Automated Cephalometry: System Performance Reliability Using Landmark-Dependent Criteria

Objective: The purpose of the present study was to evaluate reliability of a system that performs automatic recognition of anatomic landmarks and adjacent structures on lateral cephalograms using land mark-dependent criteria unique to each landmark. Materials and Methods: To evaluate the reliability of the system, the system was used to examine 65 lateral cephalograms. The area of each system-identified anatomic structure surrounding the landmark and the position of each system-identified landmark were compared with norms using confidence ellipses with alpha = .01, which were derived from the scattergrams of 100 estimates obtained according to the method reported by Baumrind and Frantz. When the system-identified area overlapped with the norm area, anatomic structure recognition was considered successful. In addition, when the system-identified point was located within the norm area, landmark identification was considered successful. Based on these judgment criteria, success rates were calculated for all landmarks. Results: The system successfully identified all specified anatomic structures in all the images and determined the positions of the landmarks with a mean success rate of 88% (range, 77%-100%). Conclusion: With the incorporation of the rational assessment criteria provided by confidence ellipses, the proposed system was confirmed to be reliable. (Angle Orthod. 2009;79:1037-1046.)