Optimal suppression of therapeutic interference for real-time therapy and imaging with an integrated HIFU/imaging transducer

In ultrasound imaging-guided HIFU (High-Intensity Focused Ultrasound) treatment by using an integrated HIFU/imaging transducer, the reflected therapeutic wave significantly interferes with the imaging signal during simultaneous therapy and imaging. In order to obtain ultrasound B-mode images with acceptable resolution, these interferences should be minimized at least to -40 dB level. It was previously demonstrated that coded excitation with fixed notch filtering could reduce the sidelobe level of the HIFU interference to lower than -40 dB while normal short pulse excitation showed higher than a -30 dB sidelobe level due to remnant ripples after fixed notch filtering. In this article, we presented that both HIFU noise and remnant ripples for short pulse excitation could be minimized by using an adaptive HIFU interference suppression technique. A prototype integrated HIFU/imaging transducer with cylindrically shaped aperture was fabricated and A-mode signal and B-mode image experiments were performed to prove the feasibility of the proposed method experimentally.