Thallium doped cesium iodide (CsI:Tl) scintillator films for the use as a converter for X-ray imaging detectors were fabricated by the thermal deposition method. The microstructures of these scintillating layers were affected by various deposition conditions such as vapor pressure, substrate temperature and post-heat treatment or rapid thermal annealing (RTA). CsI(Tl) scintillator films with various polycrystalline structures were manufactured under different process conditions and prepared for experiments. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the crystal structure and morphology properties. Light output and spatial resolution of the samples were strongly affected by the microstructures, which are determined by the deposition conditions and post-heat treatment. Imaging characteristics of the various CsI:Tl films were also measured under X-ray exposure conditions by coupling them to a CCD image sensor. (C) 2010 Elsevier B.V. All rights reserved.