Factors determining the diagnostic accuracy of digitized conventional intraoral radiographs

A number of factors may determine the diagnostic accuracy of digitized intraoral radiographs. Conventional film radiographs were digitized with three different digitizers, a laser-scanner, a drum-scanner and a TV camera. Digital images, varying in pixel size, grey level and image processing, were displayed on three different video-monitors and assessed by 10 dentists. The detectability of incipient proximal surface caries was used as an index of the diagnostic accuracy and the effect of the different factors compared by means of receiver operating characteristic (ROC) analysis. Images digitized by the drum-scanner were found to have the best diagnostic accuracy. Sufficient diagnostic accuracy could be attained on the low-cost video monitor of a personal computer. Digital images with a pixel size of 100 microns and 32 grey levels were found to be acceptable for intraoral radiographs for diagnostic purposes. These results provide a practical guide for establishing a digital image acquiring system for any intraoral radiographs, reducing demands on data storage to a minimum.