Validating a Low Dose Gamma Irradiation Process for Sterilizing Allografts Using ISO 11137 Method 2B

This paper describes the validation of an allograft sterilization method specifically designed for the processing methods used at AlloSource in Centennial, CO. The methods used for this validation followed ISO Standard 11137, Method 2B. Three hundred allografts, collected from three defined production batches were dosed using a series of five incremental doses, beginning at 1 kGy and increasing by 1 kGy until 5 kGy was achieved. Following sterilization dosing, each allograft test article was analyzed using a sterility test to identify any viable microorganisms. The number of positive sterility samples was used to calculate the verification dose (1.27 kGy), which was then verified by an additional batch of 100 allografts. The results from this validation indicate that sterility (10⁻⁶ SAL) on human allograft tissue using gamma ⁶⁰Co radiation can be achieved when a dose of at least 9.2 kGy is employed.