DIRECT CONVERSION DETECTOR FOR DIGITAL FLUOROSCOPY

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Fluoroscopy is a very important modality for dynamic radiographic imaging and provides vital information about internal structure, flow and movement in a patient. Fluoroscopy is widely used in procedures such as subtraction angiography, gastro-intestinal imaging, cardiovascular imaging as well as in other interventional radiological studies. Currently fluoroscopic studies are performed using image intensifiers (XRII) which have large field of view and fast framing capabilities. However, the XRII have significant drawbacks in terms of size, flexibility and cost. They also suffer from veiling glare and show image- distortions at edges. Finally, they have limited dynamic range and moderate DQE. To address this situation, we propose to develop a large area flat panel, digital imaging detector by combining high resistivity semiconductor film (of lead iodide, Pbl2) technology being developed at RMD with the large format amorphous silicon (a-Si:H) readout technology which has been developed by our collaborator, Dr. Robert Street at Xerox PARC. In this approach, pixellated Pbl2 film acts as the sensor producing electron-hole pairs directly upon X-ray interaction, and a-Si:H readout circuitry provides low noise, real time readout of each Pbl2 pixel. The overall system provides wider dynamic range and higher detection efficiency (than XRII) and therefore offers possibility of equivalent images at lower dose. Finally, Pbl2 films and a-Si:H readout can be prepared in large areas at low cost, and hence cost effective large area detectors (20 cm x 20 cm) can be developed. The Phase l project will focus on demonstrating the feasibility of this promising detector concept. PROPOSED COMMERCIAL APPLICATIONS: Besides the large medical radiographic imaging market, the proposed detector would find wide acceptance in other applications such as non destructive testing, X-ray diffraction, and high energy physics.