Patent ID: 7184514

Claim:
An X-ray CT apparatus, comprising: an X-ray tube including (1) a cathode configured to emit a heat electron, (2) a target, including a plurality of areas where target angles are different in a rotational direction, which the heat electron collides with, and (3) a rotation mechanism configured to rotate the target in the rotational direction; an X-ray detector configured to detect an X-ray irradiated from the X-ray tube; a reconstruction unit configured to reconstruct an X-ray image based on data detected by the X-ray detector, said reconstruction unit configured to perform image reconstruction based on a total dose distribution received by said X-ray detector from irradiation by at least two of the target areas having different target angles; a position detector configured to detect a rotation position of the target; and an emission controller configured to control an emission of the heat electron such that the heat electron collides with the target except at a borderline positioned between the areas, wherein the emission controller comprises: a grid configured to generate a magnetic field in such a direction that the emission of the heat electron is blocked; and a grid controller configured to impress a negative bias voltage on the grid in a predetermined timing to control a timing of the emission of the heat electron.