A system for delivering a treatment agent such as a radioactive source 26 to a targeted treatment site within a patient's body is disclosed. Aspects of the device provided herein include a cable 42 with contiguous sections 44 and 46 having different flexibility characteristics made from a same material or material mixture throughout. For example, the material can mixture have first filaments 48 made from a first material and second filaments 50 made from a second material wherein the first material 52 and second material 54 having different annealing temperatures.
