46 documents found, page 1 of 5
Best Practices for Accurate Results Using Numerical Solvers for Microwave Body ...
Martins, Raquel A.; Godinho, Daniela M.; Felício, João M.; Savazzi, Matteo; Costa, Jorge R.; Conceição, Raquel C.; Fernandes, Carlos A.In this paper, we indicate best practices that should be observed when using numerical solvers for microwave body sensing. We show the impact of not minding these aspects in the case of microwave breast scanning, using the Computer Simulation Technology software tool. To this end we simulate a homogeneous breast with a 5-mm radius spherical tumor placed inside. The breast is illuminated by a broadband antenna t...
Validation of Dielectric Properties Estimation from Magnetic Resonance Images t...
Godinho, Daniela M.; Castela, Tiago; Felício, João M.; Silva, Nuno A.; Orvalho, M. Lurdes; Fernandes, Carlos A.; Conceição, Raquel C.Knowledge about dielectric properties of biological tissues is critical for the development and validation of microwave systems, such as Microwave Imaging (MWI) prototypes. However, measurement of dielectric properties of heterogeneous tissues with conventional techniques present some challenges, as most adopted techniques are designed for homogeneous tissues, and limited number of samples may be available. In ...
Experimental Assessment of Axillary Lymph Node Microwave Tomography Using Anthr...
Savazzi, Matteo; Karadima, Olympia; Duarte, David O. Rodriguez; Tobon, Jorge; Vipiana, Francesca; Kosmas, Panagiotis; Fernandes, Carlos A.Abstract—We assess the application of microwave tomography (MWT) for the detection of axillary lymph nodes (ALNs) in breast cancer patients. We numerically study the effects of limiting angular view in axillary MWT, as probes can only be placed on a limited arc around the axillary region. We also numerically study the possibility of increasing the amount of retrievable information by acquiring data in two conse...
A feasibility study on real-time concealed object detection in foliage using ST...
Duarte, Luís; Vala, Mário; Ribeiro, Carlos; Alves, Luis N.; Fernandes, Carlos A.; Caldeirinha, Rafael F. S.This paper reports on the first results of a Swept Time-Delay Cross Correlator (STDCC) based radar performance for the detection of concealed objects in a foliage. The real-time STDCC radar operating at 25 GHz with 500 MHz bandwidth detection capabilities is benchmarked together with a VNA technique using a central frequency of 11 GHz with 18 GHz bandwidth. A set of measurements were performed to assess the att...
Experimental Evaluation of an Axillary Microwave Imaging System to Aid Breast C...
Godinho, Daniela M.; Felicio, Joao M.; Fernandes, Carlos A.; Conceicao, Raquel C.The number of metastasised Axillary Lymph Nodes (ALNs) is a key indicator for breast cancer staging. Its correct assessment affects subsequent therapeutic decisions. Common ALN screening modalities lack high enough sensitivity and specificity. Level I ALNs produce detectable backscattering of microwaves, opening the way for Microwave Imaging (MWI) as a complementary screening modality. Radar-based MWI is a low-...
Target Selection in Multistatic Microwave Breast Imaging Setup Using Dielectric...
Godinho, Daniela M.; Felicio, Joao M.; Fernandes, Carlos A.; Conceicao, Raquel C.Microwave Imaging (MWI) has been studied to aid early breast cancer detection. Current prototypes in more advanced stages of development include both monostatic or multistatic setups. However, multistatic configurations usually include a high number of antennas which consequently require complex and computationally-intensive signal processing algorithms to ensure a good target detection. We previously presented...
Effect of Varying Prior Information in Axillary 2D Microwave Tomography
Savazzi, Matteo; Karadima, Olympia; Felicio, Joao M.; Fernandes, Carlos A.; Kosmas, Panagiotis; Conceicao, Raquel C.We numerically assess the potential of microwave tomography (MWT) for the detection and dielectric properties estimation of axillary lymph nodes (ALNs), and we study the robustness of our system using prior information with varying levels of accuracy. We adopt a 2-dimensional MWT system with 8 antennas (0.5-2.5 GHz) placed around the axillary region. The reconstruction algorithm implements the distorted Born it...
Evaluation of Refraction Effects in Dry Medical Microwave Imaging Setups
Godinho, Daniela M.; Felicio, Joao M.; Fernandes, Carlos A.; Conceicao, Raquel C.Dry microwave imaging (MWI) systems are more practical, hygienic, and fast to operate since they do not require immersion liquid. However, the dielectric contrast between air and the part of the body under examination is larger, causing larger refraction effects. Including refraction in the image reconstruction algorithm significantly increases the computational effort, especially when imaging nonuniform shapes...
Development of MRI‐based axillary numerical models and estimation of axillary l...
Godinho, Daniela M.; Felício, João M.; Castela, Tiago; Silva, Nuno A.; Orvalho, Maria de Lurdes; Fernandes, Carlos A.; Conceição, Raquel C.Purpose: Microwave imaging (MWI) has been studied as a complementary imaging modality to improve sensitivity and specificity of diagnosis of axillary lymph nodes (ALNs), which can be metastasized by breast cancer. The feasibility of such a system is based on the dielectric contrast between healthy and metastasized ALNs. However, reliable information such as anatomically realistic numerical models and matching d...
Study of Freezing and Defrosting Effects on Complex Permittivity of Biological ...
Savazzi, Matteo; Felicio, Joao M.; Costa, Jorge R.; Fernandes, Carlos A.; Conceicao, Raquel C.In this letter we study the effect of freezing and defrosting on the dielectric properties of biological tissues. The electromagnetic characterization of tissues at microwave frequencies is crucial for the development of microwave-based biomedical devices. These measurements are often not practical, as tissue degradation restricts the time available between tissue excision and dielectric measurements. For this ...