Development and evaluation of a software for automatic locating of cephalometric landmarks

ABSTRACT

The cephalometric analysis should be done for patients seeking orthognathic surgical treatments to diagnose dentoalveolar relationships properly. Finding a landmark for the analysis must be time consuming and depends on individual experience or errors and further needs more training. The aim of this study was to develop and evaluate a software for automatically locating of the cephalometric landmarks. A software was designed and developed by programmers group using 140 cephalometric radiographs as databases. Further to cephalograms were grabbed by a digital camera [Sony cybershot 1000X1200] in JPEG format and displayed on LCD monitor [Toshiba, 1600X1200 UXGA] for three expert orthodontists and asked them to locate 10 landmarks. The statistic analysis was based on Paired t test. The results showed 51% of the assigned points by software locating were within 1mm accuracy, 63% within 2 mm and 92% within 4mm accuracy. The mean distance from reference [the mean distance of three observers'points] of seven out often points was less than maximum difference between observers. For B point the mean distance difference in computer locating [0.4mm] was less than mean distance observers' points [3.1mm]. For S point the mean distance difference from reference point was 3.4mm in computer locating which was greater than the mean distance difference between observers [0.6mm]. The study showed that landmark locating errors by computer were not greater than errors of individuals so, perhaps, computer could be a proper substitute for individuals for locating and analysis of cephalometric landmarks