Modeling pressure distribution and heat in the body tissue and extract the relationship between them in order to improve treatment planning in HIFU

Abstract

In high intensity focused ultrasound (HIFU) systems using non-ionizing methods in cancer treatment, if the device is applied to the body externally, the HIFU beam can damage nearby healthy tissues and burn skin due to lack of knowledge about the viscoelastic properties of patient tissue and failure to consider the physical properties of tissue in treatment planning. Addressing this problem by using various methods, such as MRI or ultrasound, elastography can effectively measure visco-elastic properties of tissue and fits within the pattern of stimulation and total treatment planning. In this paper, in a linear path of HIFU propagation, and by considering the smallest part of the path, including voxel with three mechanical elements of mass, spring and damper, which represents the properties of viscoelasticity of tissue, by creating waves of HIFU in the wire environment of MATLAB mechanics and stimulating these elements, pressure and heat transfer due to stimulation in the hypothetical voxel was obtained. Through the repeatability of these three-dimensional elements, tissue is created. The measurement was performed on three layers. The values of these elements for liver tissue and kidney of sheep in a practical example and outside the body are measured, and pressure and heat for three layers of liver and kidney tissue of an organism were obtained by applying ultrasound signals with a designed model. This action is repeated in three different directions, and the results are then compared with simulation software for ultrasound, as a reference to U.S. Food and Drug Administration (FDA) measures for HIFU, as well as comparisons of results with an operational method for an HIFU cell.