A CT imaging method and apparatus in which an object is to be imaged by the CT apparatus using an X-ray or radiation, and a tomographic image of the object is obtained, wherein the object includes a reference portion. The processing the tomographic image is processed and a relative positional relation between a reference coordinate system of the object and a coordinate system of the CT apparatus is obtained. The object is imaged by the CT apparatus, and based on the relative positional relation, a tomographic image of a desired position of the object is obtained.