title: Optimization analysis for plane orientation in 3-dimensional cephalometric analysis of serial cone-beam computerized tomography images.
abstract: OBJECTIVE
  The purpose of this study was to evaluate and reduce potential errors associated with superimposition of serial cone-beam computerized tomography (CBCT) images using planes based on cranial base landmarks.
  
  
  METHODS
  CBCTs from 10 patients were analyzed. The potential impact of errors in cranial base landmark identification on assessment of the relative position of distant landmarks is mitigated by means of a mathematical algorithm that ensures that the distances and angles between landmark identification points are maintained for different images by readjusting the landmark coordinates.
  
  
  RESULTS
  Significant improvement was observed after optimization. The errors found in a previous study were significantly reduced, some by more than 90%. Errors found in the standardization were viewed in both infraorbitals and mentons ranging from 1 to 3 mm.
  
  
  CONCLUSIONS
  The mathematical transformation to readjust the coordinates of ELSA, left and right auditory external meatus (AEM), and dorsum foramen magnum (DFM) points significantly improves their use for image superimposition.
authors.affiliation: Faculty of Medicine and Dentistry, University of Alberta, Alberta, Canada. manuel@ualberta.ca
authors.forename: Manuel O
authors.initials: MO
authors.lastname: Lagravère
authors.forename: Marc
authors.initials: M
authors.lastname: Secanell
authors.forename: Paul W
authors.initials: PW
authors.lastname: Major
authors.forename: Jason P
authors.initials: JP
authors.lastname: Carey
mesh_terms: D000465:Algorithms; D002508:Cephalometry / Q000295:instrumentation / Q000379:methods*; D003198:Computer Simulation; D054893:Cone-Beam Computed Tomography; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods*; D008953:Models, Anatomic; D019291:Skull Base / Q000033:anatomy & histology* / Q000000981:diagnostic imaging