A method and apparatus for medical image synthesis is disclosed, which synthesizes a target medical image based on a source medical image. The method can be used for synthesizing a high dose computed tomography (CT) image or a high kV CT image from a low dose CT image or a low kV image. A plurality of image patches are extracted from a source medical image. A synthesized target medical image is generated from the source medical image by calculating voxel values in the synthesized target medical image based on the image patches extracted from the source medical image using a machine learning based probabilistic model.
