An x-ray tube (24) includes an anode (42) defining a target. A cathode assembly (40) is in operative relationship with the anode to produce x-rays (56). An evacuated envelope (35) encloses the anode and cathode. The evacuated envelope includes a metal frame portion (39). The material comprising the metal frame portion has a backscatter coefficient. An x-ray transmissive window (41) is joined in a vacuum tight manner to the metal frame portion of the evacuated envelope. The material comprising the x-ray transmissive window has a backscatter coefficient. A backscatter layer (90) is deposited on the x-ray transmissive window and the metal frame portion of the evacuated envelope around the x-ray transmissive window. The backscatter layer has a backscatter coefficient greater than the backscatter coefficient of both of the window and the metal frame.