Mammosite radiation therapy is a form of internal radiation treatment that is designed to eradicate cancerous cells possibly left behind after a lumpectomy operation. Sometimes referred to as partial-breast radiation or brachytherapy, the MammoSite system employs a specially designed catheter with a small balloon at the very end. The balloon is placed in the space where the mass was removed, and filled via the catheter with a fluid that helps keep it in place for approximately one week. During that week, the patient receives radiation therapy twice per day via a less-than-10-minute procedure in which a radioactive seed is injected into the center of the balloon. Following five days of treatment, the balloon can be removed. This targeted method of delivering radiation avoids unnecessary harm to nearby, healthy tissue and reduces the patient’s time spent receiving therapy. However, only specific breast cancer patients are considered candidates for this treatment.