The best way to conquer breast cancer is early detection of the disease. Research studies show that earlier detection results in the increase of life span of the affected person. Traditional two-dimensional mammography is the most prevalent method used in detecting breast cancer. Recently, a three-dimensional digital breast tomosynthesis (DBT) system has been created, which is hopeful to surpass the technology of traditional mammography systems. The DBT system can provide three-dimensional information, allowing physicians to reduce the amount of false negative screening in addition to better monitoring of breast cancer and to catch lesions that may be otherwise cancerous. In this research, the View Angle (VA) and number of projection images (N) were investigated and compared with parallel imaging configurations using two reconstruction algorithms, including Back Projection (BP) and Shift-And-Add (SAA). Modulation Transfer Function (MTF) analyses were conducted with both algorithms, in order to determine which method displayed better image qualities to ultimately improve the detection of breast cancer.

Demographic data indicate that 60% of 6.7 million annual global cancer mortalities and 54% of 10.8 million new patients are in developing nations, unable or unwilling to avail of invasive screening tests that are the current norm. For most cancers, survival rate is strongly dependent on early detection, highlighting the need for improved screening methods. Studies have shown that cancers can be identified based on distinct sub-cellular morphological features and expression levels of specific molecular markers. Since 85% of cancers are known to originate in the epithelium, portable in vivo imaging techniques providing sub-cellular detail in tissue up to depths of 250 μm could help improve access to biopsy-free examination in low-infrastructure environments. The resultant early detection could dramatically improve patient prognosis, while reducing screening costs, treatment delay, and occurrences of unnecessary and potentially harmful medication. This dissertation investigates handheld instrumentation for laser-scanning confocal microscopy (LSCM) and its applicability to breast cancer detection and subsequent image-guided management. LSCM allows high-resolution mapping of spatial variations in refractive index or tumor marker expression within a single cell layer situated few hundred micrometers beneath the tissue surface. The main challenge facing miniaturization lies in the mechanism of beam deflection across the sample. The first part of the dissertation presents a fast, large-angle, high-reflectivity two-axis vertical comb driven silicon micromirror fabricated by a novel method compatible with complementary metal-oxide-semiconductor processing employed in the semiconductor industry. The process enables integration of rotation sensors on the chip to adaptively correct for aberrations in beam scanning while significantly reducing fabrication costs and barriers to market acceptance. The second part of the dissertation explores the integration of this micromirror with other optical and electronic components into a handheld laser-scanning confocal microscope. Applicability of the probe to epithelial breast cancer screening via reflectance and fluorescence imaging is investigated. Finally, enhanced imaging modalities based on the micromirror are presented. 3D cellular-level in vivo imaging via rapid swept-source optical coherence tomography is demonstrated. A method for “objective-less” microendoscopy, potentially resulting in substantially reduced probe dimensions, employing reflective binary-phase Fresnel zone plates monolithically integrated on the surface of the micromirror is presented. / text

The statistical evaluation of molecular imaging approaches for detecting, diagnosing, and monitoring molecular response to treatment are required prior to their adoption. The assessment of fluorescence-enhanced optical imaging is particularly challenging since neither instrument nor agent has been established. Small animal imaging does not address the depth of penetration issues adequately and the risk of administering molecular optical imaging agents into patients remains unknown. Herein, we focus upon the development of a framework for OAIQ which includes a lumpy-object model to simulate natural anatomical tissue structure as well as the non-specific distribution of fluorescent contrast agents. This work is required for adoption of fluorescence-enhanced optical imaging in the clinic. Herein, the imaging system is simulated by the diffusion approximation of the time-dependent radiative transfer equation, which describes near infra-red light propagation through clinically relevant volumes. We predict the time-dependent light propagation within a 200 cc breast interrogated with 25 points of excitation illumination and 128 points of fluorescent light collection. We simulate the fluorescence generation from Cardio-Green at tissue target concentrations of 1, 0.5, and 0.25 µM with backgrounds containing 0.01 µM. The fluorescence boundary measurements for 1 cc spherical targets simulated within lumpy backgrounds of (i) endogenous optical properties (absorption and scattering), as well as (ii) exogenous fluorophore crosssection are generated with lump strength varying up to 100% of the average background. The imaging data are then used to validate a PMBF/CONTN tomographic reconstruction algorithm. Our results show that the image recovery is sensitive to the heterogeneous background structures. Further analysis on the imaging data by a Hotelling observer affirms that the detection capability of the imaging system is adversely affected by the presence of heterogeneous background structures. The above issue is also addressed using the human-observer studies wherein multiple cases of randomly located targets superimposed on random heterogeneous backgrounds are used in a “double-blind” situation. The results of this study show consistency with the outcome of above mentioned analyses. Finally, the Hotelling observer’s analysis is used to demonstrate (i) the inverse correlation between detectability and target depth, and (ii) the plateauing of detectability with improved excitation light rejection.

