Fabrication and imaging characterization of high sensitive CsI(Tl) and Gd_2O_2S(Tb) scintillator screens for X-ray imaging detectors

摘要

Indirect-detection methods consisted of an X-ray converter and photodiode arrays are more widely used in medical diagnosis and industrial fields. Two major scintillation materials such as terbium-doped gadolinium oxysulfide(Gd_2O_2S:Tb, Gadox) and thallium-doped cesium iodide(CsI:Tl) are commonly used. In this work, Gadox screens were manufactured by particle in binder (PIB) layer method and CsI:Tl scintillator films with columnar structure were also fabricated by thermal evaporation method onto glass substrates. Furthermore, two sample screens were coated to increase the light collection efficiency by white TiO_2 reflective layers. The scintillation properties, such as emission spectrum and light output of these materials were measured by X-ray luminescence condition. In order to investigate the imaging performance of both Gadox and CsI:Tl scintillation screens as converters of X-ray imaging detectors, these materials were optically coupled with a 2D CCD image sensor. The light response to X-ray dose, spatial resolution and X-ray images were measured and analyzed under X-ray imaging system condition.