Beamforming Antenna Arrays and Metasurfaces for Medical Imaging: From Overview to Suggesting a new Imaging Modality

This paper presents a detailed overview of new medical imaging methods for early-stage breast cancer detection and discusses their pros and cons. Then, it introduces a new Microwave Imaging (MWI) modality using near-fields and evanescent waves. Three factors control the penetration depth and the spatial resolution of the proposed imaging method. Indeed, these factors introduce a new degree of freedom to control and enhance imaging systems, meaning spatial resolution and image contrast. In fact, the selection of the operating frequency band is one of the most challenging problems for the proposed modality to reconstruct and obtain medical images from a breast with proper image contrast and resolution. Simulation results prove that images with proper contrast and imaging system resolution can be achieved using higher operation frequencies. However, it appears that deeper locations can be imaged using higher frequencies in the proposed method just by selecting suitable values for the other controlling parameters. Moreover, the phase gradient rate over the antenna array or metasurface can control the penetration depth of the imaging system. Undoubtedly, increasing phase gradient rate decreases imaging depth. The third parameter which controls imaging with a periodic array of sensor antennas is the integer index of the excited spatial harmonic. By increasing the index range from 0 to infinity, the penetration depth of the imaging system decreases. Finally, it is evident that to acquire a proper medical image using the offered method a trade-off should be applied between these three parameters.