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 scann er with imaging editing software Paint Shop Pro (JASC Inc., Minnetonka , Minn.) was used to digitize a step tablet image on Kodak T-MAT G fil ms (Kodak, Rochester, N.Y.). The step tablet image was scanned at vari ous locations and with different scanning settings. The pixel values o f the resulting image were analyzed. The step tablet image was also sc anned by a Wellhofer WD 102 Filmdensitometer (Wellhofer Dosimetrie, Sc hwarzenbruck, Germany) to measure the optical densities of the steps o n the film for comparison. Results. With the use of the default scanni ng settings the digitized images had pixel values distributed in a sim ilar dynamic range to that of the film densitometer. This scanner prod uced consistent images with different scanning positions, different or ientation of the images, and different power states of the scanner. Co nclusions. This roller-type scanner has a similar dynamic range to tha t of the film densitometer. The operating condition of the scanner is stable, and the resulting image is not significantly affected by the s canning positions. This type of scanner should be suitable for digitiz ing dental x-ray films, although the limiting scanning resolution migh t not be sufficient for some diagnostic purposes.