High voltage staircase drive circuit for triggered high-intensity focused ultrasound treatment

In triggered high-intensity focused ultrasound (HIFU) treatment, cavitation clouds are produced by extremely high intensity trigger pulses and enhance the effect of following heating waves. The ultrasound intensity must be quickly changed from that for trigger pulses to that for heating waves before cavitation clouds vanish. We newly designed and constructed a class D amplifier based on a staircase voltage drive concept, which has the capability of outputting high voltage waves for trigger pulses and continuous waves for heating waves and the capability of fast switching between the two modes. Its efficacy was confirmed by an experiment with a BSA containing polyacrylamide gel.