An X-ray tube device capable of preventing a holder holding a bearing from suffering damage, and an X-ray CT apparatus including the X-ray tube device are provided. The X-ray tube device includes: a cathode that produces an electron beam; an anode that produces X rays upon irradiation with the electron beam; a rotating portion that supports and rotates the anode; bearings that are placed at a predetermined distance from each other in a direction of a rotation axis of the rotating portion, each of the bearings having an outer ring and an inner ring between which rolling elements are sandwiched; and a holder that holds the outer rings. The holder has an inner wall that is spaced from an edge of the outer ring.

According to one embodiment, a rotating anode X-ray tube includes a fixed shaft, a rotor, a lubricant, target, and a supporting member. The fixed shaft includes a small-diameter portion provided with a first radial bearing surface including first grooved surfaces, and a large-diameter portion provided with a second radial bearing surface including second grooved surfaces. The rotor includes a third radial bearing surface. The lubricant is filled in a gap between the fixed shaft and the rotor, and drawn by the first and second grooved surfaces.

In some embodiments, a system may include an X-ray tube assembly having an anode disk assembly. The system may include a motor configured to rotate the anode disk assembly. The system may include one or more pumps configured to draw a vacuum in the X-ray tube assembly. The system may include a cooling system configured to cool the anode disk assembly. In some embodiments, a method may include drawing a vacuum in an X-ray tube assembly with one or more pumps. The method may include rotating an anode disk assembly of the X-ray tube assembly. The method may include cooling the anode disk assembly with a cooling system. The method may include activating a power supply to produce an electron beam. The electron beam may interact with an X-ray generating layer of the anode disk assembly to produce an X-ray beam oriented to impinge on a sample.