A catheter (12) for the positioning of a radioactive material (24) for therapeutic radiation treatment of the body is disclosed. The catheter includes a radioactive source (24) positioned at the distal end thereof and is sufficiently flexible and strong to navigate in the body to the desired treatment location. The radioactive source may be provided to the catheter in an number of different ways. In one set of embodiments, the radioactive source is bonded to the inner or outer surface of the catheter body (46), a catheter attachment (10) or a carrier positionable within the body.