1. An examination method for examining an examination target region of an examination object by capturing images from X-rays output of an X-ray source with an X-ray detection unit, the X-rays output being transmitted through the target region of the examination object, 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 along a circumference of a virtual circle, the X-ray source having an optical axis intersecting the center of the virtual circle, the optical axis being perpendicular to the surface of the virtual circle, the examination object being located away from the optical axis and between the X-ray source and the X-ray detection unit; activating the X-ray detection unit to perform X-ray fluorography at each of a plurality of positions along the circumference of 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 during the step of generating the X-ray computed tomography (CT) image, data of each pixel obtained as the result of the X-ray fluorography by the X-ray detection unit is subjected to a filtering process in a direction corresponding to a direction of one of two axes extending from the optical axis, the two axes are orthogonal to each other and both intersecting and orthogonal to the optical axis of the virtual circle, and the filtering process takes place at one or more of the plurality of positions along the circumference of the virtual circle.