FLAT-PANEL X-RAY-DETECTOR USING AMORPHOUS-SILICON TECHNOLOGY - REDUCED RADIATION-DOSE FOR THE DETECTION OF FOREIGN-BODIES

RATIONALE AND OBJECTIVES. The authors evaluate a new flat-panel x-ray detector (FD) with respect to foreign body detection and reduction of radiation dose compared with screen-film radiography. METHODS. Flat-pa nel x-ray detector is based on amorphous silicon technology and uses a 1 k x 1 k photo-detector matrix with a poxel size of 143 x 143 mu m a nd 12-bit digital output. A thallium-doted cesiu iodide scintillation layer converts x-rays into light. A ex vivo experimental model was use d to determine the detectability of foreign bodies. Foreign bodies wit h varying sizes were examined: glass with and without addition of lead , bone, aluminium, iron, copper, gravel fragments, and graphite. Four hundred observation fields were examined using conventional radiograph y (speed, 400; system dose: 2.5 mu Gy) as well as FD with a simulated speed of 400, 800, 1200, and 1600, corresponding to a detector dose of 2.5 mu Gy, 1.25 mu Gy, 0.87 mu Gy, and 0.625 mu Gy, respectively. Fou r independent radiologists performed receiver operating characteristic analysis of 8000 observation. RESULTS. Flat-panel x-ray detector with a simulatio nspeed of 400 was significantly superior (P = 0.012) to s creen-film radiography (speed, 400). At a simulated speed of 800 and 1 200 FD yielded results equivalent to screen-film radiography. Flat-pan el x-ray detector was significantly inferior to screen-film radiograph y at a simulated speed of 1600 (P = 0.012). CONCLUSIONS. Flat-panel x- ray detector technology allows significant reduction in radiation dose compared with screen-film radiography without loss of diagnostic accu racy.