Effects of luminance and resolution on observer performance with chest radiographs

PURPOSE: To examine the combined effects of image resolution and display lu minance on observer performance for detection of abnormalities depicted on posteroanterior chest radiographs. MATERIALS AND METHODS: A total of 529 radiographs were displayed on a speci ally constructed view box at three luminance levels (770, 260, and 85 cd/m( 2)) and three resolutions (100-mu m, 200-mu m, and 400-mu m pixels). Each i mage was reviewed nine times by six radiologists who participated in this s tudy. The abnormalities included nodule, pneumothorax, interstitial disease , alveolar infiltrates, and rib fracture. Negative (normal) radiographs wer e also included. REULTS: Receiver operating characteristic curves indicated that the effect of image luminance was greater than that of resolution. The detection of pn eumothorax, interstitial disease, and rib fracture showed statistically sig nificant differences (P < .05) due to luminance. The detection of pneumotho rax was the only abnormality with a statistically significant difference du e to resolution. There was no evidence that luminance was related to image resolution for any of the abnormalities. CONCLUSION: At a resolution of 400-mu m pixels or higher across the field o f view and a luminance of 260 cd/m(2) or more, primary diagnosis with poste roanterior chest radiographs is not likely to be affected by the quality of display.