Chest radiography with a large-area detector based on cesium-iodide/amorphous-silicon technology - Image quality and dose requirement in comparison with an asymmetric screen-film system

The purpose of this study was to evaluate a large-area, flat-panel X-ray de tector, which uses cesium-iodide (CsI) and amorphous silicon (a-Si). Conven tional images were compared with digital images acquired with equal dose (2 .5 mu Gy) and with 50% dose reduction. Fifteen consecutive patients were st udied prospectively using an asymmetric screen-film system (detector dose, 2.5 mu Gy). Digital images were taken from the same patients in a posteroan terior view with detector doses of 2.5 and 1.25 mu Gy, respectively. The Cs I/a-Si active-matrix imager had a panel-size of 43 x 43 cm, a matrix of 3 x 3k, and a pixel-pitch of 143 mu m. Hard copies were presented in a random order to eight independent observers, who rated image quality according to six subjective quality criteria. Statistical significance of differences wa s evaluated with Student's t test for paired samples (confidence level, 95% ). Digital radiographs with 2.5 and 1.25 mu Gy were superior to conventiona l images regarding all quality criteria. Statistically significant differen ces were observed for five of six criteria at a detector dose of 2.5 mu Gy and for only one quality feature at 1.25 mu Gy. mat-panel digital imagers b ased on CsI/a-Si technique have the potential to replace conventional syste ms and might allow a reduction of radiation dose by 50% without loss of ima ge quality.