Lead oxide (PbO) for direct conversion fluoroscopic detectors
Master of Science
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Polycrystalline Lead Oxide (PbO) is being investigated as a photoconductive materials for application as X-ray-to-charge transducer in direct conversion x-ray detectors used in fluoroscopy and radiology. Previous usage of PbO films in Plumbicon vacuum tubes for optical imaging ensures its appropriate photoconductive properties. In combination with high X-ray absorption coefficient due to high atomic number of Pb and the theoretically established conversion gain together indicates high potential for radiological medical imaging application. Although very promising, at the current stage of development of PbO photoconductive layers thick enough for X-ray imaging applications have not yet achieved the expected conversion efficiency and not yet shown adequate temporal behavior for fluoroscopic applications: PbO suffers from image "lag” (i.e. the residual current following an x-ray pulse) and high dark current that limits the application of electric fields to below 3.5 V/μm, which is a major factor preventing the attainment of high conversion efficiency.