Comparison of measurements from conventional, scanned, and photographed lateral cephalograms: An in vitro study

Background: The cephalograms are invaluable in diagnosis, treatment planning, and evaluation of treatment results. Digital cephalograms have several advantages. Conventional cephalograms can be converted to digital format by scanning on a flatbed scanner. More recently it was reported that conventional cephalograms photographed with a digital camera can be used for doing cephalometric analysis. However, the accuracy of the measurements is not very clear. Aim: To compare the accuracy of angular and linear measurements obtained from scanned and photographed images of conventional cephalograms with that of manually traced original cephalograms. Materials and Methods: Twenty cephalograms of patients taken in natural head position (NHP) were converted to digital format by scanning on a flatbed scanner and also were photographed with a high resolution digital camera. Both images were digitized with Vista Dent OC Imaging TM cephalometric software. Customized cephalometric analysis was performed on both images, and the measurements were recorded. Results: Statistical analysis was done using paired Student's t -test and intraclass correlation coefficient tests. The results showed that; 1. There was significant distortion when analog cephalograms were converted to digital format by photographing. 2. Scanned images were more comparable to the original cephalograms than photographed images. 3. Among the linear and angular measurements, linear measurements showed significant variation than angular measurements. Conclusion: It is acceptable to use digital photographs of cephalograms if angular measurements are primarily required. However, these images might not be acceptable if linear measurements are needed.