title: Automatic fusion of lateral cephalograms and digital volume tomography data-perspective for combining two modalities in the future.
abstract: OBJECTIVE
  This article investigates the combination of three-dimensional (3D) digital volume tomography data with two-dimensional (2D) cephalograms in dentomaxillofacial imaging.
  
  
  METHODS
  An automatic hierarchical method to adjust the geometrical relations of these two modalities is presented. The approach is tested on phantom and patient case data, where the feasibility, usability and potential possibilities of the presented innovative method are highlighted. Digitally reconstructed radiographs are computed by casting rays through the 3D volume to get a 2D projection of the volume to produce realistic simulated cephalograms. Different similarity measures are considered based on variations of statistical and deterministic optimization procedures. Stability, precision and accuracy of the method are investigated.
  
  
  RESULTS
  The presented algorithm demonstrates a reasonable solution of the corresponding 2D/3D registration problem. Exemplary results from phantom and patient case data are presented. Tooth movement could be determined, in contrast to the 2D lateral cephalogram, separated for each side in all three spatial directions.
  
  
  CONCLUSIONS
  Achieved results are highlighted from a clinical point of view and demonstrate the clinical benefit in daily praxis.
authors.affiliation: 1 Sirona Dental Systems GmbH, Division of Imaging Systems, Innovation Center, Bensheim, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Sauppe
authors.affiliation: 1 Sirona Dental Systems GmbH, Division of Imaging Systems, Innovation Center, Bensheim, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Abkai
authors.affiliation: 2 Department of Orthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Hourfar
authors.affiliation: 3 Private Practice, Traben-Trarbach and Department of Orthodontics, University of Homburg/Saar, Saarland, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Ludwig
authors.affiliation: 1 Sirona Dental Systems GmbH, Division of Imaging Systems, Innovation Center, Bensheim, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Ulrici
authors.affiliation: 1 Sirona Dental Systems GmbH, Division of Imaging Systems, Innovation Center, Bensheim, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Hell
mesh_terms: D000465:Algorithms; D002508:Cephalometry / Q000379:methods*; D003198:Computer Simulation; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003626:Data Display; D005147:Facial Bones / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D019047:Phantoms, Imaging; D012886:Skull / Q000000981:diagnostic imaging; D014087:Tooth Movement Techniques / Q000379:methods; D014584:User-Computer Interface
keywords: 2D/3D registration; DVT; cephalogram; image fusion; multimodality registration