Forward modeling of propagation and scattering of acoustic waves for hyperthermia treatment

Abstract

Cancer is a major cause of death in the Western world, resulting in a high demand for effective therapies. Recently, there is increasing interest in treatment via high intensity focused ultrasound (HIFU) where ultrasonic waves are used to increase the tumor temperature to induce cell death. For successful treatment, information about the temperature is essential. Research is applied where temperature profiles are obtained via acoustic wavefields. In order to understand the measurements and to verify imaging methods the acoustic wavefields are modeled. The forward model is based on a nonlinear integral equation of the second kind, obtained via reciprocity from the acoustic wavefield equations. The integral equation relates the unknown total wavefields with the known incident wavefields and inhomogeneities in density and compressibility. A conjugate gradient method is used to solve the integral equation to obtain a solution for this ill-posed problem. To reduce the computational costs, a technique called ‘‘marching on in anything’’ is applied in both the temporal and the spatial domain. This technique is especially successful where wavefields have to be computed for various transducer positions. Results will be shown where the propagation and scattering of acoustic waves are modeled by using the above method.