Digital Radiography of the Skeleton Using a Large-Area Detector Based on Amorphous Silicon Technology: Image Quality and Potential for Dose Reduction in Comparison with Screen-Film Radiography

AIM: The purpose of this study was to evaluate a large-area, flat-panel X-ray detector (FD), based on caesium-iodide (CsI) and amorphous silicon (a-Si) with respect to skeletal radiography. Conventional images were compared with digital radiographs using identical and reduced radiation doses. MATERIALS AND METHODS: Thirty consecutive patients were studied prospectively using conventional screen-film radiography (SFR; detector dose 2.5μGy). Digital images were taken from the same patients with detector doses of 2.5, 1.25 and 0.625μGy, respectively. The active-matrix detector had a panel size of 43×43cm, a matrix of 3×3K, and a pixel size of 143μm. All hard copies were presented in a random order to eight independent observers, who rated image quality according to subjective quality criteria. Results were assessed for significance using the Student's t -test (confidence level 95%). RESULTS: A statistically significant preference for digital over conventional images was revealed for all quality criteria, except for over-exposure (detector dose 2.5μGy). Digital images with a 50% dose showed a small, statistically not significant, inferiority compared with SFR. The FD-technique was significantly inferior to SFR at 75% dose reduction regarding bone cortex and trabecula, contrast and overall impression. No statistically significant differences were found with regard to over- and under-exposure and soft tissue presentation. CONCLUSION: Amorphous silicon-based digital radiography yields good image quality. The potential for dose reduction depends on the clinical query.Volk, M. (2000). Clinical Radiology55, 615–621.