title: Referencing of markerless CT data sets with cone beam subvolume including registration markers to ease computer-assisted surgery - a clinical and technical research.
abstract: BACKGROUND
  As a prerequisite in navigation-assisted surgery, a three-dimensional image data set with registration marker is necessary. Often patients are presented, not being aware of facing a computer-assisted surgical intervention (CAS), with an already performed computed tomography (CT) data set without marker. The aim of this study was to evaluate the accuracy of a new method which allows performing CAS by enhancing the initial markerless data set with a marked subvolume gained by cone beam (CBCT) scan.
  
  
  METHODS
  Therefore four registration markers are inserted and afterwards the patient is strongly limited to the field of interest scanned by CBCT scan (marked data set). Superimposed with the initial data set, a data set with reference markers and with full information is obtained. Registration procedure was performed with group A (25 patients, superimposed marked CBCT scan) and group B (25 patients, initially marked CT scan) using BrainLab® navigation by two observers and overall system accuracy was measured using the registration landmarks and additional intraoperative landmarks (tooth cusps).
  
  
  RESULTS
  Adequate image quality assumed, no significant difference between group A and B was detected. Enhancing an initially performed data set with registration marker by using a marked subvolume could improve the workflow for navigation-assisted surgery due to the availability of cone beam scan technology, provide excellent resolution with reduced metal artifacts nearby dental restorations, and reduce radiation dose for the patient.
  
  
  CONCLUSIONS
  Regarding the advantages of the new method which allows performing CAS by enhancing the initial markerless data set with a marked subvolume gained by cone beam (CBCT) scan, this technique will play a major part in navigation-assisted surgery and will address widespread general methodological solutions that are of great interest in multidisciplinary treatment.
authors: Department of Craniomaxillofacial Surgery, Hannover Medical School, Hannover, Germany.
authors: Harald
authors: H
authors: Essig
authors: Majeed
authors: M
authors: Rana
authors: Horst
authors: H
authors: Kokemueller
authors: Christoph
authors: C
authors: Zizelmann
authors: Constantin
authors: C
authors: von See
authors: Martin
authors: M
authors: Ruecker
authors: Frank
authors: F
authors: Tavassol
authors: Nils-Claudius
authors: NC
authors: Gellrich
mesh_terms: D054893:Cone-Beam Computed Tomography / Q000706:statistics & numerical data*; D019465:Craniofacial Abnormalities / Q000000981:diagnostic imaging / Q000601:surgery; D016208:Databases, Factual / Q000706:statistics & numerical data; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000706:statistics & numerical data*; D009917:Orbital Fractures / Q000000981:diagnostic imaging / Q000601:surgery; D056948:Orthognathic Surgical Procedures / Q000706:statistics & numerical data; D019651:Plastic Surgery Procedures / Q000706:statistics & numerical data; D012371:Robotics; D025321:Surgery, Computer-Assisted / Q000706:statistics & numerical data*