This study compared the diagnostic quality of E-speed film, xeroradiographic cassettes, and a screen-film imaging system used in medical radiology. The surfaces of defects simulating caries were scored for the presence and depth of the defects under ideal viewing conditions by independent observers. Receiver Operator Characteristics analysis of the data showed no significant differences regarding diagnostic potential among the three systems. The true-positive fraction was 1.00 for all systems and all operators, and the false-positive fraction was .011, .011, and .007, respectively. An exposure of 5.5 mR was used to produce images with the screen-film combination, and 150 mR was used for standard dental systems. This study showed that an exposure reduction of 96% is possible while maintaining high-quality radiographs for the diagnosis of caries.