Cephalometric Analysis Using Digital Radiography Acquired by a Storage Phosphor Imaging System-A Comparison of Reading soft- and hard-copies

Traditional cephalometric analysis is done on a transparent blue film which is called a hard-copy. The aim of this study was to explore differences in cephalometric measurements between monitor displays (i.e., soft-copies) and hard-copies of digital cephalometric images acquired by a storage phosphor (SP) imaging system. Ten digital cephalograms and their conventional counterparts (a hard-copy on a transparent blue film) were obtained using an SP imaging system and a dye-sublimation printer. Twelve orthodontic residents identified 19 cephalometric landmarks on monitor-displayed soft-copies of digital cephalograms with computer-aided methods, as well as on their counterpart hard-copies using conventional methods. To assess differences between measurements obtained from soft- and hard- copies, 27 cephalometric items generated by a computer-aided digital cephalometric analysis system were analyzed to determine the interobserver errors and absolute differences in the measured values. The influence of the level of cephalometric experience of the observer on measurement differences between soft-and hard-copies was also assessed. Overall interobserver errors of 27 commonly used cephalometric measurements were smaller for the soft-copy compared to the hard-copy of SP digital cephalometric images (0.20~1.78 units for soft-copies, and 0.34~2.72 units for hard-copies). Differences in measurements between the soft-and hard-copies were more significant for linear than angular measurements, particularly items referring to the Frankfort horizontal plane. The overall differences were clinically acceptable and not substantially influenced by the cephalometric experience of the observers.