Abstract
Background ISO 11137-2006 (ISO 11137-2a 2006) provides a VDmax 15 method for substantiation of 15 kGy as radiation sterilisation dose (RSD) for health care products with a relatively low sample requirement. Moreover, the method is also valid for products in which the bioburden level is less than or equal to 1.5. In the literature, the bioburden level of processed bone allografts is extremely low. Similarly, the Queensland Bone Bank (QBB) usually recovers no viable organisms from processed bone allografts. Because bone allografts are treated as a type of health care product, the aim of this research was to substantiate 15 kGy as a RSD for frozen bone allografts at the QBB using method VDmax 15—ISO 11137-2: 2006 (ISO 11137-2e, Procedure for method VDmax 15 for multiple production batches. Sterilisation of health care products – radiation – part 2: establishing the sterilisation dose, 2006; ISO 11137-2f, Procedure for method VDmax 15 for a single production batch. Sterilisation of health care products – radiation – part 2: establishing the sterilisation dose, 2006). Materials 30 femoral heads, 40 milled bone allografts and 40 structural bone allografts manufactured according to QBB standard operating procedures were used. Method Estimated bioburdens for each bone allograft group were used to calculate the verification doses. Next, 10 samples per group were irradiated at the verification dose, sterility was tested and the number of positive tests of sterility recorded. If the number of positive samples was no more than 1, from the 10 tests carried out in each group, the verification was accepted and 15 kGy was substantiated as RSD for those bone allografts. Results The bioburdens in all three groups were 0, and therefore the verification doses were 0 kGy. Sterility tests of femoral heads and milled bones were all negative (no contamination), and there was one positive test of sterility in the structural bone allograft. Accordingly, the verification was accepted. Conclusion Using the ISO validated protocol, VDmax 15, 15 kGy was substantiated as RSD for frozen bone allografts manufactured at the QBB.
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Acknowledgements
This research was funded in part by the Queensland Bone Bank, Brisbane Private Hospital, and project grants from the Australian Institute of Nuclear Science and Engineering (AINSE), and National Health and Medical Research Council (ID 453624). Huynh Nguyen was supported by a Government Scholarship from the Ministry of Education and Training, Vietnam, and a Graduate School Scholarship from The University of Queensland. Research raw materials were supplied under agreement from Queensland Health Scientific Services and QHSS Human Ethics Approval 04-002/02(05). Special thanks to Dr. Wayne Monaghan (PAH) for microbiological advice; Mrs. Wendy Kelly (The University of Queensland), Mrs. Bronwyn Doig (QBB), and Mrs. Kym Tighe (QBB) for technical assistance, and Ms. Connie Banos and staff at the Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, for technical advice concerning irradiation of bone samples.
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Nguyen, H., Morgan, D.A.F., Sly, L.I. et al. Validation of 15 kGy as a radiation sterilisation dose for bone allografts manufactured at the Queensland Bone Bank: application of the VDmax 15 method. Cell Tissue Banking 9, 139–147 (2008). https://doi.org/10.1007/s10561-008-9064-5
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DOI: https://doi.org/10.1007/s10561-008-9064-5