1. An X-ray Computed Tomography (CT) imaging apparatus, comprising: an imaging device for radiating an X-ray onto an object and detecting the X-ray having been transmitted through the object; a magnification ratio determination unit for determining a magnification ratio for images of the object using at least one of hardware attributes of the imaging device and a size of an input voxel; and a magnification ratio controller for moving the imaging device in accordance with the determined magnification ratio, wherein the hardware attributes comprise at least one of a focal spot size, a pixel size, and resolution of the imaging device; and wherein the magnification ratio determination unit includes: a first magnification ratio determination unit for determining a first magnification ratio based on the hardware attributes of the imaging device; a second magnification ratio determination unit for determining a second magnification ratio based on the size of the input voxel; and a third magnification ratio determination unit for determining a third magnification ratio for the images of the object, based on the first magnification ratio and the second magnification ratio, wherein the determined third magnification ratio for the images of the object is greater than a less value of the first and second magnification ratios and is less than a greater value of the first and second magnification ratios.