Subjective image quality of solid-state and photostimulable phosphor systems for digital intra-oral radiography

Objectives: To compare subjectively the image quality of intra-oral radiographs from six digital systems. Methods: Two generations of two different solid-state detectors; Visualix-1 and -2 (Gendex Dental Systems, Milan, Italy), Computed Dental Radiography (CDR) and CDR Active Pixel Sensor (APS) (Schick Technologies Inc., Long Island City, NY, USA), and two photostimulable phosphor (PSP) systems; Digora (Soredex, Orion Corporation, Helsinki. Finland) and DenOptix (Gendex Dental Systems, Milan, Italy) were compared. Tooth-containing specimens from different areas of dried mandibles were radiographed at exposures between 91 - 9400 mu Gy. Images were transferred to a personal computer, displayed in random order and evaluated in their original form and after applying a histogram equalisation algorithm. Eight observers graded subjective image quality using a 5-point scale. Results: Both CDR systems scored highest for image duality but within the narrowest exposure range. The Visualix images received the lowest scores. The PSP systems produced acceptable image quality at both lower and higher exposures than the solid-state systems. Enhanced images were generally considered to be inferior to the original images, except for those produced by the four solid-state systems at very low exposures. Conclusions: (i) the PSP systems provided a clinically acceptable image duality over a wide exposure range; (ii) the CDR systems had the best image duality but over the narrowest exposure ranges; (iii) the Visualix systems had the lowest image quality; and (iv) histogram equalisation did not generally improve image quality.