An approximate of the Green's function can be obtained by taking the cross-correlation of ambient noise that has been simultaneously recorded on separate sensors. This method is applied for two experiments, which illustrate the advantages and challenges of this technique. The first experiment is in the ultrasonic regime [5-30] MHz and uses capacitive micromachined ultrasonic transducer arrays to image the near field and compares the passive imaging to the conventional pulse-echo imaging. Both the array and target are immersed in a fluid with the sensors recording the fluid's random thermal-mechanical motion as the ambient noise. The second experiment is a passive ocean monitoring experiment, which uses spatiotemporal filtering to rapidly extract coherent arrivals between two vertical line arrays. In this case the ambient noise in the frequency band [250 1500] Hz is dominated by non-stationary shipping noise. For imaging purposes, the cross-correlation needs to extract the Green's function so that the imaging can be done correctly. While for monitoring purposes, the important feature is the change in arrivals, which corresponds to the environment changing. Results of both experiments are presented along with the advantages of this passive method over the more accepted active methods.

The utility of microbubble agents in a variety of diagnostic and therapeutic ultrasound techniques has been widely demonstrated, most notably in Contrast Enhanced Ultrasound (CEUS) imaging. Unfortunately, the underlying mechanisms of their response to ultrasound excitation are poorly understood, restricting the development of promising techniques, such as quantitative perfusion imaging. A significant reason for this is that current microbubble characterisation techniques suffer from one or more of the following limitations: i) large experimental uncertainties, ii) physical restrictions on microbubble response and iii) failure to provide large data sets suitable for statistical analysis. This thesis presents a new technique to overcome these limitations. A co-axial microfluidic device is used to hydrodynamically confine microbubbles through the focal region of a laser and ultrasound field. The magnitude of light scattered by isolated microbubbles during ultrasound excitation is converted to radius using Mie Scattering theory. This technique is capable of obtaining large samples (>10³/min) of microbubbles to be efficiently characterised. The response of a commercial contrast agent, SonoVue®, is first investigated for a range of ultrasound exposure parameters; frequency (2 MHz - 4.5 MHz), peak negative pressure (6 kPa - 400 kPa) and pulse length (3 cycles - 8 cycles). Second the device is used to investigate the effect of composition and fabrication on microbubble response to similar ultrasound conditions. The results demonstrate a very large variability in microbubble response independent of initial size, indicating a significant lack of uniformity of coating properties. This is further supported by quantitative fluorescence imaging and quasi-static pressure chamber measurements. The implications of the findings for CEUS imaging and the development of microbubble contrast agents are discussed, as well as the limitations and suggested improvements of the characterisation technique.

Les systèmes d’imagerie médicale ultrasonore ont considérablement amélioré le diagnostic clinique par une meilleure qualité des images grâce à des systèmes plus sensibles et des post-traitements. La communauté scientifique de l’imagerie ultrasonore a consenti à un très grand effort de recherche sur les posttraitements et sur le codage de l’excitation sans s’intéresser, outre mesure, aux méthodes de commandeoptimale. Ce travail s’est donc légitimement tourné vers les méthodes optimales basées sur l’utilisationd’une rétroaction de la sortie sur l’entrée. Pour rendre applicable ces méthodes, ce problème complexe decommande optimale a été transformé en un problème d’optimisation paramétrique sous-optimal et plussimple. Nous avons appliqué ce principe au domaine de l’imagerie ultrasonore : l’échographie, l’imagerieharmonique native et l’imagerie harmonique de contraste avec ou sans codage de la commande.La simplicité de l’approche nous a permis, par une modification de la fonction de coût, de l’adapter àl’imagerie harmonique. Cette adaptation montre que la méthode peut être appliquée à l’imagerie ultrasonoreen générale. / Medical ultrasound imaging systems have greatly improved the clinical diagnosis by improvingthe image quality thanks to more sensitive systems and post-processings. The scientific community has madea great effort of research on post-processing and on encoding the excitation. The methods of the optimalcontrol have been neglected. Our work has focused on the optimal methods based on the feedback fromoutput to input. We have transformed the complex problem of optimal control into an easier suboptimalparametric problem. We apply the principle of optimal control to the ultrasound imaging, the ultrasoundharmonic imaging and to the constrast harmonic imaging with or without encoding.The simplicity of the method has allowed us to adapt it to harmonic imaging by a change in the costfunction. This adaptation shows that our method can usually be applied to the ultrasound imaging.

