Brachytherapy apparatus

The present disclosure provides a brachytherapy apparatus that delivers a low dose, partial breast irradiation treatment for post-lumpectomy patients via introduction of a catheter-like device through a cannula. The apparatus may be introduced post-surgically with local anesthesia under image guidance into the previous excision site and into a cavity by a surgeon. The brachytherapy apparatus includes a seed containment device configured to contain a plurality of low-dose radioactive seeds therein. The seed containment device may be one or more thin-walled tubes. The apparatus is further configured to expand so that at least a portion of the seed containment device is positioned against the remaining tissue and the plurality of radioactive seeds are disposed at the perimeter of the seed containment device. Also described are various clamps for the apparatus, and sleeves for adjusting the size of the device to fit a cavity when the apparatus is in use.