1. An X-ray imaging apparatus comprising: a plurality of X-ray generation modules configured to emit X-rays to a subject, the X-ray generation modules being configured to move independently of one another; an X-ray detector configured to detect a plurality of X-rays emitted from the plurality of X-ray generation modules and which have passed through the subject; and an image processor configured to acquire a plurality of X-ray images from the plurality of detected X-rays.