L'imagerie ultrasonore (US) permet de réaliser des examens médicaux non invasifs avec des méthodes d'acquisition rapides à des coûts modérés. L'imagerie cardiaque, abdominale, fœtale, ou mammaire sont quelques-unes des applications où elle est largement utilisée comme outil de diagnostic. En imagerie US classique, des ondes acoustiques sont transmises à une région d'intérêt du corps humain. Les signaux d'écho rétrodiffusés, sont ensuite formés pour créer des lignes radiofréquences. La formation de voies (FV) joue un rôle clé dans l'obtention des images US, car elle influence la résolution et le contraste de l'image finale. L'objectif de ce travail est de modéliser la formation de voies comme un problème inverse liant les données brutes aux signaux RF. Le modèle de formation de voies proposé ici améliore le contraste et la résolution spatiale des images échographiques par rapport aux techniques de FV existants. Dans un premier temps, nous nous sommes concentrés sur des méthodes de FV en imagerie US. Nous avons brièvement passé en revue les techniques de formation de voies les plus courantes, en commencent par la méthode par retard et somme standard puis en utilisant les techniques de formation de voies adaptatives. Ensuite, nous avons étudié l'utilisation de signaux qui exploitent une représentation parcimonieuse de l'image US dans le cadre de la formation de voies. Les approches proposées détectent les réflecteurs forts du milieu sur la base de critères bayésiens. Nous avons finalement développé une nouvelle façon d'aborder la formation de voies en imagerie US, en la formulant comme un problème inverse linéaire liant les échos réfléchis au signal final. L'intérêt majeur de notre approche est la flexibilité dans le choix des hypothèses statistiques sur le signal avant la formation de voies et sa robustesse dans à un nombre réduit d'émissions. Finalement, nous présentons une nouvelle méthode de formation de voies pour l'imagerie US basée sur l'utilisation de caractéristique statistique des signaux supposée alpha-stable. / Ultrasound (US) allows non-invasive and ultra-high frame rate imaging procedures at reduced costs. Cardiac, abdominal, fetal, and breast imaging are some of the applications where it is extensively used as diagnostic tool. In a classical US scanning process, short acoustic pulses are transmitted through the region-of-interest of the human body. The backscattered echo signals are then beamformed for creating radiofrequency(RF) lines. Beamforming (BF) plays a key role in US image formation, influencing the resolution and the contrast of final image. The objective of this thesis is to model BF as an inverse problem, relating the raw channel data to the signals to be recovered. The proposed BF framework improves the contrast and the spatial resolution of the US images, compared with the existing BF methods. To begin with, we investigated the existing BF methods in medical US imaging. We briefly review the most common BF techniques, starting with the standard delay-and-sum BF method and emerging to the most known adaptive BF techniques, such as minimum variance BF. Afterwards, we investigated the use of sparse priors in creating original two-dimensional beamforming methods for ultrasound imaging. The proposed approaches detect the strong reflectors from the scanned medium based on the well-known Bayesian Information Criteria used in statistical modeling. Furthermore, we propose a new way of addressing the BF in US imaging, by formulating it as a linear inverse problem relating the reflected echoes to the signal to be recovered. Our approach offers flexibility in the choice of statistical assumptions on the signal to be beamformed and it is robust to a reduced number of pulse emissions. At the end of this research, we investigated the use of the non-Gaussianity properties of the RF signals in the BF process, by assuming alpha-stable statistics of US images.

