Based On Finite Element Analysis Of Ultrasound Elastography In Breast Disease

In recent decades, ultrasonic is widely applied in biology, medicine field. The biological tissue's Ultrasound properties are one of the most basic research in the field of medical ultrasound. Both the diagnosis and treatment with biological tissue is closely related to the Ultrasound properties in the application of ultrasound in medicalMedical ultrasound is the combination subject of ultrasonics and medicine science. Its main task is to study the ultrasonic's propagation, regularity and application in biological tissue. The ultrasound may be scattering, absorption and refraction when the ultrasound in an organization. These changes can offer us some information about the organization.Ultrasound elastography often use static/quasi-static incentive method. This method uses a probe or a probe-extrusion plate device compressing the organization along thevertical(axial), imposing a small strain to the tissue (such as 1% of magnitude), then collecting theultrasound signals(RF signals) or the envelope signals before and after compressing the tissueseparately, using the cross-correlation method to analysis these signals, to estimate the displacement distribution at different positions of the tissue, and get the tissue's strain distribution. If the elastic coefficient is larger, relatively the strain will be smaller. Conversely, the elastic coefficient is smaller, relatively the corresponding strain will be larger. So we know whether the organization diseased through the measurement of elastic imaging.In this thesis, we take organization density of 1.5kg/L, poisson ratio of 0.495, organization boundary conditions of the edge take displacement underneath take on free boundary condition, used Matlab simulation analysis of strain diagram obtained and found that both benign tumor model or malignant tumor model, with normal tissue lesions and elastic contrast (>1) increases, the difference of the strain graph is bigger also, more easily separate lesions, namely ultrasound elastography technology is more suitable for testing elastic large quantities of foreign bodies, and for an elastic contrast of heterogeneities less than 1 case, is not easy to find to organize the internal foreign bodies distribution.Hospital diagnosis of breast disease results shown that some mammary gland disease and fiber adenoma such as calcification or collagenzation, and mucious adenocarcinoma, elastography will be misdiagnosis.For this kind of circumstance, the simulation test often take benign lesions and malignant lesions, the elastic contrast to compare elastography same of strain figure differences, can find that when has the same round and star mass than the elastic modulus, its X direction and no obvious differences of strain, but they shear strain is more apparent differences of malignant tumor, and contain the shear strain of mammary gland, containing benign tumors than the shear strain of mammary gland are smaller; Along with the mass and organizational elastic modulus ratio decreases, the difference in reducing that obviously degrees, whether in elastography X direction strain, or the shear strain image, are suitable for testing elastic modulus relatively large mass, and for elastic modulus relatively small bump, has some limitationsUsing the method of finite element analysis and theory of mechanics of elasticity,strain profiles of soft tissue under different circumstance were calculated and presented in this paper. This method plays an important assistant role in theoretical analysis of elastography. Using this method,different condition of soft tissue and effects of mechanical parameters on soft tissue can be studied. Also, limitation of elastography can be estimated theoretically.