The invention relates to a radiopaque catheter tip and catheter assembly having radiopaque elements associated with a catheter. The surface electrode of a vertical-type bipolar transistor in which a P-type epitaxial growth layer and a P-type semiconductor substrate form the collector is electrically connected to the drain electrode of a lateral MOSFET by means of a metal electrode wiring. In addition, an actuator controls a displacement of the guiding roller according to a feedback signal generated by the sensor.