Digital radiography with a large-area, amorphous-silicon, flat-panel X-raydetector system

RATIONALE AND OBJECTIVES. TO investigate the image quality of a digital rad iography system with an amorphous-silicon, large-area, digital flat-panel d etector. METHODS. A flat-panel detector based on a matrix of amorphous silicon was i ntegrated into a projection radiography system, The scintillator consisted of a layer of structured cesium iodide, The active matrix size of 3000(2) p ixels together with a pixel size of 143 mu m provided a large image area of 43 x 43 cm(2). Basic image quality parameters such as detective quantum ef ficiency (DQE) and modulation transfer function (MTF) were measured and com pared with those obtained with conventional systems, RESULTS. The measurement of DQE yielded a high value of 70% at zero spatial frequency. At a system dose equivalent to 400 speed, the DQE of the digita l system was a factor of two larger than the DQE of a storage phosphor or s creen-him system within the entire spatial frequency range between zero and the Nyquist limit of 3.5 Line pairs per millimeter, The flat-panel detecto r furthermore has an MTF that is superior to that in regular screen-film sy stems and also provides a substantially larger dynamic range. CONCLUSIONS. This new technology demonstrates its potential to provide equa l or superior image quality to conventional screen-him systems and to reduc e patient exposure to radiation dose. The advantages of digital radiography systems, based on a hat-panel detector as an instant image display, facili tation of work flow in the radiology department, and digital networking and archiving, are well in sight.