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On the development of an innovative mm-wave imaging system for breast cancer detection
Full text linkIn this Thesis, a complete study of an innovative mm-wave imaging system for breast cancer detection is presented.
This work is strongly multidisciplinary and involves several partners both inside and outside the University of Pavia. The main medical partner outside the University is the European Institute of Oncology (Italian acronym, IEO), in Milan. Outside the University of Pavia there are also the Institute dElectronique and Telecomunication de Rennes and the University of Malta; while, inside the University there are the bioengineering laboratory, the civil and architecture department, and the laboratory of bioinformatics mathematical modelling and synthetic biology.
In addition, this project was originally funded by the Italian Association for Cancer Research (Italian acronym, AIRC), and it is currently funded by the University of Pavia funding, Blue Sky Research project MULTIWAVE.
This work can be divided in three main branches: the dielectric characterization of biological tissues up to 50 GHz (in particular, human breast ex-vivo samples); the realization of realistic breast phantoms for the test of the prototype on phantoms in a controlled environment; and the test of the mm-wave imaging prototype on realistic breast phantoms.
In particular, in the first chapter of the Thesis, three experimental campaigns both on animal and human tissues (ex-vivo, in-vivo and in-loco) in the frequency range [0.5-50] GHz have been deeply investigated, as the dielectric properties describe the way in which the electromagnetic fields interact with, and propagate within, a tissue, and therefore the exact knowledge of these properties is the starting point for all possible microwave-based technologies.
In the second chapter, several recipes for the preparation of realistic breast phantoms capable of mimicking the dielectric properties of ex-vivo breast tissues up to 50 GHz have been proposed. In particular, two macro-categories of phantom are presented: one based on the use of gelatin as a solidifying agent and on dishwashing liquid as a surfactant to mimic the average dielectric properties of the different categories of healthy and neoplastic breast tissues, and one on the use of waste-oil hardener as a solidifying agent and Polysorbate80 as a surfactant to mimic the dielectric properties of particularly fatty healthy tissues. The dielectric properties of the produced phantoms were compared to the ones of the human breast ex-vivo tissue up to 50 GHz.
In the third and last chapter, the test of the linear prototype of the millimeter wave system for the detection of different types of targets was presented. In particular, two targets in air, metal sphere and cylinder of water and gelatin, and on two targets (cylinder of water and gelatin, and currant) included in two different phantoms (oil and waste-oil hardener, and Polysorbate80 and waste-oil hardener), deep up to 2 cm below the surface of the phantom were used to test the mm-wave imaging prototype. The synthetic array was composed of 24 antennas in 28 positions, with spacing between phase centers of adjacent radiators equal to half wavelength in air at 30 GHz, 5mm. The results showed that the proposed system is able to correctly identify the position of the target in both scenarios, in air and in phantom, with sub-cm resolutions in both cases. Then, in this year, the proof of concept of the feasibility of the imaging system with central working frequency of around 30 GHz for the early detection of breast cancer was demonstrated.
Therefore, in conclusion, in this Ph.D. Thesis, the feasibility of a system of this type for applications of screening and possibly diagnosis for breast cancer in women whose breasts lend themselves to scanning with mammography is demonstrated in many respects, strongly encouraging further analysis in this direction.In this Thesis, a complete study of an innovative mm-wave imaging system for breast cancer detection is presented.
This work is strongly multidisciplinary and involves several partners both inside and outside the University of Pavia. The main medical partner outside the University is the European Institute of Oncology (Italian acronym, IEO), in Milan. Outside the University of Pavia there are also the Institute dElectronique and Telecomunication de Rennes and the University of Malta; while, inside the University there are the bioengineering laboratory, the civil and architecture department, and the laboratory of bioinformatics mathematical modelling and synthetic biology.
In addition, this project was originally funded by the Italian Association for Cancer Research (Italian acronym, AIRC), and it is currently funded by the University of Pavia funding, Blue Sky Research project MULTIWAVE.
This work can be divided in three main branches: the dielectric characterization of biological tissues up to 50 GHz (in particular, human breast ex-vivo samples); the realization of realistic breast phantoms for the test of the prototype on phantoms in a controlled environment; and the test of the mm-wave imaging prototype on realistic breast phantoms.
In particular, in the first chapter of the Thesis, three experimental campaigns both on animal and human tissues (ex-vivo, in-vivo and in-loco) in the frequency range [0.5-50] GHz have been deeply investigated, as the dielectric properties describe the way in which the electromagnetic fields interact with, and propagate within, a tissue, and therefore the exact knowledge of these properties is the starting point for all possible microwave-based technologies.
