Liver cancer is one of the leading causes of death in the world. High intensity focused ultrasound (HIFU) is a rapidly developing medical technology for conducting non-invasive tumor ablation therapy in various organs of the body. One of the major objectives of this study is to achieve a virtually complete necrosis of tumors close to major blood vessels and to avoid blood vessel damage. The three-dimensional (3D) acoustic-thermal-hydrodynamic coupling model is proposed to compute the pressure, temperature, and blood flow velocity in the patient specific geometry. At high frequencies propagation of ultrasound in the medium is a non-equilibrium process and relaxation effects should be taken into account. The nonlinear Westervelt equation with relaxation effects and bioheat equations in both the hepatic parenchyma and blood vessels are considered. The classical nonlinear Navier-Stokes equations related to mass and momentum conservations in large hepatic blood vessels are employed both for convective cooling and acoustic streaming. From this three-dimensional study it is found that relaxation effects can significantly affect the amount of ultrasound energy deposited to the tumor. In large blood vessels both convective cooling and acoustic streaming can change the temperature considerably near blood vessels.
Date:
2015-07
Relation:
Proceedings of the 22nd International Congress on Sound and Vibration. 2015 Jul:Abstract number 121474.
