Contrast perception in digitized panoramic radiographs compared with their film-based origin


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Abstract

Objectives.We sought to compare the visual image quality of film-based and digitized panoramic radiographs through use of a hole-containing test wedge.Study Design.An aluminum wedge containing 100 cells, of which 90 were given shallow holes, was exposed in the film-based Orthophos CD panoramic unit. Two radiographs subjectively exhibiting optimum contrast were selected. Films were digitized with a charge-coupled device flatbed scanner at 300 dpi. Films and digitized images were rated cellwise by 2 similar groups of 50 observers each with respect to spot perception.Results.The mean sensitivity was 0.26 ± 0.09 for film and 0.20 ± 0.07 for digitized images (P = .000), with a pronounced decline in the latter in regions of high background density. The average specificity was 0.93 ± 0.07 for film versus 0.92 ± 0.08 for digitized images (P = 0.213).Conclusion.Film yielded a significantly higher sensitivity, but this absolute difference was actually small compared with that of the digitized images.

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