Nikolai Simonov

3D Microwave Breast Imaging Based on Multistatic Radar Concept System

Microwave imaging (MI) is one of the most promising and attractive new techniques for earlier breast-cancer detection. The microwave tomography (MT) realizes configuration of multistatic multiilumination system and reconstructs dielectric properties of the breast by solving a nonlinear inversion scattering problem. We describe below ETRI 3D MT system and 3D MI reconstruction program. Here we demonstrate also examples of image reconstruction using our MT system.

A fast electromagnetic solver for microwave medical imaging

This paper describes a fast electromagnetic solver that allows to accelerate significantly the microwave imaging program, which produce reconstruction of permittivity and conductivity distribution of the breast under examination for purpose of early concern detection. The reconstruction algorithm is based on the solution of inverse electromagnetic scattering problem using iteration method, which applies to solve a number of relative forward electromagnetic problems. The presented fast solver is developed for a precision microwave tomography that contain the circular array of probe antennas and operates in 3-6 GHz frequency band.

Modeling of a probe antenna for 3D microwave tomography

Simplified model of a probe antenna is regarded for application in the image reconstruction algorithm of the microwave tomography (MT) system operating in 3 to 6 GHz frequency band. This probe model can reduce the computer resources and so as to accelerate the reconstruction algorithm.

Investigation of Phase Singularity Problem in Microwave Breast Tomography

This paper investigates the phase singularity problem in microwave image reconstruction utilizing unwrapped phase data. The measured phases of the electric fields in most microwave measurement systems are wrapped. Thus, a certain phase unwrapping process is necessary for reconstruction of the image of a high contrast object. This unwrapping, however, is difficult in the presence of scattering nulls on/near the unwrapping path. At the null point, the phase value will be rendered, resulting in a poor image reconstruction. In this paper, we investigate the phase singularity arising from electromagnetic scattering nulls in microwave breast tomographic imaging. We then propose a transformation technique for the measured electric fields that avoids phase singularity.

Acceleration of electromagnetic solver for microwave tomography

This paper describes some methods of acceleration of the fast electromagnetic solver for the microwave imaging algorithm. This program is a part of a microwave tomography system, developed as a preclinical prototype for the early cancer detection, and operating in 3 - 6 GHz frequency band. The peculiarity of our algorithm is that it simulates all nearby objects of the breast under test, including probe antenna array, bath liquid-air interface, covering metal screen sheet and human body, but it exploits simplified models for all of them. Such models are based on supporting data of the electromagnetic field distribution, calculated using CST solver.

Investigation of spatial resolution in a microwave tomography system

In this work, we investigated dependence of the spatial resolution in a microwave tomography system on significant parameters such as an operating frequency, dielectric properties of testing material, number of testing antennas, diameter of the circular array, and total amount of measured data. The spatial resolution was calculated in 3 to 6 GHz, based on original estimation method in microwave imaging.

Advanced Fast 3-D Electromagnetic Solver for Microwave Tomography Imaging

This paper describes a fast-forward electromagnetic solver (FFS) for the image reconstruction algorithm of our microwave tomography system. Our apparatus is a preclinical prototype of a biomedical imaging system, designed for the purpose of early breast cancer detection. It operates in the 3–6-GHz frequency band using a circular array of probe antennas immersed in a matching liquid; it produces image reconstructions of the permittivity and conductivity profiles of the breast under examination. Our reconstruction algorithm solves the electromagnetic (EM) inverse problem and takes into account the real EM properties of the probe antenna array as well as the influence of the patient’s body and that of the upper metal screen sheet. This FFS algorithm is much faster than conventional EM simulation solvers. In comparison, in the same PC, the CST solver takes ~45 min, while the FFS takes ~1 s of effective simulation time for the same EM model of a numerical breast phantom.