1. An X-ray diagnostic apparatus which obtains a plurality of images from different projection views of a patient by repeating imaging while rotating an X-ray tube around the patient, the apparatus comprising: a display on which images are sequentially displayed; control circuitry configured to stop sequential display of the images, and thereafter to control the display to display, as static images, to determine a first image and at least one second image among the plurality of images obtained from different projection views, and to determine a first point in the first image and a second point in the at least one second image; reconstruction region identification circuitry which calculates a three-dimensional point based on a first straight line and a second straight line, the first straight line connecting the first point and a point at which the X-ray tube is positioned when the first image is obtained, the second straight line connecting the second point and a point at which the X-ray tube is positioned when the second image is obtained, determines a reconstruction region, the reconstruction region being included in a region defined by a preset distance from the three-dimensional point and being less than a voxel matrix size of a region which can be reconstructed, and identifies an area corresponding to the reconstruction region in each of the plurality of images; and reconstruction circuitry which reconstructs a three-dimensional image using the area identified in each of the plurality of images by carrying out a backprojection operation.