X-RAY CT APPARATUS AND TOMOGRAPHY METHOD

In order to provide an X-ray CT apparatus with little image quality degradation even though a tube current value of the X-ray tube is suppressed, an X-ray CT apparatus of the present invention includes: a system controller that calculates a tube current value of an X-ray tube based on a successive approximation process condition selected from a plurality of successive approximation process conditions and input a scanning condition and/or a reconstruction condition and that performs scanning based on the calculated tube current value of the X-ray tube; and an image reconstruction device that reconstructs a tomographic image of an object, based on the selected successive approximation process condition and the reconstruction condition, from an amount of transmitted X-rays detected by an X-ray detector after being emitted from an X-ray source to the object based on the calculated tube current value of the X-ray tube and being transmitted through the object.