A Comprehensive Review on Design and Development of Human Breast Phantoms for Ultra-Wide Band Breast Cancer Imaging Systems

Microwave ultra-wide band UWB imaging system is a contemporary biomedical imaging technology for early detection of breast cancers. This imaging system requires the development of breast phantoms for experimental data analysis. In order to obtain realistic results, it is very important that these phantoms mimic the characteristics of real biological breast tissue as close as possible. For this purpose, scientists and engineers make use of the dielectric properties of human breast. This paper takes a survey of mathematical formulations used to determine biological dielectric properties and then takes a review of current breast phantoms being used in UWB imaging systems with reference to the analytical dielectric measurements. At present, breast phantoms are made, both, manually in laboratory utilizing different chemicals and also by using computational electromagnetic algorithms to introduce better heterogeneity in them. They can then easily be tested by doing computer simulations. In this review paper, emphasis is made on the phantoms which are made in laboratory for doing hardware experimentations.Microwave ultra-wide band UWB imaging system is a contemporary biomedical imaging technology for early detection of breast cancers. This imaging system requires the development of breast phantoms for experimental data analysis. In order to obtain realistic results, it is very important that these phantoms mimic the characteristics of real biological breast tissue as close as possible. For this purpose, scientists and engineers make use of the dielectric properties of human breast. This paper takes a survey of mathematical formulations used to determine biological dielectric properties and then takes a review of current breast phantoms being used in UWB imaging systems with reference to the analytical dielectric measurements. At present, breast phantoms are made, both, manually in laboratory utilizing different chemicals and also by using computational electromagnetic algorithms to introduce better heterogeneity in them. They can then easily be tested by doing computer simulations. In this review paper, emphasis is made on the phantoms which are made in laboratory for doing hardware experimentations

Ultrawideband Technology for Medical In-Body Sensor Networks: An Overview of the Human Body as a Propagation Medium, Phantoms, and Approaches for Propagation Analysis

[EN] An in-body sensor network is that in which at least one of the sensors is located inside the human body. Such wireless in-body sensors are used mainly in medical applications, collecting and monitoring important parameters for health and disease treatment. IEEE Standard 802.15.6-2012 for wireless body area networks (WBANs) considers in-body communications in the Medical Implant Communications Service (MICS) band. Nevertheless, high-data-rate communications are not feasible at the MICS band because of its narrow occupied bandwidth. In this framework, ultrawideband (UWB) systems have emerged as a potential solution for in-body highdata-rate communications because of their miniaturization capabilities and low power consumption.This work was supported by the Programa de Ayudas de Investigación y Desarrollo (PAID-01-16) at the Universitat Politècnica de València, Spain; by the Ministerio de Economía y Competitividad, Spain (TEC2014-60258-C2-1-R); and by the European FEDER funds. It was also funded by the European Union’s H2020:MSCA:ITN program for the Wireless In-Body Environ-ment Communication–WiBEC project under grant 675353.Garcia-Pardo, C.; Andreu-Estellés, C.; Fornés Leal, A.; Castelló-Palacios, S.; Pérez-Simbor, S.; Barbi, M.; Vallés Lluch, A.... (2018). Ultrawideband Technology for Medical In-Body Sensor Networks: An Overview of the Human Body as a Propagation Medium, Phantoms, and Approaches for Propagation Analysis. IEEE Antennas and Propagation Magazine. 60(3):19-33. https://doi.org/10.1109/MAP.2018.2818458S193360

Development of an Anthropomorphic Phantom of the Axillary Region for Microwave Imaging Assessment

We produced an anatomically and dielectrically realistic phantom of the axillary region to enable the experimental assessment of Axillary Lymph Node (ALN) imaging using microwave imaging technology. We segmented a thoracic Computed Tomography (CT) scan and created a computer-aided designed file containing the anatomical configuration of the axillary region. The phantom comprises five 3D-printed parts representing the main tissues of interest of the axillary region for the purpose of microwave imaging: fat, muscle, bone, ALNs, and lung. The phantom allows the experimental assessment of multiple anatomical configurations, by including ALNs of different size, shape, and number in several locations. Except for the bone mimicking organ, which is made of solid conductive polymer, we 3D-printed cavities to represent the fat, muscle, ALN, and lung and filled them with appropriate tissue-mimicking liquids. Existing studies about complex permittivity of ALNs have reported limitations. To address these, we measured the complex permittivity of both human and animal lymph nodes using the standard open-ended coaxial-probe technique, over the 0.5 GHz-8.5 GHz frequency band, thus extending current knowledge on dielectric properties of ALNs. Lastly, we numerically evaluated the effect of the polymer which constitutes the cavities of the phantom and compared it to the realistic axillary region. The results showed a maximum difference of 7 dB at 4 GHz in the electric field magnitude coupled to the tissues and a maximum of 10 dB difference in the ALN response. Our results showed that the phantom is a good representation of the axillary region and a viable tool for pre-clinical assessment of microwave imaging technology.info:eu-repo/semantics/publishedVersio

