1. A method of processing a Computed Tomography (CT) image, comprising: accessing an original CT image, wherein the original CT image is reconstructed from a first set of raw data and includes distortion representative of windmill artifacts; generating a high-frequency image by processing the original CT image with a first frequency division process; generating a low-frequency image by processing a plurality of thick images with a second frequency division process and combining the plurality of processed thick images, wherein the plurality of thick images is reconstructed from a second set of raw data that includes the first set of raw data, and each of the plurality of thick images includes substantially no distortion representative of windmill artifacts; generating an intermediate image by synthesizing the high-frequency image and the low-frequency image; and obtaining a target CT image based on the generated intermediate image.