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Maximum Dose Validation
Maximum Dose Determination
Definition - Maximum dose determination is the establishment of a maximum level of radiation to which the product is to be exposed and which will not effect the form, fit, or function of the product. Typically, the maximum dose is at least two times the minimum sterilization dose. This provides an adequate processing window for electron beam sterilization. The maximum dose is established by the irradiation of representative samples of the product at various dose levels to determine the dose level at which form, fit, or function is compromised. The testing which the product should undergo to determine the impact of irradiation at various dose levels typically falls into the following categories:
- Form - Can the device still be marketed if there is a color change or change in the device itself? Will such a change inhibit the capability to market and sell the device?
- Fit - Is the presentation of the product in either the clinical and/or hospital setting compromised with regard to sterility? Is the packaging able to maintain a sterile barrier?
- Function - Is product performance compromised relative to strength, embrittlement, discoloration and other physical or cosmetic properties?
Procedure - Obtain representative samples of each type or category of device and expose them to a radiation dose equal to, or in excess of, two times the minimum sterilization dose. Typically, BeamOne customers choose three doses in increments of 5 or 10 kilogray above the doubled minimum dose. Several individual product units are exposed to each dose level. Upon receipt from the irradiator, perform the identified tests and/or evaluations to determine whether or not form, fit or function has been changed within the device. Once completed, and the maximum dose established, any changes to the materials and/or manufacturing process should be evaluated with regard to their potential impact on the established maximum dose.
It should be noted that, in most cases, if a material has been qualified for gamma sterilization, the same dose applied by electron beam can be used as a starting point, since electron beam causes significantly less oxidative degradation than gamma rays. This qualification approach is both quick and very cost-effective.
Grouping of Products - Grouping of products for maximum dose establishment is typically done based upon the types of materials used in manufacturing, the manufacturing process itself, and those specific components which may undergo certain stresses during their end use. The rationale for the grouping of products should be documented and maintained.