Some embodiments include a system, comprising: a plurality of x-ray sources, each x-ray source including: an electron source configured to generate an electron beam; and a target configured to receive the electron beam and convert the electron beam into an x-ray beam; wherein: at first x-ray source of the x-ray sources is different from a second x-ray source of the x-ray sources; and the targets of the x-ray sources are part of a linear target.