LAUSR

The effect of pixel size of CsI(Tl) scintillation screen based on oxidized silicon micropore array template on spatial resolution and light output in X-ray imaging was investigated by using Geant4 Monte Carlo simulation code. The quantitative relations between the pixel size and the spatial resolution as well as the light output were obtained. The results reveal that the pixelated structure can largely improve the spatial resolution of the screen. It improves rapidly when the pixel size decreases from 60 μm to 10 μm. Unlike that of a conventional scintillation screen, the spatial resolution of the pixelated CsI(Tl) scintillation screen isn't obviously deteriorated by increasing the thickness of the screen. As far as the relation between the spatial resolution and X-ray energy is concerned, the resolution does not change significantly with X-ray energy when the energy is less than 80 keV . When the X-ray energy exceeds 80 keV, the spatial resolution becomes sensitive to X-ray energy because the effect of Compton scattering cannot be neglected. The light output increases with the increase of the pixel size, but doesn't change significantly with the thickness of the screen when the thickness is three times more than the X-ray attenuation length. In addition, the angular distribution of the emitted scintillation light from the screen was studied. The maximum emission occurs at the angle about 46° relative to the normal direction of the screen.