Correction: Hologic MammoSite ML Story

BEDFORD, Mass. (AP) — In a Sept. 1 story about Hologic Inc.'s MammoSite ML radiation system, The Associated Press erroneously described the workings of the device.

After a breast tumor is removed, a small balloon is placed into the area where the tumor was. A catheter is hooked up to the balloon and sends a small amount of radioactive material to the breast to kill any remaining tumor cells. The material stays there for 10 minutes at a time, twice per day, for five days. The radioactive material does not remain inside the body for the entire five days.