Dissertations / Theses on the topic 'Biomedical imaging'
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1
Luo, Yuan. "Novel Biomedical Imaging Systems." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/193907.
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The overall purpose of the dissertation is to design and develop novel optical imaging systems that require minimal or no mechanical scanning to reduce the acquisition time for extracting image data from biological tissue samples. Two imaging modalities have been focused upon: a parallel optical coherence tomography (POCT) system and a volume holographic imaging system (VHIS). Optical coherence tomography (OCT) is a coherent imaging technique, which shows great promise in biomedical applications. A POCT system is a novel technology that replaces mechanically transverse scanning in the lateral direction with electronic scanning. This will reduce the time required to acquire image data. In this system an array with multiple reduced diameter (15μm) single mode fibers (SMFs) is required to obtain an image in the transverse direction. Each fiber in the array is configured in an interferometer and is used to image one pixel in the transverse direction. A VHIS is based on volume holographic gratings acting as Bragg filters in conjunction with conventional optical imaging components to form a spatial-spectral imaging system. The high angular selectivity of the VHIS can be used to obtain two-dimensional image information from objects without the need for mechanical scanning. In addition, the high wavelength selectivity of the VHIS can provide spectral information of a specific area of the object that is being observed. Multiple sections of the object are projected using multiplexed holographic gratings in the same volume of the Phenanthrenquinone- (PQ-) doped Poly (methyl methacrylate) (PMMA) recording material.
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Cole, Mary Janet. "Fluorescence lifetime imaging for biomedical applications." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393718.
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Meah, Christopher James. "Developing plenoptic technology for biomedical imaging." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7697/.
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Plenoptic imaging is an exciting research field since, by introducing a microlens array into the optical train of a traditional camera, directional information about incoming light rays is stored on the sensor. Whereas traditional cameras discard this information, plenoptic imaging takes advantage of this increase in angular resolution to provide a method of snapshot 3D capture. With a plenoptic dataset, the ability to extend depth of field and refocus digitally, post-acquisition, is of key benefit to bioluminescence tomography. Due to low light imaging conditions, large apertures are required to capture enough signal from a bioluminescence imaging subject; this causes a shallow depth of field, and when mirrors are introduced into the system to increase subject coverage, managing the system focal planes can be hard. In order to investigate the best uses of plenoptic imaging for biomedical research, a simulation platform was created to allow efficient, flexible, cost effective exploration of system design and algorithm development. This simulation platform was utilised in designing a plenoptic multi-view system, which is applicable to bioluminescence tomography. A correction to the bioluminescence free space model is made which facilitates quantitative imaging. Finally, a plenoptic tomography system is created which allows snapshot, multi-view 3D capture.
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Percival, Sarah Jane. "Functionalised silica nanoparticles for biomedical imaging." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/44837.
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Magnetic resonance imaging is one of the most widely used diagnostic techniques in the clinic as it affords many of the attributes sought from a non-invasive imaging modality. The main limitation of MRI is its inherent insensitivity, and as a result only large-scale abnormalities can be detected from a scan. With an increasing demand for earlier cancer diagnosis there has been a move towards imaging the molecular biomarkers that are present from the beginning of the disease process. This thesis describes the development of highly fluorinated, silica nanoparticles to actively target cancer cells for imaging by 19F MRI. Silica nanoparticles were prepared, and their size optimised for the molecular imaging application. A method was developed to modify the nanoparticles with the highest possible number of surface amine groups. These amine groups were conjugated to fluorinated PEG chains, each containing six equivalent 19F nuclei, and the resulting particles had a high 19F content. To provide the particles with the properties required for a molecular imaging probe, a tenth of the surface bound 19F PEG chains were conjugated to targeting peptides and the remainder were coupled to stabilising ligands. Using quantitative characterisation techniques each modification step was optimised and the exact composition of the nanoparticles was determined. To complement 19F MRI, fluorophores were incorporated into the particles for optical detection as this modality offered an accessible, sensitive and inexpensive alternative. Several samples were prepared which incorporated fluorophores at different positions throughout the nanoparticle structure. Adding the fluorophores to the nanoparticle surface was found to produce the most sensitive optical probe. The final particles were used for in vitro targeting studies to assess their potential as molecular imaging probes. Preliminary in vitro assays demonstrated that these particles selectively targeted cancer cells in the M21 cell line when compared to a control.
