A method for controlling an x-ray source comprises generating an electron beam for striking the target to generate x-rays and steering the electron beam to a desired location on the target using a first and a second steering system distributed along a flight tube. In this way, the beam can be steering to the desired location while also passing through the center of a focusing lens to maintain optimal beam characteristics. Also possible is scanning the electron beam over the target to find a fiducial mark. Then, a desired location can be found as an offset from this mark.