Fabrication and evaluation of a Gd₂O₂S:Tb phosphor screen film for development of a CMOS-based X-ray imaging detector

Abstract

In this study, Gd₂O₂S:Tb phosphor screen films were fabricated by using a special particle-inbinder sedimentation method. The phosphor particles used in this study were manufactured in two sizes, 2.5-μm and 5-μm. To evaluate luminescence efficiency and the spatial resolution according to the thickness, we fabricated screen films with thicknesses of 120, 150, 170, and 210-μm. The spatial resolution of the fabricated films was assessed by using an edge method to measure the modulation transfer function (MTF). From the experimental results, the spatial resolution of the mammography exposures (low-energy X-ray quality) was better than that of dental radiography (high-energy X-ray quality). Also, with the same film thickness, the screen with 2.5-μm particles had better resolution than the screen with 5.0-μm particles, but it showed about 20% lower resolution than a commercial Gd₂O₂S:Tb screen. In the evaluation of the results for the dependence of the spatial resolution on the film’s thickness, the 120-μm-thick screen showed the highest resolution, which was similar to that of a commercial screen.