HIGH-RESOLUTION X-RAY IMAGING BASED ON PIXEL-STRUCTURED CSI:TL SCINTILLATING SCREENS FOR INDIRECT X-RAY IMAGE SENSORS

摘要

We introduce the development of pixel-structured screens with thallium-doped CsI(CsI:Tl) scintillator for indirect digital X-ray imaging sensors. The indirect-conversion detection method based on the pixel-structured CsI:T1 scintillator provides high spatial resolution X-ray imaging without sacrificing the light spreading in thick scintillation layers. The scintillation screens was fabricated by using a vacuum deposition process and filling the CsI:T1 scintillating powders into two-dimensional pixel-structured silicon array. The pixel-structures with 100μm and 50μm pixel size with a wall width of 20μm and 200μm thick depth were prepared and the fabricated CsI:T1 scintillating powders were filled into trench of pixel structure through a vacuum process. The final scintillation screens with 2.5cm × 2.5cm size were prepared and directly coupled to CCD image sensor with optical lens for performance evaluation of X-ray imaging characterization. The imaging performance of the samples was investigated in terms of relative light intensity, X-ray linearity and spatial resolution under practical X-ray exposure condition. These preliminary results imply that pixel-structured CsI:Tl scintillating screens shows high spatial resolution by less lateral spreading of emitted visible photons within pixel-structured silicon arrays. However, these X-ray detectors is still requiring the improved X-ray sensitivity by coating the reflective layer onto inner silicon wall surface and filling the scintillating power into pixel-structures by completely.