Cobalt 60 Irradiation Sterilisation
The radiation dose received by a product passing through a Cobalt 60 irradiation facility is defined by five parameters:
- The strength (activity) of the source.
- The density of the product
- The time of exposure
- The distance of the product from the source.
- The density of any product between the source and the product in question.
The control method utilised by Swann-Morton is based on both time of exposure and the load scheduling of products with different density.
Product is moved through the irradiation facility by product carriers suspended from an overhead conveyor rail. The Cobalt 60 source is enclosed by a concrete shield approximately 2 metres thick and constructed from high density poured concrete extending to all sides, above and below the source and the product being irradiated.
To monitor the level of sterilisation red Perspex dosimeters are attached to products being irradiated on a routine basis to ensure that the process is fully under control at all times. Swann-Morton (Services) Limited measure the radiation induced change in optical density of red Perspex dosimeters. Each batch of dosimeters is calibrated by the National Physical Laboratory.
Re-sterilisation of Swann-Morton surgical blades included in theatre packs.Swann-Morton surgical blades supplied as single use sterile medical devices that are used in theatre packs are capable of withstanding the normal temperatures and pressures used in autoclave sterilisation cycles without damage to the product during one cycle.
However, repeated autoclaving leads to a breakdown of the seal, compromising the sterility of the product. It is the policy of Swann-Morton Limited to recommend that surgical blades are discarded after one autoclave cycle, regardless of whether or not they have been used.