In order to provide an X-ray CT apparatus and an image reconstruction method that can determine a movement phase to be used for generating diagnostic images with a small number of operations and can acquire diagnostic images in a short time while reducing a burden on an operator in scanning in which the target is a moving site, an image processing device 403 of an X-ray CT apparatus 1 obtains movement information of a diagnostic site (such as the heart), determines phase selection positions p1, p2, and . . . so that the operator selects an arbitrary movement phase based on the acquired movement information, and reconstructs selection images 80 in a plurality of movement phases (for example, 75% to 95% or the like) for each of the determined phase selection positions p1, p2, and . . . using scan data before presentation.

Provided herein is a radiography apparatus including an X-ray source configured to irradiate a subject radiation, and a sensing module configured to sense the radiation having passed through the subject, wherein the X-ray source includes a cathode electrode comprising an electric field emitting source configured to emit electrons, an anode electrode disposed opposite to the cathode electrode and configured to use the electrons to generate the radiation, and a current control unit connected to the cathode electrode to control an amount of the electrons.

A radiation imaging system includes an imaging unit, a detection unit, a change determination unit and a control unit. The imaging unit emits radiation and images a dynamic state of a subject, thereby taking a plurality of frame images of the dynamic state of the subject. The detection unit detects the dynamic state of the subject being imaged and generates detection information on the dynamic state. The change determination unit determines whether change of the dynamic state being imaged is within a predetermined range based on the generated detection information. The control unit controls capturing of the taken frame images according to a result of the determination of the change determination unit.