High pressure focused ultrasound field characterization

Abstract

High intensity focused ultrasound (HIFU) transducers are novel and very attractive tools for cancer therapy. They produce very high pressure acoustic fields up to tens of MPa at the focus; thus, acoustic characterization of HIFU fields must be investigated in order to ensure the safe and effective use in clinical applications. A needle hydrophone has been used for HIFU transducer characterization in the newly designed home made system at TÜBİTAK UME (The Scientific and Technological Research Council of Turkey, the National Metrology Institute) Ultrasound laboratory. TÜBİTAK UME HIFU measurement system was controlled by a Labview based data translation program. The driving signal was generated by signal generation card and output from the hydrophone was fed directly into a DSO oscilloscope card. The controlling program executed a “capture-analyze-move” cycle, allowing a large number of measurements to be made. Field scanning measurements are made between 1 MPa, 2 MPa, and 3 MPa pressures. Theoretical model for the beams of periodic waves with an initially uniform amplitude distribution was also performed, based on the Khokhlov-Zabolotskaya-Kuznetsov equation. Numerical solutions were compared with the experimental data and found to be in agreement.