abstract: Voicing, as it pertains to saxophone pedagogy, presents certain obstacles to both teachers and students simply because we cannot visually assess the internal mechanics of the vocal tract. The teacher is then left to instruct based on subjective “feel” which can lead to conflicting instruction, and in some cases, misinformation. In an effort to expand the understanding and pedagogical resources available, ten subjects—comprised of graduate-level and professional-level saxophonists—performed varied pitch bend tasks while their tongue motion was imaged ultrasonographically and recorded. Tongue range of motion was measured from midsagittal tongue contours extracted from the ultrasound data using a superimposed polar grid. The results indicate variations in how saxophonists shape their tongues in order to produce pitch bends from F6. / Dissertation/Thesis / Doctoral Dissertation Music 2016

Em formação de imagens por ultrassom de objetos com superfícies curvas, em imersão, se as velocidades de propagação no ruído e no objeto forem muito diferentes os efeitos de refração precisam ser compensados. Nesse caso a posição e a forma da superfície precisam ser conhecidas. Neste trabalho a superfície é detectada pelo mesmo array linear que captura os sinais para a formação de imagem.Dois métodos rápidos de detecção de superfície foram propostos, um baseado em técnicas de formação de imagem e outro que utiliza informações de tempo de percurso de ecos extraídas diretamente dos sinais de ultrassom.Os dois métodos foram comparados,e o método baseado em imagem apresentou uma maior tolerância a erros nos sinais, enquanto o método baseado em tempo de percurso mostrou-se mais rápido.Com a superfície detectada, a imagem foi formada por combinação de imagens por abertura sintética, que apresentou uma boa resolução. O uso conjunto dos métodos de detecção de superfície propostos e da formação de imagem resultou em uma taxa de imagens que permite ensaios interativos,com processamento em uma CPU de uso geral. / In ultrasound imaging ofobjects with curved surface, in immersion, the refraction eects must be compensated for if the propagation speed in the uid is very dierent from the speed in the object. In this case the surface position and shape must be known. In this work the surface is detected by the same linear array that captures the signals for the image formation. Two fast methods for surface detection were proposed,one is based on image formation techniques and another utilizes the echotime-of-ight information directly from the ultra\\sound signals.The two methods were compared,and the image-based method was more tolerant of signal errors, while the time-of-ight-based method was faster. After the surface detection, the image was formed by combination of synthetic aperture images,with a good resulting resolution. The utilization of the proposed surface detection methods together with the image formation resulted in an image rate that allows interactive testing, with processing on a general-purpose CPU.

Os equipamentos de imagens por ultrassom com varredura eletrônica usam transdutores que não se moldam à superfície a ser examinada, pois são rígidos. Há transdutores com curvaturas fixas para aplicações específicas. Em aplicações médicas, esse não é um problema na maioria dos casos, pois os tecidos do corpo humano tomam a forma da face do transdutor. Isso não ocorre quando há estruturas ósseas próximas às camadas externas de tecidos moles. Nas aplicações industriais as superfícies são sólidas e, portanto, não se ajustam à superfície do transdutor, sendo necessário uma camada variável de acoplamento acústico. A possibilidade de uso de um transdutor flexível exige que sua curvatura seja conhecida para o direcionamento correto do feixe acústico usado na formação de imagens. Assim sendo, um transdutor multielemento flexível apresentaria a vantagem de poder ser acoplado na superfície curva diretamente, tanto em aplicações médicas quanto industriais. Os transdutores flexíveis relatados na literatura científica não são compactos e dispõe de complicados sistemas de sensoriamento usados na determinação de curvaturas, além de demandar por sofisticados sistemas de aquisição e processamento dos sinais. Este trabalho propõe o desenvolvimento de transdutores multielementos flexíveis compactos para serem acoplados diretamente em superfícies curvas de peças mecânicas ou do corpo humano. Neste trabalho os sensores de curvatura responsáveis pela medição da curvatura foram desenvolvidos segundo os princípios básicos de extensômetria e resistência dos materiais para serem embebidos nas camadas do transdutor flexível de ultrassom. No desenvolvimento, foram fabricadas quatro versões de transdutores, com frequências de 1 e 2,25MHz. Todos os materiais usados na fabricação dos protótipos foram especificados segundo suas propriedades mecânicas e acústicas. Os protótipos fabricados foram caracterizados tendo sido medidas a largura de banda de cada elemento do transdutor, o comprimento e a duração dos pulsos, e uma medida da resolução axial. Para o protótipo de 2,25MHz, uma medida estimada da resolução lateral foi feita pela simulação do campo acústico, considerando o transdutor curvado em uma