Intraoperative radiation therapy

Radiation therapy has been used to treat cancers for over one hundred years. Over the last century our understanding of the biology of radiation exposure as well as our ability to safely deliver extraordinarily high doses of radiation to specific targets has led to its routine use in both curative and palliative settings for most solid tumors. External radiation beam techniques invariably involve irradiating normal tissues that are located between the radiation source and the intended target. High-energy linear accelerators have greatly reduced skin and subcutaneous radiation-induced injury; however, radiation tolerances of organs adjacent to the target do frequently limit the total amount of radiation that can be used. Intraoperative radiation therapy (IORT) can be delivered in a number of ways, with the ultimate intent of minimizing normal tissue exposure to potentially harmful doses of radiation. Multiple IORT delivery modalities are now available, all of which present potential advantages and disadvantages over other methods of treatment. The specific techniques, radiobiologic considerations, and clinical uses of IORT will be described.