Glossary

A List of Commonly Used Terms in Blood Banking

Irradiation

Modification to a blood product in which cellular blood products are exposed to a specified amount of either gamma rays (most commonly), x-rays, or ultraviolet B rays (outside of the U.S.). Irradiation is performed solely to prevent transfusion-associated graft vs. host disease, a horrible complication of transfusion that is far better prevented than diagnosed. In order for a product to be called “irradiated” in the U.S., 25 Gray (Gy) of irradiation is targeted to the center of the irradiation chamber, with the equipment calibrated to deliver no less than 15 Gy to any part of the bag (the dose is higher in other countries, up to a maximum of 50 Gy). This procedure can be done either at the collecting facility or transfusion service. Many facilities have stand-alone cesium-based irradiators that they use to perform the procedure. Stand-alone X-ray irradiators have come on the scene in recent years, and offer fewer administrative and regulatory headaches. A number of facilities utilize the linear accelerators used in radiation oncology therapy to irradiate blood products.

The FDA says that an irradiated product expires 28 days from irradiation OR the product’s regular expiration date, whichever comes first. Obviously, irradiating a unit of platelets has no effect whatsoever on that unit’s expiration time (since platelets only have a five day shelf-life anyway). See the “Why do we irradiate?” video for more information.

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