1. A combined positron emission tomography (PET) and X-Ray computerized tomography (CT) tomograph for acquiring PET and CT images with a known geometric relationship between pixels of said images, said combined PET and X-Ray CT tomograph comprising: a CT scanner having a patient gantry, said CT scanner including a plurality of detectors, said CT scanner being provided for acquiring a CT image; a PET scanner having a patient gantry separate from said CT scanner patient gantry, said PET scanner including a plurality of detectors, said PET scanner being provided for acquiring a PET image; a patient support for supporting a patient positioned within each of said CT scanner patient gantry and said PET scanner patient gantry, said patient support being movable axially within each of said CT scanner patient gantry and said PET scanner patient gantry; and a display device for displaying at least one of said CT image, said PET image and a fused PET/CT image generated by said combined PET and X-Ray CT tomograph.