A method for correcting a CT scan image is provided. A target image including a target region to be corrected is extracted from an original CT scan image. A target projection range corresponding to the target region is obtained by orthographically projecting the target image, and target projection data within the target projection range is corrected. Noise of the corrected target projection data is adjusted to generate noise-adjusted target projection data to improve noise consistency between target region and the rest of the CT scan image. A corrected CT scan image is reconstructed based on the noise-adjusted target projection data.