Exposure parameters and their effects on diagnostic accuracy.

A new method for analyzing diagnostic accuracy is introduced. A diagnostic accuracy curve may be obtained by plotting receiver operating characteristic analysis data, P(A), as a function of exposure. By means of diagnostic accuracy curves the effects on diagnostic accuracy of tube potential, exposure, and size of carious lesions was studied. It was found that the effect of the tube potential on the accuracy of caries diagnosis is negligible. About 25% of the variation in diagnostic accuracy depends on the exposure and about 80% on lesion depth. With the lesion depth constant, about 75% of the variance in diagnostic accuracy depended on observer performance. The peak of a diagnostic accuracy curve indicates optimum performance. This is found at an exposure that gives a radiographic density of about 1 in enamel and dentin although the tolerable exposure increases with increased lesion depth.