoms, Imaging; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D014584:User-Computer Interface; D014741:Video Recording