Abstract: In one embodiment, a method includes applying an output of a substantially monochromatic x-ray beam source to a target tissue along a first path, tuning the output of the substantially monochromatic x-ray beam source, and applying an output of a substantially monochromatic x-ray beam source to a target tissue along a second path different from the first path. The energy of the output of the substantially monochromatic x-ray beam source at the target tissue substantially corresponds to a binding energy level of an electron shell in an atom within the target tissue along the first path. The tuning tunes the substantially monochromatic x-ray beam source such that an energy of the output of the substantially monochromatic x-ray beam source at the target tissue along the second path substantially corresponds to a binding energy level of an electron shell in an atom within the target tissue.

Abstract: In embodiments of the invention, a radiosensitizer or other agent is relatively uniformly accumulated in the cells of a tumor. An external monochromatic x-ray beam, which is tuned to a predetermined energy level associated with k-edge effects in the agent, is then directed to the tumor. The monochromatic x-ray beam activates the release of additional localized radiation from the agent. The additional radiation destroys the DNA of at least some tumor cells, making those tumor cells incapable of reproduction and repair. In embodiments of the invention, a single monochromatic x-ray beam source is used for both imaging and radiotherapy.