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Steuwe, Christian. "Nonlinear photonics in biomedical imaging and plasmonics." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708016.
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Amor, Rumelo. "Nonlinear and interference techniques for biomedical imaging." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24918.
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Optical microscopy has long been an established tool in the biomedical sciences, being the preferred choice in the study of single cells and tissue sections. The realisation of the confocal laser scanning microscope in the 1980s led to major advances in the way optical microscopy is implemented, paving the way for the use of interference techniques such as 4Pi microscopy to increase the optical resolution, and for nonlinear microscopy techniques such as two-photon microscopy, which allows deeper penetration and the imaging of live specimens as a consequence of reduced photo-bleaching, and coherent anti-Stokes Raman scattering (CARS) microscopy, which produces high-contrast images without the need for fluorescent staining. In this work, I discuss advances in nonlinear and interference techniques available for biomedical imaging. I present a simultaneous near-field and far-field viewer for use in aligning the input beams in a CARS microscope and in a sum-frequency-generation- based two-photon microscope. I show 3D optical sectioning of whole mouse embryos using the Mesolens, a giant microscope objective capable of subcellular resolution in a 5 mm field of view, and present theoretical calculations on its use for two-photon microscopy. I present fast recording of synaptic events in neurones, with reduced photo-bleaching, using widefield two-photon microscopy. Finally, I show multiple super-resolved sections are obtained using a laser scanning standing wave microscope, generating precise contour maps of the surface membrane of red blood cells and revealing 3D information from a single image.
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Fairbairn, Natasha. "Imaging of plasmonic nanoparticles for biomedical applications." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/353976/.
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Plasmonic nanoparticles show potential for numerous different biomedical applications, including diagnostic applications such as targeted labelling and therapeutic applications such as drug delivery and therapeutic hyperthermia. In order to support the development of these applications, imaging techniques are required for imaging and characterising nanoparticles both in isolation and in the cellular environment. The work presented in this thesis relates to the use and development of two different optical techniques for imaging and measuring the localised surface plasmon resonance of plasmonic nanoparticles, both for isolated particles and for particles in a cellular environment. The two techniques that have been used in this project are hyperspectral darkfield microscopy and spatial modulation microscopy. Hyperspectral darkfield microscopy is a darkfield technique in which a supercontinuum light source and an acousto-optic tuneable filter are used to collect darkfield images which include spectral information. This technique has been used to measure the spectra of single nanoparticles of different shapes and sizes, and nanoparticle clusters. The results of some of these measurements have also been correlated with finite element method simulations and transmission electron microscope images. The hyperspectral darkfield technique has also been used to image cells that have been incubated with nanoparticles, demonstrating that this technique may also be used to measure the spectra of nanoparticle clusters on a cellular background. Spatial modulation microscopy is based on fast modulation of the position of a nanoparticle in the focus of an optical beam. This modulation results in a variation in transmitted intensity, which can be detected with very high sensitivity using a lock-in amplifier. Since, for biological imaging applications it is desirable to be able to image, for example whole cells in real time, a fast scanning version of this technique has been implemented, which increases the applicability of the technique to imaging of nanoparticles in cells
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SARWAR, IMRAN. "Microwave Imaging Specialized Hardware for Biomedical Applications." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2734429.
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Cai, Hongmin. "Quality enhancement and segmentation for biomedical images." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39380130.
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Cai, Hongmin, and 蔡宏民. "Quality enhancement and segmentation for biomedical images." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39380130.
