[Investigation of low-contrast signal detection in computed radiography (CR)]

Threshold contrasts of low-contrast objects were compared between screen-film and computed radiography (CR) systems. Effects of incident exposure to the imaging plate (IP) and contrast enhancement on the detectability of low-contrast objects were also studied. We employed 18-alternative forced-choice (18AFC) experiments to study the dependence of the threshold contrasts of the test objects on the incident exposure, object size, and contrast enhancement. The results indicated that the threshold contrasts of CR system were comparable to that of the medium-speed screen-film system and increased by decreasing x-ray exposures. Although threshold contrasts decreased by contrast enhancement, the magnitude of improvement depended on the object size and incident exposure.