Laminate structure detectors for low dark current with photoconductors indigital X-ray imaging

摘要

The Particle-In-Binder method is one of the excellent processes for a direct conversion X-ray detector.Although detectors coated by the particle-in-binder method provide high sensitivity in X-ray exposure,the dark current is quite high in medical devices. To decrease the dark current and improve theefficiency of detectors, we investigated the potential for a flat-panel X-ray detector with a laminatestructure including a plurality of metal halide films. The dark current decreased by laminating thehexagonal lattice, matching the metal halide photoconductive layers and adjusting the Fermi level so ithad a different band gap. Film samples of PbO on PbI_2and BiI_3on HgI_2, 3 cm x in area, weredeposited by the particle-in-binder process onto glass substrates with conductive coatings, and indium-tin oxide (ITO) was deposited onto laminate layers as a top electrode by using the sputtering process.They were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) to observestructural and morphological properties. To also investigate electrical characteristics, dark current, andsensitivity to X-ray exposure in the energy range of chest radiography, diagnosis and signal lag weremeasured at the range of operating voltage. As a result, although the sensitivity of the film decreased,the efficiency of the film improved due to a decrease in dark current. It is proposed that a laminatestructure of photoconductors to reduce dark current in flat-panel detector for image quality in digitalradiography can be used.