1. An examination method for examining an examination target region of an examination object by capturing images from X-rays output from an X-ray source and transmitted through the target region with an X-ray detection unit, reconstructing a three-dimensional image of the examination target region based on the captured images, and examining the examination target region using the three-dimensional image obtained by the reconstruction, the method comprising the steps of: changing a position of the X-ray detection unit on a virtual circle having an optical axis of the X-ray source as a center on a virtual plane, that intersects perpendicularly with the optical axis; causing the X-ray detection unit to perform X-ray fluorography at each of a plurality of positions on the virtual circle; generating an X-ray computed tomography (CT) image based on the result of the X-ray fluorography by the X-ray detection unit; and generating a tomosynthetic tomographic image based on the same result of the X-ray fluorography as used for the generation of the X-ray computed tomography (CT) image; wherein the step of changing the position of the X-ray detection unit includes changing the position of the X-ray detection unit so that a direction of a coordinate system of the image captured by the X-ray detection unit at each of a plurality of positions on the virtual circle remains unchanged.