title: Influence of Head Motion on the Accuracy of 3D Reconstruction with Cone-Beam CT: Landmark Identification Errors in Maxillofacial Surface Model.
abstract: OBJECTIVE
  The purpose of this study was to investigate the influence of head motion on the accuracy of three-dimensional (3D) reconstruction with cone-beam computed tomography (CBCT) scan.
  
  
  METHODS
  Fifteen dry skulls were incorporated into a motion controller which simulated four types of head motion during CBCT scan: 2 horizontal rotations (to the right/to the left) and 2 vertical rotations (upward/downward). Each movement was triggered to occur at the start of the scan for 1 second by remote control. Four maxillofacial surface models with head motion and one control surface model without motion were obtained for each skull. Nine landmarks were identified on the five maxillofacial surface models for each skull, and landmark identification errors were compared between the control model and each of the models with head motion.
  
  
  RESULTS
  Rendered surface models with head motion were similar to the control model in appearance; however, the landmark identification errors showed larger values in models with head motion than in the control. In particular, the Porion in the horizontal rotation models presented statistically significant differences (P < .05). Statistically significant difference in the errors between the right and left side landmark was present in the left side rotation which was opposite direction to the scanner rotation (P < .05).
  
  
  CONCLUSIONS
  Patient movement during CBCT scan might cause landmark identification errors on the 3D surface model in relation to the direction of the scanner rotation. Clinicians should take this into consideration to prevent patient movement during CBCT scan, particularly horizontal movement.
authors.affiliation: Department of Orthodontics, School of Dentistry, 4D Dental Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Kyung-Min
authors.initials: KM
authors.lastname: Lee
authors.affiliation: Department of Orthodontics, School of Dentistry, 4D Dental Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Jin-Myoung
authors.initials: JM
authors.lastname: Song
authors.affiliation: Department of Orthodontics, School of Dentistry, 4D Dental Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Jin-Hyoung
authors.initials: JH
authors.lastname: Cho
authors.affiliation: Department of Orthodontics, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Hyeon-Shik
authors.initials: HS
authors.lastname: Hwang
mesh_terms: D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003951:Diagnostic Errors; D005145:Face / Q000000981:diagnostic imaging*; D056973:Four-Dimensional Computed Tomography / Q000379:methods; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional; D008437:Maxilla / Q000000981:diagnostic imaging*; D008954:Models, Biological; D012399:Rotation; D012886:Skull / Q000000981:diagnostic imaging*