An X-Ray tube is provided. The X-Ray tube includes a frame structure surrounding at least a portion of an electron beam source and an electron beam target. The frame structure has a cooling system integrated therein. The cooling system includes at least one air/fin layer; and a sub-cooled working fluid in thermal contact with the at least one air/fin layer, the sub-cooled working fluid being adapted to undergo a phase change in response to heat introduced to the frame structure by one or more of the electron beam source and the electron beam target, wherein the phase change facilitates transfer of the heat to the at least one air/fin layer.