Gamma Irradiation Processing

The gamma sterilization process uses Cobalt 60 radiation to kill microorganisms on a variety of different products. Processing with gamma irradiation yields quick turnaround time, easily penetrating packaging and product, and is ideal for many types of materials.

What is Gamma Irradiation?

Cobalt-Glow-4The radioisotope cobalt 60 is the energy source for use in gamma irradiation sterilization with the irradiation process taking place in a specially designed cell. A key characteristic of gamma irradiation is the high penetration capability. This enables moderately dense or sealed products to be processed with relative ease and facilitates treatment of palletized product. The unit of absorbed dose is kiloGray, expressed as kGy. The absorbed dose is determined by product density, pack size, dose rate, exposure time and to some degree by plant design.

What is Gamma Irradiation Used For?

The gamma process can effectively sterilize a wide variety of products composed of different materials, with varying densities, configurations and orientations. Some examples of products processed include:

  • Medical devices
  • Pharmaceuticals
  • Combination drug/device products
  • Animal husbandry
  • Archives
  • Cosmetics and toiletries
  • Horticultural supplies
  • Packaging

For a list of products commonly treated by gamma irradiation, please see Technical Tip # 4

Gamma Irradiation Sterilization for Medical Devices

The treatment of medical devices by gamma processing has been one of the principal methods of sterilization in the healthcare industry since the introduction of the concept of single use, sterile, disposable medical devices in the 1960s.

This simple, proven process is safe, reliable, and highly effective at treating single-use medical devices. With the ability to penetrate products while sealed in their final packaging, gamma irradiation supports the manufacturing and distribution process by facilitating final packaged product as well as raw materials, whilst still ensuring full sterility of the product.

What is a typical gamma processing cycle?

  • The product arrives on a truck and is unloaded at the processing facility
  • The product is received by lot and product code that is entered into the STERIS Applied Sterilization Technologies (AST) operations management system, which provides for run generation, scheduling, processing, certification and release of product for shipment
  • The product is loaded into the processing container per established configurations, dosimeters are placed, and the product is exposed to the radiation field (Cobalt 60 source rack)
  • Dosimeters are analyzed after gamma irradiation of the product is complete, to confirm that the required dose has been delivered
  • All documentation and processing history records are reviewed, and if they are acceptable and Customer specifications are met, the product is released and shipped for use or further distribution

View our TechTeam Resources to learn more about the gamma irradiation process.

Gamma Irradiation Summary

Gamma Icon


Gamma irradiation exposes products to a Cobalt 60 radiation field

Technology Variables

  • Time in Cell
  • Isotope Load
  • Product Conveyance

Product Considerations

    • Compatible with most materials
    • Good penetration on dense products

Possible Effects


On certain materials, embrittlement, discoloration, change in viscosity due to irradiation

Exposure Time


    • (time varies based on dose requirements)


As a global leading sterilization and contamination control specialist, STERIS AST has over 40 years experience in providing safe and effective gamma irradiation sterilization.

Contact our team of experts to find out more about our Global Contract Sterilization Services