Focused ultrasound for medical applications

High-intensity focused ultrasound (HIFU) can be used for the ablation of tissue, such as in the case of prostate cancer. However, targeting tissue deeper inside the body remains challenging due to the increased attenuation and scattering of the ultrasonic waves. In this work, the partial and complete obstruction of the ultrasonic beam from a HIFU transducer at bones was investigated. Ultrasonic transmission and reflection under such conditions have scarcely been the focus of previous research. Thus, this work provided a reference based on numerical and experimental results. To this end, numerical simulations were conducted for various bone obstruction configurations as well as a new experimental setup was developed in which focused ultrasonic waves were generated, and temperature and pressure fields at the target area were recorded. In addition, a diffraction-based shadowgraph technique was used for the ultrasound visualization in laboratory experiments. Furthermore, new analysis techniques were developed to process shadowgraph images and to extract quantitative information. Overall, the results of this work provides a basis for future research in the field of therapeutic ultrasound.

IACUC Number: 1819-008a