Interaction of high intensity focused ultrasound with biological material
Abstract:
This work is motivated by the possible medical application of focused ultrasound in minimally invasive treatment of a variety of disorders including those associated with soft tissue or disk element disruption in the vicinity of the spine causing impingement on the spinal cord. The hypothesis is that thermal spikes induced by focused ultrasound will cause the tissues to shrink and thus restore stability to the spine and/or reverse the weakness in the structural element. A prototype setup consisting of a transducer in the shape of a spherical cap was used to conduct tests on biological materials. Our
preliminary results indicate that the heating efficiency of the ultrasound energy in the focal region depends on the exciting frequency and the geometry of the focal zone depends on the material being tested. We have investigated the influence of the exciting frequency, system geometry and the specimen’s material properties on the nature of lowenergy focused ultrasonic wavefield using a finite element based program called Pzflex. The preliminary results of our laboratory experiments and the numerical simulations are presented in this paper. At higher excitation energies, cavitation and nonlinear effects need to be included in the simulations. These effects are under current investigation.
Keywords: focused ultrasound, HFU, PZFlex.