An ultrasonic system operable at high drive frequencies and/or in pulsed operation is disclosed. The system may be used in a procedure to treat an occluded blood vessel. The system can be used to transmit ultrasonic energy from an ultrasonic transducer to a distal end of an ultrasonic transmission device. The ultrasonic device may operate at a resonant frequency. The resonant frequency can be determined prior to using the device and/or during use. The ultrasonic device may operate in a range of frequencies at or near resonance. Operational parameters including, for example, reflected vibrations, temperature, and/or user input can be used by the system to adjust the driving waveform.