superfície cilíndrica. Para se testar o desempenho dos protótipos, foram realizados diferentes testes de formação de imagem. A versão de transdutor flexível de 1MHz e sem sensor de curvatura foi curvado sobre um cilindro e imerso em um tanque com água para a realização de testes de formação de imagem usado na detecção de objetos e obstáculos. Para as versões de transdutores médicos com sensor de curvatura, construiu-se duas versões de phantom simulando uma interface óssea cortical densa dentro de um tecido mole humano. O phantom usado para testar o protótipo de 2,25MHz foi concebido por uma amostra de tíbia bovina fraturada embebida dentro de um material com propriedades acústicas muito próximas a da água. Os testes de imagem foram realizados com o transdutor de 2,25MHz curvado sobre a superfície cilíndrica do phantom. As imagens de ultrassom das regiões fraturadas do osso foram detectadas, e uma comparação entre as técnicas de varredura setorial e STA usadas na obtenção das imagens foram feitas. Mostrou-se que é possível fabricar, de uma forma simples, transdutores multielementos flexíveis mais compactos e dotados de sensor de curvatura, e sem a necessidade de se usar tecnologias sofisticadas e caras ou de se valer de sistemas complexos de formação e processamento de sinais. As imagens obtidas pelos protótipos mostraram que os protótipos podem ser usados em diferentes aplicações NDT na indústria. Em especial, o protótipo de 2,25MHz mostrou ainda que tem potencial no uso médico para a obtenção de imagens de fraturas em contornos ósseos mais densos. / Ultrasound image equipment with electronic scanning considers that transducers cannot take the shape of the surface to be examined because they are rigid. There are transducers with fixed curvatures for specific applications. In medical applications, this is not a serious problem in most cases, since the face of the transducer can be coupled to the soft tissues of the body. This does not occur when there are bone structures close to the external layers of soft tissue. In industrial applications, the surfaces are solid and therefore do not fit to the transducer surface, where a variable layer of acoustic coupling is necessary. The possibility of using a flexible transducer requires its curvature to be known in order to the correct the direction of the acoustic beam which will be used in imaging applications. Thus, a flexible array transducer would have the advantage of being directly coupled to the curved surface in medical and in industrial applications. Flexible ultrasound transducers reported in the scientific literature are not compact, having complex sensing systems used to determine curvature; furthermore, they require sophisticated signal acquisition and processing systems. The development of flexible compact ultrasound linear array transducers to be coupled directly onto curved surfaces of mechanical parts as well of the human body is proposed here. The bend sensors responsible for measuring the curvature were developed according to the basic principles of strain gauge in extensometry and strength of materials to be embedded in the layers of the flexible ultrasound transducer. During this development, four versions of transducers were manufactured, with frequencies of 1 and 2.25MHz. All the materials used in the prototypes manufacturing were selected based on their mechanical and acoustic properties. The manufactured prototypes were characterized in terms of measured parameters, such as the bandwidth of each transducer element, the length and duration of the pulses, and a measure of axial resolution. For the 2.25MHz prototype, the value of the lateral resolution was estimated by simulating the acoustic field considering the transducer curved over a cylindrical surface. In order to test the transducer prototypes, different ultrasound imaging tests were conducted. The 1MHz flexible transducer version without curvature sensor was bent over a cylinder and immersed in a water tank for performing image formation tests used to detect objects and obstacles. For the medical transducers version with curvature sensor, two versions of phantoms were constructed simulating a dense cortical bone interface located inside the soft human tissue. The phantom applied to test the 2.25 MHz prototype consists of a fractured sample of bovine tibia which was embedded within a material having acoustic properties very close to that of the water. Ultrasound imaging tests were performed with the 2.25MHz transducer curved over the cylindrical surface of the phantom. The regions of the fractured bone were detected in the ultrasound images, and a comparison between the STA and sector scanning techniques used for obtaining the images was made. The study showed that it is possible to manufacture flexible and more compact array transducers provided with curvature sensor, without the need of using sophisticated and expensive technologies or taking advantage of complex formation and signal processing systems. The images obtained by the prototypes showed that they can be employed in different NDT applications in the industry. Particularly, the 2.25MHz prototype also showed its potential for medical imaging fractures in dense bone contours.

