Medical appliance with centering balloon

This invention relates to a medical appliance for the treatment of a portion of body vessel by ionizing radiation, comprising a catheter, an inflatable elongated balloon distally surrounding the catheter, and lumen means longitudinally extending through the catheter for positioning a radioactive radiation emitter within the balloon. The balloon catheter comprises a catheter tube surrounded distally by an elongated inflatable balloon. Throughout the catheter tube is a longitudinal lumen for positioning a radioactive radiation emitter within the balloon. The catheter comprises a second lumen for directing inflation fluid into the balloon. Belt means creating a waist are mounted on the balloon to squeeze it down to nearly the diameter of the catheter thereby leaving a small passage for the inflation fluid. The belt means divide the balloon into sections to assure a close center fit of the catheter within the balloon.