1. An X-ray imaging apparatus comprising: an X-ray generator configured to direct X-rays to a subject; an X-ray detector that detects X-rays generated by the X-ray generator and outputs image data; an image processor that receives the image data output by the X-ray detector and produces a plurality of 2-dimensional (2D) images of the subject, wherein the image processor is configured to: generate a 3-Dimensional (3D) image of the subject from the plurality of 2D images of the subject, generate a 3D blood vessel image by extracting blood vessel information from the 3D image of the subject, generate a 2D blood vessel image by projecting the 3D blood vessel image onto a 2D plane, overlap the 2D blood vessel image with a 2D fluoroscopy image to acquire a 2D roadmap image corresponding to a first position, detect a location of a surgical tool from the 2D roadmap image corresponding to the first position, detect a blood vessel corresponding to the location of the surgical tool from the 3D blood vessel image, mark the location of the surgical tool with an identifier in the detected blood vessel; and a display configured to display the 2D roadmap image, the detected blood vessel, and the identifier.