Suite à l’émergence de protocoles d’hypofractionnement à visée curative comportant un risque accru de toxicité, il devient fondamental d’arriver à augmenter la précision dans la délivrance de la dose. Les mouvements internes entre et pendant les séances d’irradiation peuvent devenir un facteur limitant majeur pour la qualité de l’irradiation des localisations tumorales mobiles. C’est le cas pour le cancer de la prostate pour lequel l’hypofractionnement est une voie prometteuse bien qu’il existe un risque élevé de toxicité digestive. Lors de cette thèse, nous nous sommes intéressés à la quantification et correction des mouvements du volume cible irradié dans le cadre d’une radiothérapie pour un cancer de la prostate sans ou après ablation totale de la glande. Nous avons étudié un nouveau système d’imagerie basé sur la modalité ultrasons (US) permettant de visualiser la zone pelvienne grâce à deux voies d’acquisition : transabdominale (TA) et transpérinéale (TP). Contrairement aux systèmes US précédemment commercialisés, les mouvements entre les séances de simulation et de traitement (mouvements interfractions) sont quantifiés par recalage monomodal US/US. De plus, des images acquises avec la sonde TP en continu pendant l’irradiation permettent de quantifier les mouvements intrafractions du volume cible. Nous avons proposé une méthodologie d’évaluation des deux sondes US-TA et US-TP pour la correction des mouvements interfractions, en conditions cliniques. Les données US ont été comparées à celles obtenues par tomodensitométrie (CBCT), actuelle modalité de référence. De plus, nous avons quantifié pour la première fois les incertitudes liées à l’impact de la pression de la sonde sur la localisation du volume cible, et à la variabilité inter-opérateur du recalage manuel US/US. Nous avons observé pour la sonde TA une faible concordance entre les mouvements interfractions mesurés par US et CBCT, ainsi qu’une variabilité importante de la pression exercée par la sonde et du recalage manuel entre les opérateurs. Pour la sonde TP, nous avons proposé une méthode corrective de la localisation de l’image US de référence qui nous a permis de valider son utilisation en clinique. Les données recueillies avec la sonde TP ont montré une importante variation des amplitudes et fréquences des mouvements intrafractions, parfois supérieurs à 15mm, entre les patients et d’une séance à l’autre pour un même patient. Nous avons proposé une étude dosimétrique des conséquences de ces déplacements et ainsi démontré que l’impact sur la dose délivrée au volume cible est patient-dépendant, et est plus important lorsque le traitement est délivré avec une stratégie d’hypofractionnement. Nous avons démontré dans cette étude la faisabilité de l'implémentation clinique de la technique US-TP qui permet un repositionnement quotidien en début de séance sans dose additionnelle ou marqueurs invasifs, et la correction de la position du volume cible pendant l’irradiation. / The emergence of hypofractionated treatments implies an increase of precision on the dose delivery. Organs motions between and during the irradiation fraction are a limiting factor for achieving a high quality treatment of mobile tumor localizations. In particular, hypofractionation was demonstrated as a promising strategy for prostate cancer treatment, whereas a high digestive toxicity cannot be excluded.During this thesis, motions of the target volume were quantified during radiotherapy delivered for treating a prostate cancer, on the prostatic gland or after a prostatectomy. An innovative imaging modality was used, based on two different ultrasound (US) probes: a transabdominal (TA) probe and a transperineal (TP) probe. Contrary to US systems previously commercialized, motions between simulation and treatment sessions were quantified with a monomodal registration US/US. Moreover, intrafraction motions of the target volume were recorded with the TP probe, since images can be continuously acquired with this probe. A methodology for evaluating the performances of the TA and TP probes were developed for the correction of interfractions motions, in clinical conditions. US data were compared with the current reference modality, the Cone Beam Computed Tomography (CBCT). Moreover, the uncertainties on the target localization due to the variability of the probe pressure and to inter-operator variability of the manual US/US registration were quantified for the first time. Poor agreements of the interfraction motions measurements were found between US and CBCT modalities, using the TA probe. Furthermore, a high variability of the TA probe pressure and of the inter-operator registration was observed. Using the TP probe, a corrective method of the US reference image localization was developed and validated, leading to a high agreement with the CBCT modality.Intrafraction motions were observed with the TP probe, and were highly patient and session dependent. A dosimetric study was proposed to evaluate the impact of the intrafraction motion on the dose delivery. The effects were patient dependent and more important when the treatment was simulated using a hypofractionated strategy.

