cross section that was reduced on account of interference and 18 b denotes an electron beam cross section that was enlarged on account of interference the x ray tube 39 s focal point cross section depending only on the cross section of the target element 6 and latter being constant fluctuations in electron beam cross section do not affect focal point cross section as long as the target element 6 is irradiated over its entire surface by the electron beam as shown by fig6 the same considerations also apply to a lateral shift of the electron beam into a position 18 c because the target element 6 is irradiated by the electron beam over its entire surface also in this position as shown by fig7 even changes in electron beam cross section do not affect the focal point cross section as long as the target element 6 remains irradiated over its full surface fig7 shows merely by way of example two distorted electron beam cross sections 18 d and 18 e as the focal point cross section depends solely on the cross section of the target element 6 which is constant and fixed in place cross sectional changes of the electron beam do not degrade x ray image quality when using a target 2 of the invention in an imaging x ray tube as can be seen by comparing fig5 through 7 cross sectional changes and shifting of the electron beam do.