title: Optimization of radiation exposure and image quality of the cone-beam O-arm intraoperative imaging system in spinal surgery.
abstract: METHODS
  Retrospective study.
  
  
  OBJECTIVE
  To optimize the radiation doses and image quality for the cone-beam O-arm surgical imaging system in spinal surgery.
  
  
  BACKGROUND
  Neurovascular compromise has been reported after screw misplacement during thoracic pedicle screw insertion. The use of O-arm with or without navigation system during spinal surgery has been shown to lower the rate of screw misplacement. The main drawback of such imaging surgical systems is the high radiation exposure.
  
  
  METHODS
  Chest phantom and cadaveric pig spine were examined on the O-arm with different scan settings: 2 were recommended by the O-arm manufacturer (120 kV/320 mAs, and 120 kV/128 mAs), and 3 low-dose settings (80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs). The radiation doses were estimated by Monte Carlo calculations. Objective evaluation of image quality included interobserver agreement in the measurement of pedicular width in chest phantom and assessment of screw placement in cadaveric pig spine.
  
  
  RESULTS
  The effective dose/cm for 120 kV/320 mAs scan was 13, 26, and 69 times higher than those delivered with 80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs scans, respectively. Images with 60 kV/40 mAs were unreliable. Images with 80 kV/80 mAs were considered reliable with good interobserver agreement when measuring the pedicular width (random error 0.38 mm and intraclass correlation coefficient 0.979) and almost perfect agreement when evaluating the screw placement (κ value 0.86).
  
  
  CONCLUSIONS
  The radiation doses of the O-arm system can be reduced 5 to 13 times without negative impact on image quality with regard to information required for spinal surgery.
authors.affiliation: Faculty of Medicine, Lund University, Division of Neuroradiology, Diagnostic Centre for Imaging and Functional Medicine, Skåne University Hospital, Malmö, Sweden. kasim.abul-kasim@med.lu.se
authors.forename: Kasim
authors.initials: K
authors.lastname: Abul-Kasim
authors.forename: Marcus
authors.initials: M
authors.lastname: Söderberg
authors.forename: Eufrozina
authors.initials: E
authors.lastname: Selariu
authors.forename: Mikael
authors.initials: M
authors.lastname: Gunnarsson
authors.forename: Mehrsa
authors.initials: M
authors.lastname: Kherad
authors.forename: Acke
authors.initials: A
authors.lastname: Ohlin
mesh_terms: D000328:Adult; D000818:Animals; D001863:Bone Screws / Q000592:standards; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D016343:Monitoring, Intraoperative / Q000379:methods*; D019047:Phantoms, Imaging / Q000592:standards; D011829:Radiation Dosage; D012189:Retrospective Studies; D013131:Spine / Q000000981:diagnostic imaging / Q000601:surgery; D013552:Swine