Introduction to Gamma Irradiation

Gamma irradiation is a physical process that uses high-energy electromagnetic radiation (photons) to interact with matter. Unlike heat or chemical treatments, it is a “cold” process, meaning it can achieve its goals without significantly raising the temperature of the target material.

The process typically utilizes radioactive isotopes, most commonly Cobalt-60, which emit gamma rays (1.17 MeV and 1.33 MeV) as they decay. These gamma photons have high penetrative power, allowing them to pass through packaging and reach the interior of dense objects.

A common concern is that irradiated items become radioactive. They do not. Because the energy level of gamma rays from Cobalt-60 is below the threshold required to induce radioactivity in the nucleus of atoms, the treated material remains safe to handle or consume immediately after exposure.

Low-Dose Gamma Treatment

While industrial sterilization (like for medical devices) often requires high doses in the kilogray (kGy) range, low-dose irradiation—defined here as doses in the hundreds of grays (Gy)—is a precision tool used primarily in biology and agriculture. To put this in perspective: 1 gray (Gy) = 1 joule of energy absorbed per kilogram of matter.

Key Applications of Low-Dose Treatment include:

• Phytosanitary Measures: Used to prevent the movement of invasive pests. A dose of 150–400 Gy is often enough to “sterilize” insects (making them unable to reproduce) without damaging the quality of the fruit or vegetable they inhabit.
• Sprout Inhibition: Doses as low as 50–150 Gy are used on potatoes and onions to inhibit the biological processes that lead to sprouting, significantly extending shelf life.
• Mutation Breeding: In plant science, doses in the hundreds of grays are used to induce “controlled” DNA breaks. This encourages genetic variation, helping scientists develop crops that are more resistant to drought or disease.
• Blood Irradiation: In a medical context, doses around 25–50 Gy are used to treat blood products to prevent Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD) by inactivating donor T-lymphocytes.

Gamma Irradiator

A gamma irradiator is essentially a “radiation safe” designed to deliver precise doses of high-energy photons to a target. While industrial irradiators can be the size of a warehouse, research-scale units are self-contained cabinets that allow scientists to work with radiation without needing a room lined with several feet of concrete.

Please contact the Manager of Nuclear Services if you are interested in learning more about or using our gamma irradiator.