The methods of selection of the sterilization dose rely on data derived from the inactivation of the microbial population in its natural state and are based on a probability model for the inactivation of microbial populations. The selection depends upon experimental verification that the response to radiation of the product bioburden is greater than that of a microbial population having a standard resistance. The contention that the model population presents a more severe challenge to the radiation sterilization process than the natural microflora normally present on or in products to be sterilized. The basic requirements and guidance for validation of a radiation sterilization process can be found in ANSI/AAMI/ISO 11137: 1994, Sterilization of health care products Radiation sterilization and in EN 552, Sterilization of medical devices—Validation and routine control of sterilization by irradiation. A documented calibration program for gamma irradiators includes irradiation cycle timers or conveyor speed, weighing equipment, and the dosimetry system.