In the second chapter, several recipes for the preparation of realistic breast phantoms capable of mimicking the dielectric properties of ex-vivo breast tissues up to 50 GHz have been proposed. In particular, two macro-categories of phantom are presented: one based on the use of gelatin as a solidifying agent and on dishwashing liquid as a surfactant to mimic the average dielectric properties of the different categories of healthy and neoplastic breast tissues, and one on the use of waste-oil hardener as a solidifying agent and Polysorbate80 as a surfactant to mimic the dielectric properties of particularly fatty healthy tissues. The dielectric properties of the produced phantoms were compared to the ones of the human breast ex-vivo tissue up to 50 GHz.
In the third and last chapter, the test of the linear prototype of the millimeter wave system for the detection of different types of targets was presented. In particular, two targets in air, metal sphere and cylinder of water and gelatin, and on two targets (cylinder of water and gelatin, and currant) included in two different phantoms (oil and waste-oil hardener, and Polysorbate80 and waste-oil hardener), deep up to 2 cm below the surface of the phantom were used to test the mm-wave imaging prototype. The synthetic array was composed of 24 antennas in 28 positions, with spacing between phase centers of adjacent radiators equal to half wavelength in air at 30 GHz, 5mm. The results showed that the proposed system is able to correctly identify the position of the target in both scenarios, in air and in phantom, with sub-cm resolutions in both cases. Then, in this year, the proof of concept of the feasibility of the imaging system with central working frequency of around 30 GHz for the early detection of breast cancer was demonstrated.
Therefore, in conclusion, in this Ph.D. Thesis, the feasibility of a system of this type for applications of screening and possibly diagnosis for breast cancer in women whose breasts lend themselves to scanning with mammography is demonstrated in many respects, strongly encouraging further analysis in this direction
Dosimetric Analysis of Plane Wave Propagation in Biological Tissues: Comparison Between Planar Multilayer vs Realistic Anatomical Models
No full textNumerical exposure to realistic and planar body models: effect of the polarization
No full textIn this paper, a comparison of the electromagnetic field induced by plane wave exposure with circular and linear polarization on an anthropomorphic human body model is shown. The same exposure was reproduced on a multilayer model. In particular, the anatomical region of the arm is analyzed and the frequency of 24 GHz is considered. The software used for these two sets of simulations are Ansys HFSS (for the multilayer slab model) and Sim4Life (for the anatomical model). The results show that differences in the EM field distribution (comparing the different polarization conditions) are visible with the 3-D simulations on anatomical models, while the layered model, as expected, is not sensitive to the change of polarization of the wave with normal incidence on the layering
Preliminary Experimental Characterization of Gelatin-Based Tissue-Mimicking Materials for Realistic Breast Phantoms aimed at Microwave Applications
No full textBreast cancer is the most aggressive and common cause of death among women around the world, and an early diagnosis is fundamental to increase the survival chances. Microwave and mm-wave imaging systems have been recently proposed as a possible technique for cancer detection, on the grounds of the different dielectric permittivity between healthy and neoplastic tissues. To support the experimental development of such systems, phantoms able to mimic the different dielectric permittivity are required. In addition, the possibility to provide, at the same time, mechanical properties similar to those of real tissues would be beneficial to deliver phantoms as realistic as possible. In this paper, two simple and easy-to-produce mixtures able to mimic the dielectric properties of neoplastic breast tissue are presented; their dielectric properties are compared to the ones derived from human neoplastic ex-vivo samples and their mechanical properties are tested. In particular, two different percentages of gelling material are used and both the dielectric and mechanical material properties are measured, demonstrating the possibility to tune the Young's module of the samples
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Microwave Bone Imaging: Reconstruction of Anthropomorphic Numerical Calcaneus Phantoms for Bone Diseases Diagnosis
No full textMicrowave Tomography (MWT) is emerging as a potential imaging technique for monitoring bone health due to its ability to determine the dielectric properties of tissues under investigation. Studies have demonstrated a significant dielectric contrast between healthy and diseased human trabecular bones, which suggests that MWT has the potential to detect changes associated with bone disorders. The goal of this study was to assess the numerical reconstruction of an anthropomorphic two-layer (cortical and trabecular bone) calcaneus-shaped phantom, considering both healthy and diseased scenarios. Data were obtained using two different antenna configurations: a 16-antenna circular array and a 24-antenna calcaneus-shaped array. The electromagnetic (EM) inverse problem was solved by employing the Distorted Born Iterative Method (DBIM) in conjunction with the Iterative Method with Adaptive Thresholding for Compressed Sensing (IMATCS). An L-2-based regularization method was applied along with the IMATCS. The results demonstrated that accurate reconstruction of various phantom properties at 1 GHz is feasible even under low signal-to-noise ratio (SNR) conditions. The achieved results suggest that the present approach can provide a good numerical reconstruction of the proposed phantoms both in the circular array and the calcaneus-shaped array scenarios, proving its robustness in distinguishing the overall reference and reconstructed dielectric properties with an average percentage difference of 10.43%. This work revealed the possibility of applying the suggested approach in a new scenario with a realistic phantom in two different antenna-array geometric configurations. In the future, this could be tested in an experimental context to assess the medical conditions of the human bones
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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