Microwave Imaging for Diagnostic Application

Imaging of the human body makes a significant contribution to the diagnosis and succeeding treatment of diseases. Among the numerous medical imaging methods, microwave imaging (MWI) is an attractive approach for medical applications due to its high potential to produce images of the human body safely with cost-efficiency. A wide range of studies and research has been done with the aim of using the microwave approach for medical applications. The focus of this research is developing MWI algorithms, which is the Huygens Principle (HP) based and to validate the capability of the proposed MWI algorithm to detect skin cancer and bone lesion through phantom measurements. The probability of the HP procedure for skin cancer detection has been investigated through design, and fabrication of a heterogeneous phantom simulating the human forearm having an inclusion mimicking a skin cancer. Ultrawideband (UWB) MWI methods are then applied to the phantom. The S21 parameter measurements are collected in an anechoic chamber environment and processed via HP technique. The tumour is successfully detected after applying appropriate artefact removal procedure. The ability to successfully apply HP to detect and locate a skin cancer type inclusion in a multilayer cylindrical phantom has been verified. The feasibility study of HP-based MWI procedure for bone lesion detection has also been investigated using a dedicated phantom. Validation has been completed through measurements inside the anechoic chamber in the frequency range of 1–3 GHz using one receiving and one transmitting antennas in free space. The identification of the lesion’s presence in different bone layers has been performed on images. The quantification of the obtained images has been performed by introducing parameters such as the resolution and signal-to-clutter ratio (S/C). The impact of different frequencies and bandwidths (in the 1–3 GHz range) in lesion detection has been investigated. The findings showed that the frequency range of 1.5–2.5 GHz offered the best resolution (1.1 cm) and S/C (2.22 on a linear scale). Subtraction between S21 obtained using two slightly displaced transmitting positions has been employed to remove the artefacts; the best artefact removal has been obtained when the spatial displacement was approximately of the same magnitude as the dimension of the lesion. Subsequently, a phantom validation of a low complexity MWI device (based on HP) operating in free space in the 1-6.5 GHz frequency band using two antennas in free space has been applied. Detection has been achieved in both bone fracture lesion and bone marrow lesion scenarios using superimposition of five doublet transmitting positions after applying the rotation subtraction method to remove artefact. A resolution of 5 mm and the S/C (3.35 in linear scale) are achieved which is clearly confirming the advantage of employing multiple transmitting positions on increased detection capability. The finding of this research verifies the dedicated MWI device as a simple, safe and without any X-ray radiation, portable, and low complexity method, which is capable of been successfully used for bone lesion detection. The outcomes of this thesis may pave the way for the construction of a dedicated bone imaging system that in future could be used as a safe diagnostic device even in emergency sites

Wideband Electromagnetic Body Phantoms for the Evaluation of Wireless Communications in the Microwave Spectrum

[ES] La constante evolución de la tecnología y la búsqueda de nuevas aplicaciones que mejoren la vida de las personas ha llevado a la incorporación de estas tecnologías en el organismo. Las redes inalámbricas de área corporal (WBAN) son un buen ejemplo de esto, que consisten en redes de comunicaciones ubicadas en el propio cuerpo, tanto en la superficie como implantadas en su interior mediante el uso de dispositivos inalámbricos. Estas redes utilizan el cuerpo humano como medio de transmisión, por lo que debe evaluarse la influencia del mismo sobre la propagación. Además, las nuevas generaciones de comunicaciones móviles se están moviendo hacia el uso de frecuencias cada vez más altas, como las ondas milimétricas, que son más sensibles a la presencia de cualquier objeto en el entorno, incluidos los humanos. La investigación y el diseño de antenas y dispositivos que tengan en cuenta el cuerpo humano requiere pruebas en el entorno donde se supone que deben usarse. Los fantomas se convierten en una herramienta para evaluar la transmisión de señales electromagnéticas en un medio equivalente al cuerpo para evitar la experimentación en humanos o animales. Además de eso, se puede estudiar la influencia de estas ondas electromagnéticas sobre los propios tejidos en cuanto a la tasa de absorción específica (SAR).[CA] L'evolució constant de la tecnologia i la recerca de noves aplicacions que milloren la vida de les persones ha portat a la incorporació d'aquestes tecnologies en l'organisme. Les xarxes sense fils d'àrea corporal (WBAN) són un bon exemple d'açò, que consisteixen en xarxes de comunicacions ubicades al propi cos, tant en la superfície com implantades en el seu interior mitjançant l'ús de dispositius sense fils. Aquestes xarxes empren el cos humà com a medi de transmissió, per la qual cosa se n'ha d'avaluar la influència sobre la propagació. A més, les noves generacions de comunicacions mòbils s'estan movent cap a l'ús de freqüències cada vegada més altes, com les ones mil·limètriques, que són més sensibles a la presència de qualsevol objecte en l'entorn, incloent-hi els humans. La investigació i el disseny d'antenes i dispositius que tinguen en compte el cos humà requereix proves en l'entorn on se suposa que han d'usar-se. Els fantomes esdevenen una eina per a avaluar la transmissió de senyals electromagnètics en un medi equivalent al cos per tal d'evitar l'experimentació en humans o animals. A més d'això, es pot estudiar la influència d'aquestes ones electromagnètiques sobre els teixits mateixos en relació amb la taxa d'absorció específica (SAR).[EN] The constant evolution of technology and the search for new applications that improve people's lives has led to the arrival of the incorporation of these technologies in the organism. Wireless body area networks (WBANs) are a good example of this, consisting of communications networks located in the body itself, both on the surface and implanted inside it through the use of wireless devices. These networks use the human body as the transmitting medium, so its influence over the propagation has to be assessed. Besides, new generations of mobile communications are moving towards the use of higher frequencies, as the millimetre waves, which are more sensitive to the presence of any object in the environment, including humans. The research and design of antennas and devices that take into account the human body requires testing in the environment where these are supposed to be used. Phantoms become a tool for evaluating the transmission of electromagnetic signals in a body-equivalent medium in order to avoid experimentation on humans or animals. In addition to that, the influence of these electromagnetic waves over the tissues themselves can be studied with regard to the specific absorption rate (SAR).This thesis has been possible thanks to the funding contribution of the Universitat Polit`ecnica de Val`encia through the PAID-01-16 programme. This work was also supported by the UPV-IIS La Fe programme (STUDER, 2016 and EMOTE, 2017). The research stay was supported by the European Union’s Erasmus+ funding programme under a traineeship grant.Castelló Palacios, S. (2019). Wideband Electromagnetic Body Phantoms for the Evaluation of Wireless Communications in the Microwave Spectrum [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/13218

