Today, only 12 percent of breast cancers in the United States are treated with accelerated partial breast irradiation (APBI). Breast brachytherapy is a form of APBI that delivers radiation dose from within the breast and tumor cavity using a tiny radioactive pellet of iridium-192. The clinical benefits of this targeted approach to radiation delivery are clear — reduced radiation exposure to healthy tissue, better cosmetic results and fewer side effects, and allowing more future treatment options in the event of a recurrence or new primary cancer.