CLINICAL-APPLICATION OF A FLAT-PANEL X-RAY-DETECTOR BASED ON AMORPHOUS-SILICON TECHNOLOGY - IMAGE QUALITY AND POTENTIAL FOR RADIATION-DOSE REDUCTION IN SKELETAL RADIOGRAPHY

OBJECTIVE. The purpose of this study was to compare images obtained wi th a self-scanning, flat-panel X-ray detector based on amorphous silic on technology with conventional screen-film radiographs and to evaluat e the possibility of radiation dose reduction in skeletal radiography. SUBJECTS AND METHODS. One hundred twenty patients were examined prosp ectively using a conventional screen-film system (speed, 400; detector dose, 2.5 mu Gy) and a prototype digital amorphous silicon detector ( simulated speed, 400 and 800, n = 120; simulated speed, 1600, n = 40). The resulting 400 images were evaluated independently by six radiolog ists using a subjective five-point preference scale that rated overexp osure, underexposure, contrast resolution, spatial resolution, and sof t-tissue presentation. Image quality was ranked on a scale from 0 to 1 0 according to subjective criteria. Statistical significance of differ ences was determined using Student's t test and confidence intervals ( 95% confidence level). RESULTS. Comparison of conventional radiographs with digital images revealed a statistically significant preference f or the digital system for soft-tissue presentation (speed 400 and 800) and visualization of osteoarthrotic changes (speed 400). A small but statistically significant preference for conventional images was found with respect to contrast and spatial resolution when digital speed wa s 800 or 1600; and the visibility of arthrosis at digital speed 1600, osteolysis at digital speed 800 and 1600, and fractures at digital spe ed 1600. CONCLUSION. The amorphous silicon-based system with a simulat ed speed of 400 provided images equivalent to screen-film radiographs. For clinical tasks such as routine follow-up studies, assessment of i nstability, or orthopedic measurements, a radiation dose reduction of up to 75% may be possible.