Performance of pixelated CsI scintillation screen with hexagonal array arrangement prepared by vacuum melting injection method

Abstract

The pixelated scintillation screen as an important component of the X-ray imaging detector effectively solves the issue of the lateral spreading of scintillation light and improves the spatial resolution of X-ray imaging. In this work, the hexagonal as well as square arranged pixelated CsI scintillation screens based on the silicon pore templates with pore pitch about 4μm and diameter about 3μm were fabricated by vacuum melting injection method. The morphology, crystallinity, X-ray excited optical luminescence and X-ray imaging performance of the screens were investigated. The results show that the CsI scintillator was filled into the silicon pore templates uniformly and compactly without microbubbles even if the depth of the filled CsI microcolumns reaches 100μm. The pixelated scintillation screen exhibits good CsI crystallinity with (110) preferred orientation. The intensity of X-ray excited optical luminescence of the hexagonal arranged pixelated CsI scintillation screen increases by 14.3% compared with that of the square arranged screen with same thickness. Furthermore, the intensity of the pixelated CsI screen with 100μm thickness is 34.1% higher than that of the screen with 40μm thickness. The spatial resolution of the X-ray imaging system with the hexagonal arranged pixelated CsI scintillation screen is about 115 lp/mm and not sensitive to the screen thickness, which is 11.5% higher than that with the square arranged screen. The detective quantum efficiency of the system with the hexagonal arranged pixelated CsI scintillation screen appears relatively higher than that with the square arranged screen with same thickness and increases with the thickness of the screen. This means the X-ray imaging performance of the hexagonal arranged pixelated CsI scintillation screen is better than that of the square array arranged screen.