Evaluation of an enhanced digital film-duplication system by receiver operating characteristic analysis

RATIONALE AND OBJECTIVES. Over- or underexposure often results in poor quality radiographs. Using receiver operating characteristic analysis, the authors investigated the potential utility of a system that corrects densities in such images to improve the accuracy of lung nodule detection. METHODS. Chest radiographs were digitized by a laser film digitizer. Simulated nodules were superimposed on 36 improperly exposed chest radiographs. All images, with and without nodules, were then processed by a nonlinear density-correction technique. Hard-copy images were produced by a laser film printer. Eight radiologists evaluated the corrected and uncorrected images for the presence or absence of lung nodules using a continuous (0-100) confidence-rating scale. RESULTS. The detectability of lung nodules improved significantly in the retrocardiac/retrodiaphragmatic regions of underexposed images and in the peripheral lung region of overexposed images. CONCLUSIONS. This system may increase diagnostic accuracy in detection of lung nodules in improperly exposed images.