Thesis (MSc (Radiography))--Cape Peninsula University of Technology, 2019 / INTRODUCTION: The Breast Imaging Reporting and Data System (BI-RADS) was developed by the American College of Radiology (ACR). The BI-RADS is an internationally accepted method of assessing and reporting on mammograms and breast ultrasound images. The BI-RADS consists of a lexicon (descriptors) and assessment categories. The ACR aimed to standardise mammography reporting and placing the findings in the appropriate assessment category. The aim of this study was to establish the accuracy of the BI-RADS assessment categories for mammography and breast ultrasound images in women diagnosed with breast cancer. METHOD: Data were retrieved from 77 patients who were diagnosed with breast cancer from 1 January 2013 to 31 December 2014. Seven did not meet the inclusion criteria and were excluded. The study sample size was 70 (n=70) patients. All mammography reports included a BI-RADS assessment category of all patients diagnosed with breast cancer within the study period. These reports were analysed and compared with histopathology results. The BI-RADS assessment category and descriptors were collected from the mammogram reports; the histopathology report indicated the type of breast cancer. All reports were obtained from the patients' folders at the research site. In addition, questionnaires were distributed among radiologists to assess whether their experience and training had an influence on the accuracy of reporting in the BI-RADS assessment categories. Descriptive and inferential statistical analysis was used for data analysis. RESULTS: The most common malignancy diagnosed was invasive ductal carcinoma with a total of 70% (n=54), followed by ductal carcinoma in situ with 10.4% (n=8) and invasive lobular carcinoma with 9.1% (n=7). The histology results confirmed breast cancer for all BI-RADS 4 and 5 assessment categories. The mammogram was able to detect 93.5% of abnormalities and breast ultrasound 84.4% of abnormalities in this study sample. Breast ultrasound was used as an adjunct to mammography and hence an overall combined diagnostic rate was 100%. Mammography descriptors: The more common malignancy findings were spiculated mass margin, 35.1% (n=27). Ultrasound descriptors: The more common malignancy findings were hypoechoic echo pattern, 55.8% (n=43). There was no significant association (p=0.152) between the radiologists' years of experience and BI-RADS 3, 4 and 5 assessment category reporting. Of the 15 responses, 67% agreed that the BI-RADS standardises breast imaging reporting and reduces confusion, 33% agreed that the BI-RADS allows better communication between radiologists and referring physicians, and 40% agreed that the BI-RADS clarifies further management for patients by helping to stratify risk management. CONCLUSION: The outcome of this study indicated that the use of BI-RADS assessment categories is useful for predicting the likelihood of malignancy when used correctly. The outcome of BI-RADS 4 and BI-RADS 5 had a positive predictive value of 100%, which corresponded well with histology results. The descriptor findings suggested that spiculated mass margins, irregular-shaped masses, hypoechoic echo pattern and posterior shadowing were high predictors of malignancy and warranted a placement in the BI-RADS 5 assessment category.

