Intraoperative radiation therapy (IORT) is an intensive radiation treatment that's administered during surgery.

IORT allows direct radiation to the target area while sparing normal surrounding tissue. IORT is used to treat cancers that are difficult to remove during surgery and when there is a concern that microscopic amounts of cancer may remain.

The type of IORT most commonly used at Mayo Clinic is also called intraoperative electron radiation therapy. IORT is often combined with conventional radiation therapy, which is usually administered before surgery.

IORT allows higher effective doses of radiation to be used compared with conventional radiation therapy. It's not always possible to use very high doses during conventional radiation therapy, since sensitive organs could be nearby. IORT also allows doctors to temporarily move nearby organs or shield them from radiation exposure.

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