Light collection enhancement of the digital x-ray detector using Gd2O2S:Tb and CsI:Tl phosphors in the aspect of nano-scale light dispersions

The nano-scopic light collection is investigated for the Active Matrix Flat-Panel Imagers (AMFPIs). The simulations using two kinds of screens are shown for light collection of x-rays. Enhancement of the light collection is accomplished by the microlens system incorporated with x-ray detector. For digital radiographic and mammographic applications, indirect detection imagers use Gd2O2S:Tb or CsI:Tl scintillation screens to convert the x-ray into visible photons. The light collection efficiencies for Gd2O2S and CsI are obtained. In Gd2O2S, the 27 kVp and 82 μm are the highest light collection cases in both Lambertian and Isotropic geometries. In CsI, 20 keV and 150 μm case have the highest light collection efficiency. So, x-ray energy and scintillator thicknesses are considered as the optimized light collection. The optimum thickness and x-ray energy combination are used for the detector of this study. In this paper, it is concluded that the screens between 17 kVp and 25 kVp have higher light collections, which could be considered as the clinical purposes if it is necessary. This energy range is compared with other energy cases, which are examined in the study. - Highlights: → The light collection efficiency could be increased by the microlens optically focusing method. → The lens focuses on the lights of the nano-scale photon distributions. → This depends on the angular distribution of the photons. → The quantum quantity is obtained by the x-ray energy and screen thickness. → The image blur can be decreased by the photon detection numbers in the photodetector.