1. A method for correcting a CT scan image, the method comprising: extracting a target image including a target region to be corrected from an original CT scan image; obtaining a target projection range corresponding to the target region by orthographically projecting the target image, and correcting target projection data within the target projection range to obtain corrected target projection data; generating noise-adjusted target projection data by adjusting noise of the corrected target projection data according to target projection data of an intensity domain which is obtained from target projection data of an attenuation domain, so as to improve noise consistency between the target region and rest of the CT original scan image; and reconstructing a corrected CT scan image based on the noise-adjusted target projection data; wherein adjusting noise of the corrected target projection data to generate the noise-adjusted target projection data comprises: converting the target projection data of the attenuation domain into the target projection data of the intensity domain; multiplying the target projection data of the intensity domain by a default transform coefficient so as to obtain a transformed target projection data; using the transformed target projection data as a Poisson parameter to calculate a Poisson random number, and determining update transformed target projection data based on the Poisson random number; transforming the update transformed target projection data to update target projection data of the intensity domain; converting the update target projection data of the intensity domain into update target projection data of the attenuation domain; and determining the update target projection data of the attenuation domain as the noise-adjusted target projection data.