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Liu, Yehe. "System and Process Optimization for Biomedical Optical Imaging." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case162556700760192.
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Huang, Jiwei. "Multispectral Imaging of Skin Oxygenation." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1356637098.
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McPheeters, Matthew Thomas. "Imaging Corneal Nerve Activity." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1626615737894263.
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Pérez, Rosas Juan Miguel. "Imaging cytometry technology for environmental and biomedical applications." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669608.
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Early detection of microorganisms in environmental and biomedical applications is critical for the effective response to potential pathogenic treats. Most traditional methods and instrumentation for the analysis of these samples are becoming obsolete due to the fact that they are time-consuming and have long response times. Modern solutions are limited to high-end centralized facilities and specialized trained personnel, given their high-cost and complexity. There is thus a clear need to develop and introduce low-cost, easy to use, high-performance devices capable of rapidly identifying and quantifying pathogenic microorganisms in environmental and biomedical samples.
The work behind this thesis was devoted to the design, development and validation in relevant industrial environments of two image cytometry devices capable of characterizing biological and industrial samples in terms of their microorganism content. Bringing a potentially high-impact solution to the current industry need.
The first technology, defined within the context of this thesis as Fourier image cytometry, is an optical device capable of increasing the sample volume tested when compared to traditional state-of-the-art counterparts. By evaluating the sample in the Fourier domain, the device is capable of measuring characteristics of particulate within a sample volume larger than other imaging systems. The result is an enhancement of both field of view (FOV) and depth of field (DOF) of the target sample. Furthermore, the implementation of the Fourier image cytometer in this thesis is a portable and compact device comprising of low-cost optics and electronics. The design of the entire device was performed with the objective to minimize the cost and maximize the capabilities. This was possible mainly due to the recent advances in image sensor technologies that simplify the device’s optics. In our Fourier imaging cytometry, LED light sources and conventional achromatic optical lenses are at the basis of device’s optics as opposed to high-end lasers or optical microscopes. For the detection scheme, a CMOS image sensor was used.
After optimizing the prototype and going through rigorous validation in a laboratory, the Fourier image cytometry introduced in this thesis was validated in two relevant industrial environments. The device was tested using real environmental samples. In the first industrial validation, it was used for the microorganism’s identification and quantification in water coming from cooling towers. The second industrial validation used a further optimized implementation of the cytometer to analyze fresh and marine waters for their microorganism population, specifically phytoplankton within the context of ballast water and ballast water treatment systems.
The second image cytometry designed, developed and implemented within the scope of this thesis, focused on detection of microorganisms spread over surfaces. Following the motivation for low-cost compact devices, a Surface cytometer was designed. The Surface cytometer is an optical device capable of quantifying bacterial population over a surface of over 300 mm2. The device was completely autonomous thanks to the integration of a single-board computer within its design. The light source and detection scheme continued to be LED source and CMOS sensor detection. Similarly to the validation process of the Fourier cytometer, the Surface cytometer was tested in controlled samples in a laboratory environment, before it was put to test on a biomedical application for bacterial growth monitoring and compared to standard devices of measurement of optical density, used today in the industry.
