Routine Chest Radiography Using a Flat-Panel Detector

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Abstract
OBJECTIVE. The purpose of this study was to evaluate the effectiveness of a large-area, flat-panel X-ray detector for performing routine chest radiography at two different detector doses. MATERIALS AND METHODS. The chest radiographs of 50 patients (age range, 16-79 years; mean age, 57 years) were obtained at two different detector dose levels. Digital images were taken from the same patients in posteroanterior and lateral views with detector doses of 2.5 μGy and 1.8 μGy, respectively, at 125 kVp tube voltage. The cesium iodide—amorphous silicon active-matrix imager had a panel size of 43 × 43 cm, a matrix of 3000 × 3000, and a pixel pitch of 143 μm. Images were presented in a random order to three independent radiologists who were unaware of the dose level at which the images had been obtained. They subjectively rated image quality on a 4-point scale, according to six criteria (presentation of obscured lung, unobscured lung, airways, mediastinum and hilum, bony thorax, and overall impression). Statistical significance of differences was evaluated with Student's t test for paired samples (confidence level, 95%). RESULTS. Digital radiographs obtained at 2.5 and 1.8 μGy were equivalent on all quality criteria. No statistically significant differences and no tendency toward a preference for images obtained at one or the other dose level were observed. According to the registered mAs values, the average difference in patient dose was 33%. CONCLUSION. Use of flat-panel digital imagers based on the cesium iodide—amorphous silicon technique allows a considerable dose reduction during routine chest radiography without loss of image quality.