Digitizing of radiographs with a roller-type CCD scanner.

OBJECTIVES

Roller-type scanners can be used to digitize radiographs. This study evaluated the physical performance of a roller-type scanner with regard to dynamic range, scan reproducibility, and homogeneity.

METHODS

A VXR-12 (Vidar System Corp., Herndon, Va.) roller-type scanner with imaging editing software Paint Shop Pro (JASC Inc., Minnetonka, Minn.) was used to digitize a step tablet image on Kodak T-MAT G films (Kodak, Rochester, N.Y.). The step tablet image was scanned at various locations and with different scanning settings. The pixel values of the resulting image were analyzed. The step tablet image was also scanned by a Wellhofer WD 102 Filmdensitometer (Wellhofer Dosimetrie, Schwarzenbruck, Germany) to measure the optical densities of the steps on the film for comparison.

RESULTS

With the use of the default scanning settings the digitized images had pixel values distributed in a similar dynamic range to that of the film densitometer. This scanner produced consistent images with different scanning positions, different orientation of the images, and different power states of the scanner.

CONCLUSIONS

This roller-type scanner has a similar dynamic range to that of the film densitometer. The operating condition of the scanner is stable, and the resulting image is not significantly affected by the scanning positions. This type of scanner should be suitable for digitizing dental x-ray films, although the limiting scanning resolution might not be sufficient for some diagnostic purposes.