Digital radiography with photostimulable storage phosphors. Control of detector latitude in chest imaging.

RATIONALE AND OBJECTIVES. A widely used digital radiography system based on a photostimulable storage phosphor (PSP) detector was analyzed with regard to radiographic contrast changes that result from the adjustment of detector latitude (x-ray sensitivity range) in the normal processing of chest images. METHODS. Images of an acrylic step wedge were acquired using the digital system in a mode that permitted direct control of effective detector latitude. The images were post-processed in conditions duplicating those used for portable chest examinations, and contrast was measured. RESULTS. Increases in effective detector latitude provided only marginal radiographic contrast gains in the subdiaphragm-equivalent areas of the laser-printed digital film image, while causing large reductions in radiographic contrast in the lung-equivalent region. CONCLUSION. Detector latitude is an important variable that should be monitored or controlled in investigations that compare reader performance using conventional and digital systems.