Digital radiography of the skeleton using a large-area detector based on amorphous silicon technology: Image quality and potential for dose reductionin comparison with screen-film radiography

AIM: The purpose of this study was to evaluate a large-area, flat-panel X-r ay detector (FD), based on caesium-iodide (CsI) and amorphous silicon (a-Si ) with respect to skeletal radiography, Conventional images were compared w ith digital radiographs using identical and reduced radiation doses. MATERIALS AND METHODS: Thirty consecutive patients were studied prospective ly using conventional screen-film radiography (SFR; detector dose 2.51 mu G y). Digital images were taken from the same patients with detector doses of 2,5, 1.25 and 0.625 mu Gy, respectively. The active-matrix detector had a panel size of 43 x 43 cm, a matrix of 3 x 3K, and a pixel size of 143 mu m, All hard copies were presented in a random order to eight independent obse rvers, who rated image quality according to subjective quality criteria. Re sults were assessed for significance using the Student's t-test (confidence level 95%). RESULTS: A statistically significant preference for digital over convention al images was revealed for all quality criteria, except for over-exposure ( detector dose 2.5 mu Gy) Digital images with a 50% dose showed a small, sta tistically not significant, inferiority compared with SFR, The FD-technique was significantly inferior to SFR at 75% dose reduction regarding bone cor tex and trabecula, contrast and overall impression. No statistically signif icant differences were found with regard to over- and under-exposure and so ft tissue presentation, CONCLUSION: Amorphous silicon-based digital radiography yields good image q uality, The potential for dose reduction depends on the clinical query. (C) 2000 The Royal College of Radiologists.