Review of Microwave Near-Field Sensing and Imaging Devices in Medical Applications.

Microwaves can safely and non-destructively illuminate and penetrate dielectric materials, making them an attractive solution for various medical tasks, including detection, diagnosis, classification, and monitoring. Their inherent electromagnetic properties, portability, cost-effectiveness, and the growth in computing capabilities have encouraged the development of numerous microwave sensing and imaging systems in the medical field, with the potential to complement or even replace current gold-standard methods. This review aims to provide a comprehensive update on the latest advances in medical applications of microwaves, particularly focusing on the near-field ones working within the 1-15 GHz frequency range.

Convergence and stability assessment of Newton-Kantorovich reconstruction algorithms for microwave tomography.

For newly developed iterative Newton-Kantorovitch reconstruction techniques, the quality of the final image depends on both experimental and model noise. Experimental noise is inherent to any experimental acquisition scheme, while model noise refers to the accuracy of the numerical model, used in the reconstruction process, to reproduce the experimental setup. This paper provides a systematic assessment of the major sources of experimental and model noise on the quality of the final image.

Quantitative microwave imaging with a 2.45-GHz planar microwave camera.

This paper presents microwave tomographic reconstructions of the complex permittivity of lossy dielectric objects immersed in water from experimental multiview near-field data obtained with a 2.45-GHz planar active microwave camera. An iterative reconstruction algorithm based on the Levenberg-Marquardt method was used to solve the nonlinear matrix equation which results when applying a moment method to the electric field integral representation.

Planar and cylindrical active microwave temperature imaging: numerical simulations.

A comparative study at 2.45 GHz concerning both measurement and reconstruction parameters for planar and cylindrical configurations is presented. For the sake of comparison, a numerical model consisting of two nonconcentric cylinders is considered and reconstructed using both geometries from simulated experimental data.

Microwave imaging of tissue blood content changes.

Active microwave imaging gives information on the dielectric properties of of the body, allowing the collection of data that are distinct from, but complementary to, those available from other imaging methods based on different radiations. Two types of microwave imaging systems have been developed. The first is a planar system that irradiates the object with a plane wave and collects scattered phase and amplitude data at 1024 points on a parallel plane.

Active microwave tomographic imaging of isolated, perfused animal organs.

The relative transparency of biological materials to high-frequency electromagnetic waves has encouraged the development of new systems for imaging. This report describes experiments of microwave tomography conducted on a prototype. The object to be analyzed is submerged in water and is illuminated by a plane wave.

Microwave thermography--characteristics of waveguide applicators and signatures of thermal structures.

In this paper, we study the problem of the interpretation of the signals provided by microwave thermography, which allows the detection of the thermal gradients in living tissues. These signals correspond to the thermal noise measured by a radiometer when the probe scans the surface of the tissues (passive process). We describe how these signals can be computed by means of a new method based on the antenna reciprocity principle.

Electrical characteristics of waveguide applicators for medical applications.

This work concerns the electrical properties of waveguide applicators consisting of flanged rectangular waveguides filled with a dielectric, used in medical applications (microwave thermography and local hyperthermia). The reflection coefficient and the near field configuration in lossy materials were obtained in some cases analytically and in some other cases numerically. The validity of these methods was verified experimentally.