The present disclosure is directed to a system, method and apparatus for tracking an anatomical body part in a series of x-ray images. The anatomical body part moves due to a vital movement, such as breathing motion of the thorax. The anatomical body part is defined in a CT image acquired beforehand and is associated with a known movement phase during the vital movement. The series of x-ray images of the moving anatomical body part is taken. The movement phase associated with each one of the x-ray images is determined. In one implementation, the system may track the body part movement using external infrared-reflecting markers and a navigation system while taking a series of x-ray images and time-stamping the x-ray images and the positional information for the body part. The time stamps relate each one of the x-ray images with a specific movement phase of the body part. The specific x-ray image being associated with the same movement phase as the CT image is determined and the representation of the anatomical body part defined in the CT image can be determined in the x-ray image by comparing the CT image with the specific x-ray image. The specific x-ray image may be compared to the other x-ray images to find the anatomical body part in those x-ray images and preferably highlight it to be easily recognized by a user.
