In vitro perception of low-contrast features in digital, film, and digitized dental radiographs: A receiver operating characteristic analysis

Objective. To compare experimentally the image quality of charged-coupled device ( CCD)-based digital, flatbed scanner digitized, and dental film radiographs. Study design. High-contrast standardized radiographs of an aluminum step wedge containing boreholes were obtained on dental radiographic film (F) and a CCD receptor (D). Digitization (S) was done with a flatbed scanner. Each radiograph was separated into 23 single images, 18 of which showed a dark spot. Thirty observers indicated their confidence on the visibility of the spots for a receiver operating characteristic (ROC) analysis. Results. Mean Az values (area beneath the ROC curves) differed significantly (P < .05), being highest for D (Az = 0.76), followed by F (Az = 0.71) and S (Az = 0.60). Mean sensitivity of S (0.45) was significantly (P = .000) lower than for D (0.66) and F (0.67). Conclusion. The difference between modality D and F was small. However, the inferior performance of S images, particularly in dark regions, could be clinically relevant.