The irradiation intensity distribution of the X-ray bundle that becomes non-uniform due to the heel effect is made uniform to prevent the subject from being exposed more than necessary. Further, the image quality of the image data by the X-ray CT apparatus is made uniform and favorable in the body axis direction. When irradiating a subject with an X-ray bundle generated at the anode by irradiating a thermoelectron beam bundle from the cathode to the anode, the X-ray bundle spreads from the anode to the body width direction of the subject, and is substantially reduced in the body axis direction by the heel effect. A heel effect correction filter having a uniform X-ray intensity angle distribution that is non-uniform in the body axis direction of a subject in an X-ray bundle irradiation region that is formed in a fan shape. This can be obtained by a predetermined calculation formula.
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