A system for treating a bifurcated vessel comprises a first delivery catheter and a second delivery catheter. The hollow interior of the tube extends into the tip with the same diameter as in the tube, but the wall thickness of the tip is reduced from that of the tube. The CAD navigation function uses coordinates for converting an image-shift moving amount to a DUT stage moving amount in communications between an image processing unit for processing charged particle beam images and a memory for storing information on circuit line patterns.