A flexible, multi-lumen brachytherapy device includes a plurality of loose lumens extend through a hub towards a single point of attachment at a distal rigid section. Because the lumens are attached at only a single distal location, the lumens are free to move axially and rotatably, thereby increasing the overall flexibility of the device to thereby decrease intermittent device movement while increasing patient comfort. A novel keyed stylet can be selectively inserted to increase the rigidity of the device as needed. The ability to dynamically modify the rigidity of the brachytherapy device provides a comprehensive brachytherapy solution that satisfies concerns of the patient, the surgeon and the radiologists.