A prototype digital chest system, which uses storage phosphor technology and has the advantages over existing computed radiography systems (CR) of compactness and immediate image display, is being evaluated in our laboratory. We evaluated the imaging properties of the Konica Direct Digitizer (KDD) in order to assess its potential usefulness for general clinical use, or as a front-end for a PACS. The prototype system consists of a new stimulable phosphor (RbBr:Tl) detector read by a compact semiconductor laser scanning system, with images immediately displayed on a CRT or transferred to a host computer. The imaging characteristics of resolution and noise were evaluated, using display parameters matched to a Kodak Lanex Medium/OC system. Preliminary results using sensitive composite test objects show an increase in noise and a slight decrease in resolution as compared to conventional radiography. However, subjective comparison of a chest phantom and volunteer images indicates that these differences may not be clinically significant. Further development is needed to provide increased absorption, and thus improved image quality.