X-ray sources including an electron source, an adjustment means for adjusting an orientation of the electron beam generated by the electron source, a focusing means configured to focus the electron beam in accordance with a focusing setting, a beam orientation sensor arranged to generate a signal indicating an orientation of the electron beam relative to a target position, and a controller that is operably connected to the focusing means, the beam orientation sensor and the adjustment means. Also, X-ray sources including a target orientation sensor and a target adjustment means, wherein the controller is configured to cause the beam adjustment means and/or target adjustment means to adjust the relative orientation between the electron beam and the target.