Radiation therapy is administered to many breast-cancer patients following a lumpectomy. The goal is to reduce the risk of cancer recurrence by destroying any cancer cells in the tumor cavity. Traditionally whole-breast irradiation uses a radiation source outside the body to treat the cancer site, usually involving daily treatments for six days per week over a six- to seven-week period. Many breast cancer patients are appropriate candidates for an alternative to whole-breast radiation treatment known as partial-breast irradiation. Breast brachytherapy is a partial-breast irradiation technique that delivers radiation to tissue surrounding the lumpectomy cavity rather than to the entire breast. By targeting treatment from inside the breast, radiation treatment can be completed in five days, allowing patients to return more quickly to their day-to-day.