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During a clinical breast exam, a doctor palpates the breast and uses factors such as estimated size and stiffness of subcutaneous inclusions to determine whether they may be malignant tumors. The Tactile Imaging System (TIS) under development at the Control, Sensing, Networking and Perception Laboratory (CSNAP) is an effort to provide accurate and consistent characterization of inclusions. The sensing principle of the TIS is based on Total Internal Reflection (TIR) of light in a Polydimethylsiloxane (PDMS) optical waveguide positioned in front of a digital camera. When the PDMS is pressed against an object of greater stiffness it deforms, causing some light to escape the waveguide and be sensed by the camera. An algorithm maps the light pattern caused by the deformation and the force applied during the image acquisition to estimate the size, depth and stiffness of the inclusion based on a kernel model. The Third Generation Experimental TIS (TIS 3E) is an effort to improve the performance, repeatability, and usability of the system. Performance is increased through a new graphical user interface (GUI) allowing fine tuning of camera parameters, and interchangeable sensing probes for varying PDMS waveguides. Repeatability is improved with a digitally controlled lighting system, hardware triggered force sensing, and an online PDMS lighting and condition monitoring system, lowering the overall measurement error of the system. Usability is improved by a new chassis, reducing the device size and weight by 50 percent. Accuracy of the TIS 3E is comparable to the maximum accuracy TIS 1E, and exceeded the minimum accuracy of the TIS 1E. The measurement frequency was also increased from 10Hz to 50Hz. The TIS 3E will provide an accurate, consistent data acquisition platform for future Tactile Imaging Research efforts. / Electrical and Computer Engineering

Ce travail concerne l'imagerie micro-onde en vue d'application à l'imagerie biomédicale. Cette technique d'imagerie a pour objectif de retrouver la distribution des propriétés diélectriques internes (permittivité diélectrique et conductivité) d'un objet inconnu illuminé par une onde interrogatrice connue à partir des mesures du champ électrique dit diffracté résultant de leur interaction. Un tel problème constitue un problème dit inverse par opposition au problème direct associé qui consiste à calculer le champ diffracté, l'onde interrogatrice et l'objet étant alors connus.La résolution du problème inverse nécessite la construction préalable du modèle direct associé. Celui-ci est ici basé sur une représentation intégrale de domaine des champs électriques donnant naissance à deux équations intégrales couplées dont les contreparties discrètes sont obtenues à l'aide de la méthode des moments. En ce qui concerne le problème inverse, hormis le fait que les équations physiques qui interviennent dans sa modélisation directe le rendent non-linéaire, il est également mathématiquement mal posé au sens de Hadamard, ce qui signifie que les conditions d'existence, d'unicité et de stabilité de la solution ne sont pas simultanément garanties. La résolution d'un tel problème nécessite sa régularisation préalable qui consiste généralement en l'introduction d'information a priori sur la solution recherchée. Cette résolution est effectuée, ici, dans un cadre probabiliste bayésien où l'on introduit une connaissance a priori adaptée à l'objet sous test et qui consiste à considérer ce dernier comme étant composé d'un nombre fini de matériaux homogènes distribués dans des régions compactes. Cet information est introduite par le biais d'un modèle de « Gauss-Markov-Potts ». De plus, le calcul bayésien nous donne la distribution a posteriori de toutes les inconnues connaissant l'a priori et l'objet. On s'attache ensuite à déterminer les estimateurs a posteriori via des méthodes d'approximation variationnelles et à reconstruire ainsi l'image de l'objet recherché. Les principales contributions de ce travail sont d'ordre méthodologique et algorithmique. Elles sont illustrées par une application de l'imagerie micro-onde à la détection du cancer du sein. Cette dernière constitue en soi un point très important et original de la thèse. En effet, la détection du cancer su sein en imagerie micro-onde est une alternative très intéressante à la mammographie par rayons X, mais n'en est encore qu'à un stade exploratoire. / This work concerns the problem of microwave tomography for application to biomedical imaging. The aim is to retreive both permittivity and conductivity of an unknown object from measurements of the scattered field that results from its interaction with a known interrogating wave. Such a problem is said to be inverse opposed to the associated forward problem that consists in calculating the scattered field while the interrogating wave and the object are known. The resolution of the inverse problem requires the prior construction of the associated forward model. This latter is based on an integral representation of the electric field resulting in two coupled integral equations whose discrete counterparts are obtained by means of the method of moments.Regarding the inverse problem, in addition to the fact that the physical equations involved in the forward modeling make it nonlinear, it is also mathematically ill-posed in the sense of Hadamard, which means that the conditions of existence, uniqueness and stability of the solution are not simultaneously guaranteed. Hence, solving this problem requires its prior regularization which usually involves the introduction of a priori information on the sought solution. This resolution is done here in a Bayesian probabilistic framework where we introduced a priori knowledge appropriate to the sought object by considering it to be composed of a finite number of homogeneous materials distributed in compact and homogeneous regions. This information is introduced through a "Gauss-Markov-Potts" model. In addition, the Bayesian computation gives the posterior distribution of all the unknowns, knowing the a priori and the object. We proceed then to identify the posterior estimators via variational approximation methods and thereby to reconstruct the image of the desired object.The main contributions of this work are methodological and algorithmic. They are illustrated by an application of microwave imaging to breast cancer detection. The latter is in itself a very important and original aspect of the thesis. Indeed, the detection of breast cancer using microwave imaging is a very interesting alternative to X-ray mammography, but it is still at an exploratory stage.

