A.A. Semchenkov, A.N. Kalinichenko

The purpose of the research is to develop a new algorithm for reconstruction of the conductivity of the breast to increase the sensitivity and specificity of the method of electrical impedance tomography. The source data for the development of reconstruction algorithms is the data about distribution of potential on the surface and inside the studied object, depending on the position and properties of the inclusion with higher conductivity (tumor). The computer model was developed to obtain source data. The model is a matrix of 3700 resistors in the form of cylinder. The whole model consists of 5 main layers with intermediate layers of resistors. The upper layer of the cylindrical model, the corresponding layer of the skin of the breast, consist of resistors with nominal value 10 kOhm. 256 nodes of upper layer formed by resistors, each of this nodes can be connected to the positive pole of a current source. Voltages can be calculated in all nodes. The inside layers of the model (from second to fourth) are composed of resistors with nominal value 100 ohms. The tumor is simulated by changing the resistance of 12 resistors, that makes up the cube. The model is created and calculated in program Micro-Cap 9. The distributions of changes in the potentials ∆φ on the upper layer model are shown in the article: ∆φ = φref ? φmeas (1) for each node of upper layer, where φref - reference electrical potential, calculated using the model without inclusion with higher conductivity (without imitation of breast tumor), φmeas - electrical potential, calculated using the model with inclusion with higher conductivity (with imitation of breast tumor). The changes in the sizes of «areas of changes of electrical potential» and values of ∆φ depending of the ratio of conductivities of inclusion and object σrat are shown in the article. σrat = σtum / σobj , (2) where σtum - conductivity of resistors which imitate a tumor, σobj - conductivity of other resistors of inside layers which imitate healthy tissues of a breast. The results of the research of the changes in the sizes of «areas of changes of electric potential» and values of ∆φ depending of the depth of location of inclusion with higher conductivity (analog of tumor) are shown on the figures. The use of such models in practice makes it possible to make preliminary researches on the distribution of poten-tial on the surface and inside the object of study, to simulate the use of various electrode positions without creat-ing physical models and laboratory facilities.