Quarterly Gamma Dose Audit Question

[IntegrityandQuality]

This pertains to VDmax25 gamma sterilization. When a test lab performs the gamma quarterly dose audit is it necessary to use the same sterilizer as is used for production material? Dose mapping and setting of dose has previously been done using the production sterilizer. The quarterly dose audit includes dosimeters with the product. Can you point to the section of ISO 11137-x that supports your response? Thanks in advance.

 

[Jimmy the Brit]

Re: Quarterly Gamma Dose Audit Question Mmmm

Hi Integrity&Quality,

I don't see how it is possible to use the same facility unless you are using a small "mom & pop" irradiator. Most industrial irradiators have different source chambers, one set using the standard matrix in order to deliver the high intensity field necessary for sterilization and an other usually with the cobalt rod under water to allow a wide range of lower test doses. When you confirm your verification dose the rods are raised long enough to give a specific dose, significantly lower than your sterilization dose (as required by 11137)

I have never heard of a mainstream irradiator who is prepared to empty their line, change the rod configuration, then start up the line with dunnage boxes (to simulate the dose absorption from a full track) before running in a validation load, running the irradiator chamber empty, changing the rod config blah, blah.. The cost would be prohibitive and there is no point. The beauty of radiation sterilization is that dose-is-dose, as long as the rods are made up of the same nuclide the decay energy will be the same whether you perform the test in Siberia or Timbuktu. This is why gamma validations are entirely transferable, as long as the irradiator has validated their field properly and you can show proper change control of densities, materials, bioburden etc...

I don't have a copy of the standard with me at the moment, but I am certain it does not require you to use the same chamber - I know I don't!

Jimmy

 

[Chris Auditor]

Re: Quarterly Gamma Dose Audit Question Mmmm

Take a look at section 8.4 of 11137-1:2006. It discusses the requirements for transference of dose.

 

[Kees Fremery]

Re: Quarterly Gamma Dose Audit Question Mmmm

Chris is right and to keep it easy: when you are using a gamma source it is permitted to transfer from one irradiator to another. Using e-beam there are some restrictions, depending on the presence of water in your product.

 

[IntegrityandQuality]

Kees, Chris and Jimmy: Thanks for the feedback. It confirms what others were saying...hard to break from my EtO background. Thanks again for taking the time to respond.