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.

Microwave thermal ablation treatments induce coagulation necrosis of diseased tissue through the absorption of an electromagnetic field at microwave frequencies. In particular, the electromagnetic field absorbed by the tissue induces a temperature increase that, in turn, produces an almost instantaneous cell death. The electromagnetic field is radiated by a minimally invasive antenna located in the centre of the diseased area.

Low-cost and reliable methods for monitoring the size of the ablation zone during microwave thermal ablation (MTA) are crucial in the oncological clinical practice. The aim of this work is to test the performance of electrical impedance tomography (EIT) for the real-time monitoring of the ablation area where relevant temperature increases occur. In this work, two experimental studies were performed with a 16-electrode EIT system using a liver-mimicking agar phantom. First, an EIT system was tested to monitor the cooling of the phantom from an initial temperature of about 72°C.

Microwave thermal ablation (MTA) therapy for cancer treatments relies on the absorption of electromag- netic energy at microwave frequencies to induce a very high and localized temperature increase, which causes an irreversible thermal damage in the target zone. Treatment planning in MTA is based on exper- imental observations of ablation zones in ex vivo tissue, while predicting the treatment outcomes could be greatly improved by reliable numerical models.

Treatment planning in microwave thermal ablation (MTA) requires the capability to predict and estimate the shape and dimension of the thermally coagulated zone obtainable following a clinical protocol. The ultimate result relies on the knowledge of the performance of the ablation device, as well as of the temperature-dependent structural modifications that the tissue undergoes during the treatment, because of the very high temperatures reached (up to 100 °C or higher).

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.

Purpose: To evaluate, characterise and compare the extent of tissue shrinkage induced from three different commercial microwave ablation devices, and to elucidate the mechanism behind the distinctive performances obtained. Materials and methods: Microwave ablation (N = 152) was conducted with three different commercial devices on cubes of ex vivo liver (10–40 ± 2 mm/side) embedded in agar phantoms. 50–60 W was applied for 1–10 min duration. Pre- and post-ablation dimensions of the samples, as well as the extent of carbonisation and coagulation were measured and correlated.

Microwave Thermal Ablation (MTA) procedures for the treatment of solid tumours are spreading due to several advantages of the technique with respect to traditional approaches. The success of MTA treatments, combined with their low invasiveness and fast recovery times, allow developing the technique for different and new clinical indications. This contribution describes two possible new scenarios where MTA procedures could be applied, describing the engineering challenges to be considered and solved.

Tissue-equivalent dielectric simulators (also named phantoms) are increasingly used to test electromagnetic systems used close to the human body for compliance or research and development purposes. In compliance applications, phantoms are used to verify electromagnetic field absorption in human tissues with reference to safety guidelines. In research and development applications, phantoms are used for verification and optimization of electromagnetic systems performances during the design phase or to validate, e.g., antenna's performances against specifications in reference conditions.

This study aims at investigating in real-time the structural and dynamical changes occurring in an ex vivo tissue during a microwave thermal ablation (MTA) procedure. The experimental set-up was based on ex vivo liver tissue inserted in a dedicated box, in which 3 fibre-optic (FO) temperature probes were introduced to measure the temperature increase over time. Computed tomography (CT) imaging technique was exploited to experimentally study in real-time the Hounsfield Units (HU) modification occurring during MTA.