L'objectif général est de développer un nouvel outil numérique dédié à la focalisation en 3D de l'énergie en zone de champ très proche par un système antennaire. Cet outil permettra de définir la distribution spatiale complexe des champs dans l'ouverture rayonnante afin de focaliser l'énergie sur un volume quelconque en zone de champ réactif. L'hybridation de cet outil avec un code de calcul dédié à l'analyse rapide d‘antennes SIW par la méthode des moments permettra de synthétiser une antenne SIW ad-hoc. Les structures antennaires sélectionnées seront planaires comme par exemple les antennes RLSA (Radial Line Slot Array). Les dimensions de l'antenne (positions, dimensions et nombre de fentes) seront définies à l'aide des outils décrits ci-dessus. Les résultats numériques ainsi obtenus seront validés d'abord numériquement par analyse électromagnétique globale à l'aide de simulateurs commerciaux, puis expérimentalement en ondes millimétriques (mesure en zone de champ très proche). Pour atteindre ces objectifs, nous avons défini quatre tâches principales : Développement d'un outil de synthèse de champ dans l'ouverture rayonnante (formulation théorique couplée à une méthode dite des projections alternées) ; développement d'un outil de calcul rapide (sur la base de traitements par FFT) du champ électromagnétique rayonné en zone de champ proche par une ouverture rayonnante, et retro-propagation ; hybridation de ces algorithmes avec un code de calcul (méthode des moments) en cours de développement à l'IETR et dédié à l'analyse très rapide d'antennes en technologie SIW ; conception d'une preuve ou plusieurs preuves de concept, et validations numérique et expérimentale des concepts proposés. / With the demand for near-field antennas continuously growing, the antenna engineer is charged with the development of new concepts and design procedures for this regime. From the microwave and up to terahertz frequencies, a vast number of applications, especially in the biomedical domain, are in need for focused or shaped fields in the antenna proximity. This work proposes new theoretical methods for near-field shaping based on different optimization schemes. Continuous radiating planar apertures are optimized to radiate a near field with required characteristics. In particular, a versatile optimization technique based on the alternating projection scheme is proposed. It is demonstrated that, based on this scheme, it is feasible to achieve 3-D control of focal spots generated by planar apertures. Additionally, with the same setup, also the vectorial problem (shaping the norm of the field) is addressed. Convex optimization is additionally introduced for near-field shaping of continuous aperture sources. The capabilities of this scheme are demonstrated in the context of different shaping scenarios. Additionally, the discussion is extended to shaping the field in lossy stratified media, based on a spectral Green's functions approach. Besides, the biomedical applications of wireless power transfer to implants and breast cancer imaging are addressed. For the latter, an extensive study is included here, which delivers an outstanding improvement on the penetration depth at higher frequencies. The thesis is completed by several prototypes used for validation. Four different antennas have been designed, based either on the radial line slot array topology or on metasurfaces. The prototypes have been manufactured and measured, validating the overall approach of the thesis.