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Inversion layer technique can increase the centre frequency (f0) and the −6 dB bandwidth of the ultrasound transducer without reducing thickness of active material. However, it suffers from the reduced −6 dB bandwidth when the centre frequency is increased more than 1.5f0. A modified inversion technique is proposed and applied it to high‐frequency intravascular ultrasound (IVUS) transducer. The performance was computationally verified by using finite element method (FEM) simulation. The proposed IVUS transducer consists of two sub‐elements with each aperture size of 0.6 × 0.6 mm, and each sub‐element has different types of inversion layer using PMN‐PT and PZT‐5H. The initial thickness of overall active material was designed for 40 MHz centre frequency and the FEM simulation showed that the centre frequency was increased by about 1.8f0 maintaining the −6 dB fractional bandwidth compared with the conventional transducer. [ABSTRACT FROM AUTHOR]

Real‐time ultrasound imaging during high‐intensity focused ultrasound (HIFU) surgery allows for tracking tissue movement and monitoring feedback from a treated target. However, the reflected HIFU interference signals deteriorate the quality of imaging signals received by an imaging transducer during simultaneous therapy and imaging. The purpose of this Letter is to demonstrate that those HIFU interference signals can be significantly reduced in the brightness‐mode image by using a coded excitation scheme with adaptive notch filtering. A prototype integrated HIFU/imaging transducer was used to experimentally demonstrate the performance of the proposed method. [ABSTRACT FROM AUTHOR]