Abstract: A method of treating diseased tissue in a patient, the diseased tissue being proximate a hardened previously implanted bone cement including relatively high atomic number elements in a patient. The method includes generating a photon beam and directing the generated photon beam into the patient in a direction such that at least a portion of the photon beam impinges on the hardened bone cement and generates Compton interaction knock-out electrons from the high atomic number elements included in the hardened bone cement as a result of interaction of the at least a portion of the photon beam with the bone cement, wherein the direction of the photon beam is such that the at least a portion of the photon beam impinges on the hardened bone cement so that at least some of the Compton interaction knock-out electrons impinge upon the diseased tissue.