Physiotherapist-supervised pelvic floor muscle (PFM) training is the recommended first-line treatment for women with stress urinary incontinence (SUI); however, only up to 50% of women are cured with this treatment. The primary objective of this study was to develop a predictive model of successful physiotherapy intervention outcomes among women with SUI using predictors that are accessible to clinicians. The secondary objective of this study was to run a preliminary investigation of morphologic differences between women with SUI who were cured with a physiotherapy intervention and those who were not cured, using a subset of ultrasound imaging data. Seventy-nine women with SUI were assessed at baseline on measures of demographic data (i.e. age, body mass index, etc.), 3-day bladder diary, 30-minute standardized pad test, clinical assessments of PFM strength and tone, and transperineal ultrasound assessments of PFM morphology. Women then attended a 12-week physiotherapy intervention and returned for a follow-up assessment. The multivariate logistic regression model was significant (p < .001) with two predictors: baseline ICIQ-FLUTS UI subscale (SUI severity; p = .01) and parity (p = .06). A significant ROC curve for the ICIQ-FLUTS UI subscale (p ˂ .01) predicts physiotherapy intervention outcomes with 55.6% sensitivity and 80.8% specificity at a cut-off score of 7.50. Women most likely to be cured with a physiotherapy intervention were those with lower scores on the ICIQ-FLUTS UI subscale and those who have given birth to fewer children. Significant differences were found in a subset of data between women with SUI who are cured with the physiotherapy intervention and women who are not cured on morphologic measures in standing of bladder neck height at peak cough (p = .03), descent of the bladder neck during maximal Valsalva maneuver (MVM; p = .04), levator hiatus circumference at rest (p = .03) and at maximal voluntary contraction in both standing and supine (MVC; p = .01; p = .03). Variables that were trending towards significance included bladder neck height in standing at rest, levator plate length (LPL) at maximal excursion during a cough and MVM in standing, and mid-urethral wall cross-sectional area. These significant differences indicate potential value in using ultrasound imaging outcomes as predictors of a cure with physiotherapy intervention in future models, and a combination of demographic, clinical, and morphologic variables may build a more robust predictive model.

The mobility and biomedical applications of a microscale magnetic tumbling (μTUM) robot capable of traversing complex terrains in dry and wet environments is explored. Roughly 800 x 400 x 100 μm in size, the robot is fabricated using standard photolithography techniques and consists of a rectangular polymeric body with embedded NdFeB particles. Static force analysis and dynamic modeling of its motion characteristics are performed with experimental verification. Techniques for simulating the intermittent, non-contact behavior of tumbling locomotion are used to find an optimized design for the microrobot, reducing time and resources spent on physical fabrication. When subject to a magnetic field as low as 3 mT, the microrobot is able to translate at speeds of over 30 body lengths/s (24 mm/s) in dry conditions and up to 8 body lengths/s (6.8 mm/s) in wet conditions. It can climb inclined planes up to 60° in wet conditions and up to 45° in dry conditions. Maximum open loop straight-line trajectory errors of less than 4% and 2% of the traversal distance in the vertical and horizontal directions, respectively, were also observed. Full two-dimensional directional control of the microrobot was shown through the traversal of a P-shaped trajectory. The microrobot's real-time position can be accurately tracked through visual occlusions using ultrasound imaging. When applied as a coating, a fluorescein payload was found to diffuse over a two hour time period from the microrobot. Cytotoxicity tests also demonstrated that the microrobot's SU-8 body is biocompatible with murine fibroblasts. The microrobot's capabilities make it promising for targeted drug delivery and other in vivo biomedical applications.