Radiation sterilization—computer evaluation of ISO 11137 dose setting method 1 and ISO/TR 13409 method for substantiation of 25 kGy

• Published in: Radiation physics and chemistry (Oxford, England : 1993) Vol. 54; no. 1; pp. 83 - 94
• Main Authors: Aoshuang, Yan, Tallentire, Alan
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1999; Elsevier
• Subjects: Applied microbiology; Biological and medical sciences; Computer applications; Dosimetry; Fundamental and applied biological sciences. Psychology; Ionizing radiation; Microbiology; Microorganisms; Miscellaneous; Evaluation; Choice; Microbiology; Verification; Radiation dose; Ionizing irradiation; Microorganism resistance; Simulation; Distribution; Sterilization; ISO standard; Hygiene; Computer aid
• ISSN: 0969-806X; 1879-0895
• DOI: 10.1016/S0969-806X(98)00203-5

Computer evaluations of ISO dose setting/substantiation methods, involving challenging them with hypothetical microbial populations of various sizes and resistances, have shown the methods to be generally reliable and safe. However, the ability to Method 1 to detect at a sterility assurance level (SAL) of 10 −2 the occurrence of populations of resistances greater than that of the standard distribution of resistances (SDR) decreases with decreasing bioburden level. The ISO method for substantiation of 25 kGy operates correctly for populations of high bioburden levels whose resistances are either greater or lower than that of the SDR. At low bioburden levels, however, the method can provide “incorrect” results—substantiation is rejected even though an SAL of 10 −6 or less is obtained at 25 kGy. This occurs because there is no direct relationship between the outcome of the verification dose experiment and attainment at 25 kGy of an SAL of 10 −6.