The reconstruction of internal structures and the detection of inhomogeneities are crucial in modern non-destructive testing and medicine. This process aims to identify regions with distinct electrical properties, such as variations in dielectric function, within an object situated in free space. Such anomalies, like tumors or hidden objects, exhibit significantly different parameters from their surroundings. In medicine, early disease diagnosis necessitates the use of low-frequency ranges for patient safety. Microwave tomography, utilizing electromagnetic waves from 0.5–10 GHz, is a promising technique for assessing tissue dielectric properties. Tumor tissues, characterized by higher water and ion content, typically possess dielectric values and conductivity 2–5 times greater than healthy tissues. This enhanced dispersion and absorption of microwave radiation by malignant tumors facilitates their effective detection. Consequently, algorithms capable of efficiently analyzing and reconstructing internal body structures from near-field electromagnetic data are highly sought after in science and technology. In this paper, the initial diffraction problem is rewritten as an integral equation and solved using a two-step method. The main advantage of this method is the reduction of a nonlinear problem to a linear one and the use of a recalculation formula. This allows us to avoid using iterative methods. The problem under consideration is very computationally complicate, so parallel computing methods are used to solve it.