lead oxide (pbo) for direct conversion fluoroscopic detectors
abstract
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.