An x-ray tube includes a cathode which supplies electrons that bombard a target material to produce x-rays. The target is supported on a rotating anode that includes fins covered with a high emissivity material. An envelope surrounds these elements and provides a vacuum chamber in which they operate. A receptor is mounted to the envelope and includes fins which mate with the anode fins to enhance the radiation of heat from the rotating anode. A cooling liquid is pumped through the receptor.