the disclosure describes a device for asymmetrical irradiation of a body cavity or site , such as after removal of tissue , e . g . biopsy or lumpectomy . the device includes an elongated tubular shaft having an inner lumen and a tubular wall with a plurality of lumens extending within the wall which are configured for receiving a radiation source . the distal portion of the tubular shaft is cut into a plurality of longitudinally separated wall segments with a lumen extending within at least one of the wall segments . a support member is positioned within the separated wall segments to support and position the wall segments in a desired configuration for brachytherapy . an expandable member such as an inflatable balloon is mounted on the distal shaft portion about the separated wall segments wall which when inflated secures the distal shaft portion within a desired intracorporeal site for brachytherapy treatment .