The subject invention pertains to a method and apparatus for generation and/or delivery of x-ray irradiation. The subject invention can be used to deliver x-ray irradiation to an artery in order to prevent restenosis in the artery. For example, a short pulse laser generated ionizing dose of x-ray irradiation can be effectively delivered to the arterial wall using hollow waveguides. The delivery of such a dose can help to prevent restenosis. The use of short pulse x-rays can allow energy to be precisely delivered, and can reduce diffusion of the energy to nearby normal tissue during the exposure. The arterial walls can be irradiated from a cylindrical or conical symmetric mirrored reflective end tip mounted on the end of a hollow waveguide. The subject invention also pertains to a method and apparatus for delivery of x-ray radiation with respect to medical therapies such as tumor necrosis.