An X-ray tube according to the present invention comprises an anode and a cathode comprising an emission portion for emitting an electron beam. The emission portion is configured to irradiate a target surface of the anode with electrons to cause the anode to emit X-rays. A window is arranged at an end of the X-ray tube, to allow X-rays to exit the X-ray tube. The target surface of the anode is inclined at an oblique angle with respect to a longitudinal axis, wherein the longitudinal axis passes through the end of the X-ray tube.