Image quality of digital chest radiography: evaluation of subtle interstitial lung abnormalities (preliminary study)

To evaluate the image quality of storage phosphor radiography (SR) for diagnosing subtle interstitial lung abnormalities, we studied the differences between conventional screen-film radiography (FR) and SR in 38 patients. Nineteen patients had subtle interstitial lung abnormalities and the others had normal chests. Two formats of hard copies were used for SR; a full-size SR (14 x 14 inches, 0.2-mm pixel size) and a minified SR (9 x 9 inches, 0.13-mm pixel size). Readings were carried out by 14 readers (7 chest radiologists and 7 residents). The area under the receiver operating characteristic curve was used to evaluate the results. For the 14 readers no significant differences in observer performance were observed among the three image sets (FR, full-size SR, minified SR), while for the seven chest radiologists significant differences were observed between FR and the two formats of SR. The best perceptual accuracy was obtained with FR as evaluated by the seven chest radiologists. In conclusion, while overall performance with digital and conventional radiographs was almost the same as far as diagnosing subtle interstitial lung abnormalities, significant differences between FR and SR were found by chest radiologists. Critically important information may be lost in commercially available SR.