A system and method for generating X-rays comprising a waveguide having a cavity extending therethrough, a first sidewall, and a second sidewall opposite the first sidewall, the second sidewall having an opening extending therethrough forming or including a target therein. An electron emitter coupled to an inner surface of the first sidewall for emitting electrons into the cavity, microwaves coupled into the cavity generating an electric field for accelerating the electrons through the cavity and toward the target in the opening of the second sidewall for generating X-rays.