An objective comparison of four digital intra-oral radiographic systems: sensitometric properties and resolution

Objectives: To compare the sensitometric properties and resolution of four digital intra-oral radiographic systems. Methods: Three CCD-based systems were evaluated, RVG-4 (Trophy Radiologic, Paris, France) CDR (Schick Technologies Inc, Long Island, NY, USA) and Dixel (Morita, Kyoto, Japan) and a photostimulable phosphor system (Digora, Soredex-Orion, Helsinki, Finland). The sensitometric properties were determined by measuring the gray levels at increasing exposures without making ally gray-scale adjustments. MTF was measured using images of a 10 mu m width slit inclined to the long and short axes of the detectors. Results: The CCD-based systems showed a linear relationship between exposure and gray level although there were some differences in sensitivity. In RVG-4, the gray level saturated at a lower exposure. Digora showed a logarithmic relationship at uniform exposure. However, there was a linear relationship when it was exposed below the calibration dose. The MTF was highest with RVG-4 and the lowest with the Digora. Conclusions: Each system has its own specific properties; RVG-4 has the highest resolution with the narrowest latitude: whereas Digora has the wider latitude but the lowest resolution.