DETECTION OF SIMULATED CHEST LESIONS WITH NORMAL AND REDUCED RADIATION-DOSE - COMPARISON OF CONVENTIONAL SCREEN-FILM RADIOGRAPHY AND A FLAT-PANEL X-RAY-DETECTOR BASED ON AMORPHOUS-SILICON

RATIONALE AND OBJECTIVES. The authors compared a solid-state amorphous silicon (a-Si) detector and screen-film radiography (SFR) with regard to the detection of simulated pulmonary lesions. Evaluation of the im pact of a dose reduction of 50% with this digital flat-panel detector was of special interest. METHODS. A self-scanning flat-panel detector, based on a-Si technology with 143 x 143 mu m pixel size, 1 k x 1 k ma trix and 12-bit digital output was used. An asymmetric state-of-the-ar t screen-film system was compared with a-Si images taken at the same d ose as SFR-images and at a dose reduced by 50%. An anthropomorphic che st phantom was superimposed by templates containing nodules, linear st ructures, reticular, and micronodular opacities in a random distributi on. Receiver operating characteristic analysis was performed for 23,04 0 observations made by four independent observers. Student's t test (9 5% confidence-level) was used for statistical analysis. RESULTS. Recei ver operating characteristic analysis showed that a-Si images taken at the same dose as SFR-images were significantly superior to SFR with r espect to the detectability of lines (P = 0.01) and micronodular opaci ties (P < 0.01). For the other objects and the a-Si images taken at a reduced dose, it yielded no statistically significant differences betw een both imaging modalities. CONCLUSIONS. The results of this phantom study indicate that a-Si detector technology holds promise in terms of dose reduction in chest radiography without loss of diagnostic accura cy compared with SFR.