Cephalometric digitization: A determination of the minimum scanner settings necessary for precise landmark identification.

This study focused on the interpretation of scanned cephalometric images after the digitization of the original analog film, with a variety of standard scanner settings. The purpose was to determine the minimum allowable resolution, grayscale, and color settings of these digital images, without compromising the precision of orthodontic landmark identification. Forty-nine orthodontic residents and faculty at Saint Louis University identified 13 landmarks in 3 separate trials on either an original lateral cephalogram or 1 of 6 digitized radiographic images. They also subjectively assessed the quality of the image. Ability to identify landmarks did not differ significantly among the groups tested. Conversely, opinions of image quality differed significantly among the groups. Participants found the quality of the grayscale images without color to be poorer than that of the original film but could detect differences only at resolution extremes. Prediction of ability to identify landmarks was substantially greater for higher resolution images. In conclusion, the scanner settings used in the digitization of a cephalometric film did not matter significantly when standard settings were used. In addition, subjective opinion of image quality was predictive of how precisely landmarks were identified when the resolution was relatively high.