Processing Classes in Radiation Sterilization: Advantages, Requirements, and Limitations
As medical device portfolios grow, each addition initially requires a separate qualification process for Radiation sterilization: new part numbers, new package sizes, and new variants of existing products. As the number of items increases, so does the effort required for qualification and documentation. Grouping suitable products into processing classes can reduce the administrative burden.
Key takeaways at a glance
- Processing classes group multiple medical devices that can be sterilized under the same irradiation conditions into a common release and documentation process.
- Prerequisites include comparable physical parameters such as density, weight, dimensions, and product count, as well as a suitable packing scheme and a uniform dose range.
- Suitable products within a portfolio can be grouped into a single processing class, streamlining administration.
- Not every product in a portfolio needs to fit into a processing class. Deviating outliers can be qualified separately as needed.
- Revalidating an existing processing class is generally easier than a complete new qualification.
What are processing classes?
Processing classes are groups of products that can be sterilized under the same irradiation conditions and released together.
At BGS, we work closely with our customers during a preliminary assessment to establish the foundation for each processing class. Factors taken into account include:
- dimensions and weight of the shipping carton,
- the product’s design,
- the arrangement of the products in the carton,
- the packing scheme,
- the dose range, and
- the handling of mixed pallets and partially loaded pallets.
Within a portfolio, product variants may differ, for example, in terms of size, weight, or density. To define a processing class, the relevant parameters and their permissible ranges are considered. If a product deviates significantly from the rest of the portfolio in terms of density, weight, or construction, it is deliberately excluded and qualified separately. Please note: Processing classes are always defined on a customer-specific basis. Products from different manufacturers are not grouped together.
Good to know
The ISO 11137 series of standards governs the fundamental requirements for validation, dose determination, and process monitoring in radiation sterilization. You can find an overview here: ISO 11137: An Overview of the Procedural Standard.
What are the advantages of processing classes?
When products are qualified and managed individually, the administrative effort increases with the number of items. Processing classes reduce this burden, as a best-case and a worst-case product cover the full range of the parameters described above (such as carton size, weight, and density). This simplifies ordering, helps prevent data-entry errors, and streamlines process documentation.
The advantages are particularly evident when changes are made to the product portfolio. New products can be added to the class without having to repeat the entire qualification process. Instead, a mathematical assessment helps determine whether the product meets the class’s requirements. If so, the item is added to the processing class. It’s also possible to remove individual products from an existing processing class without fundamentally affecting the qualification of the remaining products.
In short: Once set up properly, the processing class saves time and effort with every portfolio change.
Would you like to see how processing classes are established in practice? In this video, Barbara Schmitz and Annett Heilmann explain how a preliminary assessment is typically conducted, what matters when grouping products, and in which cases a processing class is not technically feasible.
Note: The webinar is held in German. English subtitles available.
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More InformationLimitations and prerequisites
Not every product portfolio is suitable for this approach. Physical parameters such as density, weight, dimensions, and product count are crucial; these must be comparable across all products in a class.
If products differ fundamentally in their design – for example, a compact metal implant and a small plastic connector – they cannot be technically grouped into a single class. In such cases, separate qualification is required. Products should therefore only be grouped into a single processing class if the technical requirements are met.
Good to know
Radiation can alter the properties of some plastics, causing discoloration or embrittlement. Find out here what manufacturers should consider early on when selecting materials: Radiation Sterilization: The 5 Most Common Material Mistakes.
What are the differences between gamma and E-Beam sterilization?
With gamma irradiation, the irradiation unit is typically the entire pallet. Partially loaded pallets can generally be accommodated here, as can mixed pallets containing different products of the same class. To define a class, manufacturers often start by working with sample products. As these test units may be irradiated multiple times, they can receive a correspondingly high cumulative dose and are subsequently no longer suitable for sale.
In E-Beam sterilization, on the other hand, the individual shipping carton is normally the irradiation unit; less commonly, it may be the individual product or the tray. This is because the limited range of the electron beam does not allow for larger units. Unlike with gamma irradiation, partially loaded cartons cannot be accommodated here – they must be fully loaded. Due to the limited penetration depth, particular attention must be paid to the arrangement of the products in the shipping carton as well as the number of irradiation passes required.
In both cases, the same principle applies to documentation: The individual items within a processing class are qualified under a common technical report.
Revalidate the processing class instead of requalifying it
If the product portfolio changes within an existing processing class, a complete requalification is usually not required. For medical devices, revalidation may require less effort than complete requalification since the fundamental process conditions of the processing class are already established.
However, this requires that changes to the product portfolio be documented continuously and carefully. Especially for extensive classes, the listed products should be reviewed regularly, even if no changes have occurred in the meantime. The manufacturer remains responsible for ensuring every individual product can be clearly traced.
Conclusion: Who can benefit from processing classes?
Processing classes are particularly suitable for product portfolios in which multiple items can be processed under comparable irradiation conditions.
Processing classes group products with comparable physical parameters, packing schemes, and dose ranges under a common release. This reduces administrative overhead – from documentation and the ordering process to revalidation. Individual outliers in the portfolio are specifically qualified separately, while non-compliant products can be qualified separately.
Those who wish to delve deeper into the normative foundations of validation will find answers in the webinar “Radiation Sterilization of Medical Devices: Normative Developments in Validation” (english subtitles available).