Design and fabrication of a wide-aperture HIFU annular array transducer for the treatment of deep-seated tumors

In HIFU treatment applications, the annular array transducer is a feasible solution for the clinical/engineering requirements which are as follows: ablation of tumors deep inside body, electronic dynamic focusing in the depth direction, simple configuration/operation, and lower cost due to fewer elements/channels of amplifier. A 12 cm‐diameter, 12 cm‐radius‐of‐curvature annular array transducer has been developed in this study. The pseudo‐inverse method was adopted to calculate the desired phase of each element for focusing, and the Rayleigh‐Summerfield integral was used to obtain the ultrasonic pressure field. In the simulation, the operating frequency was 0.9 MHz, and the acoustic medium was water. A piece of 1–3 piezocomposite was fabricated using the dice and fill technique for the pilot test. The dimension of the sample was 4×2 cm, and it was thermally shaped using a spherical mold of 12 cm in radius. The results of the simulation showed that the focus could not be moved electronically in the depth d...