Design and realisation of a microwave three-dimensional imaging system with application to breast-cancer detection

An active microwave-imaging system for non-invasive detection of breast cancer based on dedicated hardware is described. Thirty-two transceiving channels are used to measure the amplitude and phase of the scattered fields in the three-dimensional (3D) imaging domain using electronic scanning. The 3D inverse electromagnetic scattering problem is then solved in order to reconstruct the distribution of the complex permittivity in the imaging domain. The dedicated hardware is based on an array architecture allowing for a short acquisition time while maintaining a high sensitivity, which is important for measurement accuracy and reproducibility as well as for patient comfort. The dedicated hardware achieves a receiver noise figure of 2.3 dB at a gain of 97 dB. The operating frequency range is from 0.3 to 3 GHz. The image acquisition time at one frequency is approximately 50 s and an image is created within 2 h using the single-frequency reconstruction algorithm. The performance of the system is illustrated by an analysis of the standard deviations in amplitude and phase of a series of measurements as well as by a simple image reconstruction example.