ABSTRACT
RADIATION sterilization is exposure of a product to high-energy electrons or high-energy electromagnetic radiation in the form of X-rays or
gamma rays in a controlled and safe manner. Particle accelerators are used as the source of high-energy electrons, and these same accelerators can be used to generate X-rays in the form of bremsstrahlung radiation by placing a high atomic number conversion target in the electron beam. Radioisotopes of cobalt and cesium are the principal sources of gamma rays for this efficacious method of sterilization. High-energy electrons, bremsstrahlung radiation and gamma rays penetrate deeply into most products, even when they are in their final packaged state, thus ensuring that all elements of the product have been effectively sterilized. Radiation sterilization is a mature industry that traces the existence of the first commercially viable irradiator facilities to the late 1950s [1]. Today, high-power electron beam machines and gamma irradiators containing millions of curies of isotope are capable of sterilizing millions of cubic feet of product per year. It is perhaps the efficacy of the process and the relative simplicity of treatment that attracts many to select this method of sterilization. Use of particle accelerators to generate bremsstrah~ lung radiation is a more recent development in the field of radiation sterilization [2,3]. With the availability of robust and very high-power electron beam accelerators, bremsstrahlung irradiators began to be brought on line in the late 1980s to service the radiation sterilization industry [ 4].
