A TiO2-Coated Reflective Layer Enhances the Sensitivity of a CsI:Tl Scintillator for X-ray Imaging Sensors

Columnar-structured cesium iodide (CsI) scintillators doped with thallium (Tl) are frequently used as x-ray converters in medical and industrial imaging. In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers―aluminum (Al), chromium (Cr), and titanium dioxide (TiO2) powder―coated on glass substrates. We used two effusion-cell sources in a thermal evaporator system to fabricate CsI:Tl films on substrates. The scintillators were observed via scanning electron microscopy (SEM), and scintillation characteristics were evaluated on the basis of the emission spectrum, light output, light response to x-ray dose, modulation transfer function (MTF), and x-ray images. Compared to control films without a reflective layer, CsI:Tl films with reflective layers showed better sensitivity and light collection efficiency, and the film with a TiO2 reflective layer showed the best properties. KCI Citation Count: 2