A method for brachytherapy in a lumpectomy cavity of a breast including, positioning a distal end of a brachytherapy device within the cavity, expanding an expandable surface portion located between proximal and distal ends of the device within the cavity, the source lumen tubes defining a curved configuration within the cavity; and positioning a source of radiation sequentially within one or more source lumens of the source lumen tubes according to a brachytherapy treatment plan. The device includes an inner tube, and a plurality of source lumen tubes located around the inner tube and including distal ends secured together with the inner tube at the distal end disposed within the body cavity, the source lumen tubes comprising proximal portions sufficiently long to extend outside the breast.