title: Monitoring image guidance system accuracy during spinal surgery with mini-screw fiducials: technical note.
abstract: METHODS
  A technical note.
  
  
  OBJECTIVE
  To describe a technique for measuring accuracy of intraoperative image guidance systems in spine surgery.
  
  
  BACKGROUND
  Image guidance may be of use when performing complex procedures on the spine. However, as the operation progresses and, in particular, once any deformity has been corrected, the image guidance system may become unreliable. In practice, this often results in repeated image acquisitions thus increasing the radiation exposure to the patient.
  
  
  METHODS
  Small titanium, cranio-facial screws were placed on the dorsal aspect of the spine intraoperatively, before the acquisition of images and used as fiducials.
  
  
  RESULTS
  The authors were able to accurately discern the true precision of the image guidance system used with an intraoperative computed tomography scanner, throughout the procedure.
  
  
  CONCLUSIONS
  By using intraoperatively placed mini-screw fiducials, the surgeon may check and quantify the underlying system accuracy both initially and throughout the surgery. In the future, "auto-adjust" functions may be integrated into the computer software to automatically recalibrate the system when a probe is placed into the fiducials without the need for rescanning.
authors.affiliation: Wentworth Spine Clinic, Dalcross Adventist Hospital, Sydney, NSW, Australia. ysergides@hotmail.com
authors.forename: Ioannis G
authors.initials: IG
authors.lastname: Sergides
authors.forename: Davor D
authors.initials: DD
authors.lastname: Saravanja
authors.forename: William R
authors.initials: WR
authors.lastname: Sears
mesh_terms: D001863:Bone Screws / Q000592:standards*; D057918:Fiducial Markers / Q000592:standards* / Q000706:statistics & numerical data; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data