Radar-based breast cancer detection using a hemispherical antenna array - experimental results

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Microwave breast imaging using a dry setup

This article demonstrates for the first time, both numerically and experimentally, the feasibility of radar-based microwave imaging of anthropomorphic heterogeneously dense breasts in prone position, requiring no immersion liquid. The dry, contactless approach greatly simplifies the setup, favors patient comfort, and further avoids lengthy sanitation procedures after each exam. We use a radar-type technique with the antennas distributed in cylindrical configuration around the breast phantom. The reflectivity map is reconstructed using a wave-migration algorithm in the frequency domain. This article presents new developed strategies to cope with the challenges of a dry setup, namely increased skin artifact due to the concomitant absence of matching liquid and nonuniform breast shape. We propose an iterative and adaptive algorithm based on singular value decomposition that effectively removes the skin backscattering under the abovementioned conditions. It is compatible with automatic processing, and computationally fast. One of its inputs is the breast three-dimensional surface information, and its distance to the antennas, all obtained automatically from a proposed low-cost procedure based on a webcam. The imaging method is reasonably resilient to the presence of fibroglandular tissues, and to uncertainties of tissue permittivity. Another tackled challenge is the miniaturization of the antenna in air, which is achieved with an optimized balanced antipodal Vivaldi of the same size as counterparts used in dense immersion liquids. Finally, all the building blocks are combined to demonstrate experimentally the overall dry system performance, with very good detection of the tumor at three different positions in the breast, even in low-contrast scenarios.info:eu-repo/semantics/acceptedVersio

Ultra-wideband antennas

The focus of UWB antenna research activity has matured in recent years and currently mainly concentrates on applications such as biomedicine and security. Early UWB antenna designs were driven by the FCC allocation of spectrum in 2002 and focussed on obtaining wide impedance bandwidths with reasonable group delay characteristics. Many of these were simple planar monopoles antennas with canonical geometries. The emergence of new applications channelled the emphasis towards miniaturisation and integration into devices. This required optimisation of the antenna geometries to ensure that good system performance is achieved from the integrated antenna. Many optimisation techniques are available including the spline technique to generate the outline of the antenna element and ground plane. Simple methods based on genetic algorithms are employed and evolutionary algorithms which are capable of optimising for multiple goals are beneficial when multiple antenna parameters are simultaneously investigated. These techniques have proven advantageous especially when time-domain performance is critical and provide solutions for both single-ended and differential feed arrangements. The main applications using UWB channels in the 3.1 GHz −10.6 GHz spectrum are localization and tracking applications, mainly employing impulse radio UWB imaging, and generally using linear polarization. However circularly-polarized UWB antennas have been developed, both directional and omnidirectional and are being investigated across various systems

Application-Specific Broadband Antennas for Microwave Medical Imaging

The goal of this work is the introduction of efficient antenna structures on the basis of the requirement of different microwave imaging methods; i.e. quantitative and qualitative microwave imaging techniques. Several criteria are proposed for the evaluation of single element antenna structures for application in microwave imaging systems. The performance of the proposed antennas are evaluated in simulation and measurement scenarios