A balloon catheter is provided that may be used to dilate hardened regions of a stenosis. Viewed in the flow direction, it is provided that the clear cross-section of the hollow block in the outflow region reduces uniformly in the direction toward the outflow and the end face of the bottom of the hollow block is designed with respect to the surface of the continuous belt such that the melt contacts the continuous belt perpendicularly. First, threads are attached to the anchor. The transparent antenna rod is fixed on the main body.