“…In order to improve the modulation transfer function characteristics of the phosphor-based indirect detectors, structured scintillators, such as the columnar growth CsI, are generally used. 26,28,29 Hence, the optical scattering at the top surface of the columnar CsI growth, 30,31 the grain boundaries, and the disorder structure 32 can cause spatial sensitivity variations. Therefore, the acquired images are affected by the fixed pattern noise due to the nonuniform gains.…”