The application and accuracy of feature matching on automated cephalometric superimposition

BACKGROUND: The aim of this study was to establish a computer-aided automated method for cephalometric superimposition and to evaluate the accuracy of this method based on free-hand tracing. METHODS: Twenty-eight pairs of pre-treatment (T(1)) and post-treatment (T(2)) cephalograms were selected. Structural superimpositions of the anterior cranial base, maxilla and mandible were independently completed by three operators performing traditional hand tracing methods and by computerized automation using the feature matching algorithm. To quantitatively evaluate the differences between the two methods, the hand superimposed patterns were digitized. After automated and hand superimposition of T(2) cephalograms to T(1) cephalometric templates, landmark distances between paired automated and hand T(2) cephalometric landmarks were measured. Differences in hand superimposition among the operators were also calculated. RESULTS: The T(2) landmark differences in hand tracing between the operators ranged from 0.61 mm to 1.65 mm for the three types of superimposition. There were no significant differences in accuracy between hand and automated superimposition (p > 0.05). CONCLUSIONS: Computer-aided cephalometric superimposition provides comparably accurate results to those of traditional hand tracing and will provide a powerful tool for academic research.