An all metal and ceramic high vacuum rotary anode X-ray tube adapted for mounting on a gantry of a rotational type CT scanner. The evacuated region where X-rays are generated is maintained at about 10.sup.-7 Torr. Vacuum sealing about the rotating shaft of the anode is provided by a magnetic fluid. No bearings are utilized within the evacuated region. Large, long wearing ball bearings that transmit rotation through the vacuum seal are provided about the shaft outside of the high vacuum region where conventional lubricants may be applied. Circulating coolant is applied internally through the anode assuring continual operation of the tube without the need for frequent cool-down waits.