Computed radiography utilizing laser-stimulated luminescence: detectability of simulated low-contrast radiographic objects.

Threshold contrasts of low-contrast objects with computed radiography (CR) images were compared with those of blue and green emitting screen-film systems by employing the 18-alternative forced choice (18-AFC) procedure. The dependence of the threshold contrast on the incident X-ray exposure and also the object size was studied. The results indicated that the threshold contrasts of CR system were comparable to those of blue and green screen-film systems and decreased with increasing object size, and increased with decreasing incident X-ray exposure. The increase in threshold contrasts was small when the relative incident exposure decreased from 1 to 1/4, and was large when incident exposure was decreased further.