Ricerc@Sapienza

This paper presents a study on the convergence criteria of a method of moment based software. A mesh convergence study on a simple dipole antenna and a more complex antipodal Vivaldi antenna was performed through WIPL-D environment. The Vivaldi antenna can be used for microwave imaging of liver thermal ablation treatments.

In this communication, we present a full-wave numerical study aimed at showing the potential of microwave tomography as a tool to monitor microwave ablation of solid tumors. The goal is to track the changes in dielectric properties of the tissue undergoing the treatment, in order to appraise the evolving dimension and shape of the thermally ablated area surrounding the applicator.

Forward-looking ground penetrating radar (FL-GPR) is an emerging modality that permits standoff sensing of targets buried at shallow depths in the ground. Most FL-GPR imagery is obtained using free-space approximation, neglecting the presence of the air-to-ground interface and assuming the propagation as occurring in a homogeneous dielectric medium. In this paper, we compare the performance of the approximate free-space tomographic imaging with that of a tomographic algorithm which accounts for the presence of the actual halfspace geometry.

This paper investigates the performance of an advanced imaging procedure for ground penetrating radar (GPR) operating in contactless configuration, i.e., when data are collected at variable distances from the air-soil interface. A data processing procedure is presented, based on an advanced implementation of a microwave tomographic approach. This improved version, recently proposed by the authors, is able of accounting for the near-field distribution generated by a directional transmitting antenna.

We present an image-domain adaptive likelihood ratio tests (LRT) detector for low-signature target detection in forward-looking ground-penetrating radar. We exploit multiview tomographic images of the scene under investigation to iteratively adapt the statistics of the targets and clutter arising from the interface roughness. Using numerical electromagnetic data, it is shown that the proposed adaptive LRT detector provides significantly lower false-alarm rates compared with its nonadaptive counterpart while providing comparable detection performance.

In this contribution, we describe the design and the radiation features of a dual-mode operation low-profile, low-cost, wideband antenna. The structure is made by an annular, 2-D radially periodic, leaky-wave antenna enabling the generation of both high-gain beams in the far-field and of nondiffracting waves within the near-field radiative region. This is obtained through the generation of a fast backward spatial harmonic supported by a metal-strip grating placed on a grounded dielectric slab.

We present an enhanced imaging procedure for suppression of the rough surface clutter arising in forward-looking ground-penetrating radar (FL-GPR) applications. The procedure is based on a matched filtering formulation of microwave tomographic imaging, and employs coherence factor (CF) for clutter suppression. After tomographic reconstruction, the CF is first applied to generate a "coherence map" of the region in front of the FL-GPR system illuminated by the transmitting antennas.

This paper focuses on the use of the Canny edge detector as the first step of an advanced imaging algorithm for automated detection of hyperbolic reflections in ground-penetrating radar (GPR) data. Since the imaging algorithm aims to work in real time; particular attention is paid to its computational efficiency. Various alternative criteria are designed and examined, to fasten the procedure by eliminating unnecessary edge pixels from Canny-processed data, before such data go through the subsequent steps of the detection algorithm.

Thermal ablation treatments are gaining a lot of attention in the clinics thanks to their reduced invasiveness and their capability of treating non-surgical patients. The effectiveness of these treatments and their impact in the hospital's routine would significantly increase if paired with a monitoring technique able to control the evolution of the treated area in real-time. This is particularly relevant in microwave thermal ablation, wherein the capability of treating larger tumors in a shorter time needs proper monitoring.

This communication describes the ongoing efforts towards the assessment of microwave imaging as a tool for real-time monitoring of thermal ablation treatments. In particular, the ex-vivo experimental set-up adopted for the validation is described, and the results of a preliminary experiment are shown. Notably, by analyzing pre- and post-ablation treatment data it is possible to recognize the footprint of the interface between the ablated and not-ablated tissue, making it possible to estimate the boundary of the treated area.