<qa>  What is the MammoSite applicator designed to deliver internal radiation therapy?Data relevant to the evaluation of the efficacy and safety of the MammoSite RTS system in providing radiation therapy to patients with DCIS will be collected. The MammoSite is a radionuclide applicator designed to deliver internal radiation therapy brachytherapy in patients with breast tumors following breast tumor resection surgery lumpectomy. 