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Typically, AAMI standards and technical information reports (TIRs) are static documents that do not permit any interaction with or customization for the user. Recently, AAMI ST/WG2 (Radiation Sterilization) developed a novel approach to the development of AAMI TIR76, which will codify a significant extension of the VDmax (maximal verification dose) approach to substantiating a minimum radiation sterilization dose.
TIR76 will include an interactive Web-based tool for calculating Method VDmaxSD-S values. This approach of including software as a service (SAAS) as part of a TIR is unique for AAMI. It breaks new ground by addressing the challenges of the usability of a method requiring detailed calculations and by preventing the need to include tables that are hundreds of pages long.
The extension of the methodology, termed Method VDmaxSD-S, allows for substantiating sterilization doses for sterility assurance level (SAL) values of 10-3, 10-4, and 10-5, in addition to 10-6.
TIR76 also will give users the ability to choose to irradiate 10, 30, or 90 product items in the verification dose experiment (VDE). The acceptance criterion for the outcome of the VDE has been aligned with that of Methods 1 and 2 of ANSI/AAMI/ISO 111372:20133 As with Methods 1 and 2, an outcome of two positive tests of sterility is acceptable for Method VDmaxSD-S; therefore, a confirmatory VDE is no longer required. The elimination of the performance of the confirmatory VDE streamlines the VDmaxSD-S methodology and allows for quicker reaction to VDE results.
In addition to the forthcoming TIR76, embodiments of Method VDmax have been codified in AAMI TIR27 (superseded), 11137-2, AAMI TIR33:2005,2 and ANSI/AAMI/ISO TIR13004:2013.3 Extension of the VDmax approach has evolved from a single "look-up table" for substantiating a 25-kGy sterilization dose in TIR27 to an interactive Web-based calculation tool for Method VDmaxSD-S values in TIR76.
Origin of the VDmax Approach
Methods 1 and 2 of 11137-2 are the original dose-setting methods, the foundations of which were laid in the "AAMI 60Co Dose Setting Intercompany Studies" performed in 1979. These methods are robust and have served the industry well since their publication in 1984. For both methods, 100 product items are required for irradiation in the VDE.
Method 1 uses bioburden information to set a sterilization dose; for a given average bioburden, verification dose and sterilization...