Recently about 90% of radiographs have been taken by the digital radiographic system in Japan, but the exposure dose of the patients are about ten-times different among the systems. We understood it by a surveytaken in 2007. We studied the visual evaluation with varying exposure doses using the image phantom of the lumber AP, lumber lateral and hip AP. Additionally we measured quantum efficiency (DQE) of the digital systems. We also studied the exposure index (EI) of IEC standard to see whether it is able to be the sensitivity index among the digital systems. DQE in 1.0 cycle/mm of CR, FPD (GOS), FPD (CsI, a-Se) became 0.2–0.25, 0.3, 0.5, respectively. Our results display that the dose reduction is relative to DQE. The visual evaluation results also show that dose reduction is possible among the systems. From these results, we are able to reduce the exposure dose of the patients at the clinical site. We also suggest that we manage the exposure dose using the E.I of the IEC standard.
