Electrical Characteristics of Intraoral Dental Imaging Devices Based on the CMOS Imager Coupled with Integrated X-ray Conversion Fiber Optics

As a continuation of our digital X-ray imaging sensor R&D, we have developed a cost-effective, intraoral imaging device based on the CMOS photosensor array coupled with an integrated X-ray conversion fiber-optic faceplate. It consists of a commercially available CMOS photosensor of a 35 times 35 mum² pixel size and a 688 times 910 pixel array dimension, and a high efficiency columnar CsI(Tl) scintillator of a 90 mum thickness directly deposited on a fiber-optic faceplate of a 6 mum core size and an 1.46 mm thickness with 85/15 core-cladding ratio (NA~1.0 in air). The fiber-optic faceplate is a highly X-ray attenuating material that minimizes X-ray absorption on the end CMOS photosensor array, thus, minimizing X-ray induced noise at the photosensor array. It uses a high light-output columnar CsI(Tl) scintillator with a peak spectral emission at 545 nm, giving better spatial resolution, but attenuates some of this light due to interfacial and optical attenuation factors. In this paper, we presented the performance analysis of the intraoral imaging device with experimental measurements and acquired X-ray images in terms of modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE).