Microwave tomography: two-dimensional system for biological imaging

Abstract

Microwave tomographic imaging is one of the new technologies which has the potential for important applications in medicine. Microwave tomographically reconstructed images may potentially provide information about the physiological state of tissue as well as the anatomical structure of an organ. A two-dimensional (2-D) prototype of a quasi real-time microwave tomographic system was constructed. It was utilized to reconstruct images of physiologically active biological tissues such as an explanted canine perfused heart. The tomographic system consisted of 64 special antennae, divided into 32 emitters and 32 receivers which were electronically scanned. The cylindrical microwave chamber had an internal diameter of 360 mm and was filled with various solutions, including deionized water. The system operated on a frequency of 2.45 GHz. The polarization of the incident electromagnetic field was linear in the vertical direction. Total acquisition time was less than 500 ms. Both accurate and approximation methods of image reconstruction were used. Images of 2-D phantoms, canine hearts, and beating canine hearts have been achieved. In the worst-case situation when the 2-D diffraction model was used for an attempt to "slice" three-dimensional (3-D) object reconstruction, we still achieved spatial resolution of 1 to 2 cm and contrast resolution of 5%.

3d Sliced Tomographic Inverse Scattering Experimental Results

“…It is well known that, as diffraction and scattering phenomena at microwave frequencies are relevant, the sliced approach does not permit to obtain quantitative reconstructions [10,11]. However, it has been also shown, by numerical examples, that it allows to localize and to roughly retrieve the silhouette of elongated scatterers [12].…”

High Resolution Biological Visualization Techniques

“…The electronic tissue details can provide histological and pathological information non-invasively and in-vivo. The mechanism of action relies on the cellular components' dielectric properties that will influence the wave propagation and hence act as a sensing mechanism (Semenov et al, 1995, Semenov et al, 1996. Spectroscopic imaging for all wavelength ranges uses the alteration in the spectral structure of the input signal both in the time and frequency domain as a result of interaction with the biological medium.…”

Breast Cancer Detection Using a Hybrid Finite Difference Frequency Domain and Particle Swarm Optimization Techniques

“…Also, microwave imaging is a non-ionizing method which probably will be rather inexpensive compared to MRI and safer compared to X-ray. Versions of video pulse radars were first introduced for medical applications as a means to detect malignancy in internal biological tissues by Hagness et al [8][9][10]. Fear et al [11][12][13] demonstrated the feasibility of detecting and localizing small tumors in three dimensions.…”