Imaging of high-intensity focused ultrasound-induced lesions in soft biological tissue using thermoacoustic tomography

Abstract

A robust needle hydrophone has been developed for HIFU transducer characterization and reported on earlier [1]. After a brief review of the hydrophone design and performance, we demonstrate its use to characterize a 1.5 MHz, 10 cm diameter, F-number 1.5 spherically focused source driven to exceed an intensity of 1400 W/cm at its focus. Quantitative characterization of this source at high powers is assisted by deconvolving the hydrophone`s calibrated frequency response in order to accurately reflect the contribution of harmonics generated by nonlinear propagation in the water testing environment. Results are compared to measurements with a membrane hydrophone at 0.3% duty cycle and to theoretical calculations, using measurements of the field at the source`s radiating surface as input to a numerical solution of the KZK equation.

Key Words: Hydrophone, HIFU, cavitation, KZK
PACS: 43.35.Yb