"There are three sources of radiation approved for use on foods. Gamma rays are emitted from radioactive forms of the element cobalt (Cobalt 60) or of the element cesium (Cesium 137). Gamma radiation is used routinely to sterilize medical, dental, and household products and is also used for the radiation treatment of cancer. X-rays are produced by reflecting a high-energy stream of electrons off a target substance, usually one of the heavy metals, into food. X-rays are also widely used in medicine and industry to produce images of internal structures. Electron beam, or e-beam, is similar to X-rays and is a stream of high-energy electrons propelled from an electron accelerator into food."