Effect of size and position on chest lesion detection.

A test series of radiographs was developed by duplicating normal chest radiographs with superimposed masks containing either a 0.5, 1.0, or 1.5 cm pseudolesion. Nine observers participated in the study. Receiver operating characteristic curves were formed and the responses from radiologists and physicists compared. The accuracy rate for detecting 1.0 and 1.5 cm lesions was 44%; for 0.5 cm lesions, 8%. Lesions located in the upper left quadrant were detected with an accuracy of 56% compared to 29% for those in the lower left quadrant.