In summary, in this thesis we present two novel image cytometers and three clear industrial applications in which the devices were validated. This clearly indicates the potential of image cytometry as an effective low cost and portable tool for the analysis of microorganisms in the environmental and biomedical sectorLa detección temprana de microorganismos en aplicaciones ambientales y biomédicas es crítica para la respuesta efectiva a posibles amenazas patogénicas. La mayoría de los métodos e instrumentos tradicionales para este tipo de análisis están casi obsoletas, debido a los esfuerzos que requieren y sus largos tiempos de respuesta. Las soluciones modernas se limitan a instalaciones centralizadas de alta gama y personal especializado, esto debido a su alto coste y complejidad. Existe una clara necesidad de desarrollar e introducir dispositivos de bajo costo, fáciles de usar y de alto rendimiento capaces de identificar y cuantificar rápidamente microorganismos patogénicos en muestras ambientales y biomédicas. El trabajo detrás de esta tesis se dedicó al diseño, desarrollo y validación en entornos industriales relevantes de dos dispositivos de citometría de imagen. La primera tecnología, definida como citometría de imagen de Fourier, es un dispositivo óptico capaz de aumentar el volumen de muestra capturado en comparación con las tecnologías tradicionales y el estado del arte. Al evaluar la muestra en el dominio de Fourier, el sistema es capaz de medir las características de las partículas dentro de un volumen de muestra mayor que los sistemas de imágenes comparativos. El sistema resultante mejora tanto el campo de visión (FOV, por sus siglas en inglés) como la profundidad de campo (DOF, por sus siglas en inglés) de la muestra. Además, la implementación del citómetro de imagen de Fourier en esta tesis es un dispositivo compacto y portátil compuesto por componentes ópticos y electrónicos de bajo coste. El diseño de todo el sistema se realizó con el objetivo de minimizar el coste del sistema y maximizar sus prestaciones. Esto fue posible principalmente debido a los recientes avances en las tecnologías de sensores de imagen que nos permitieron simplificar la óptica del dispositivo. En esta implementación de la citometría de imagen de Fourier, fuentes de luz LED y las lentes ópticas acromáticas convencionales comprenden la óptica del sistema en lugar de láseres de alta gama u objetivos de microscopios ópticos. Para el esquema de detección se utilizó un sensor de imagen CMOS. La citometría de imagen de Fourier presentada en esta tesis también fue validada en dos entornos industriales relevantes. El sistema se probó utilizando muestras ambientales reales. En la primera validación industrial, el sistema se utilizó para la identificación y cuantificación del microorganismo en el agua proveniente de torres de refrigeración. En la segunda validación industrial se analizaron aguas dulces y marinas, y su población de microorganismos, específicamente la cuantificación de phytoplankton en el contexto de sistemas de tratamiento de aguas de lastre. La segunda citometría de imagen diseñada, desarrollada e implementada dentro del alcance de esta tesis se centró en la detección de microorganismos sobre superficies. Siguiendo la motivación de los dispositivos compactos de bajo costo, se diseñó un citómetro de superficie. El citómetro de superficie es un dispositivo óptico capaz de cuantificar la población bacteriana en una superficie de más de 300 mm2. El dispositivo es completamente autónomo gracias a la integración de una computadora de placa única dentro de su diseño. La fuente de luz y el esquema de detección continuaron siendo LED y sensor CMOS. De manera similar al proceso de validación del citómetro de Fourier, el citómetro de superficie se probó en muestras controladas en un entorno de laboratorio, antes de someterse a prueba en una aplicación biomédica para el monitoreo del crecimiento bacteriano y se comparó con los sistemas estándar de medición de densidad óptica, utilizados hoy en día. en la industria. En resumen, en esta tesis presentamos dos nuevas tecnologías de citometría, junto con dos dispositivos de alto rendimiento y tres aplicaciones industriales
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Tayyab, Muhammad. "Segmentation and Contrasting in Different Biomedical Imaging Applications." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00747430.
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Advancement in Image Acquisition Equipment and progress in Image Processing Methods have brought the mathematicians and computer scientists into areas which are of huge importance for physicians and biologists. Early diagnosis of diseases like blindness, cancer and digestive problems have been areas of interest in medicine. Development of Laser Photon Microscopy and other advanced equipment already provides a good idea of very interesting characteristics of the object being viewed. Still certain images are not suitable to extract sufficient information out of that image. Image Processing methods have been providing good support to provide useful information about the objects of interest in these biological images. Fast computational methods allow complete analysis, in a very short time, of a series of images, providing a reasonably good idea about the desired characteristics. The thesis covers application of these methods in 3 series of images intended for 3 different types of diagnosis or inference. Firstly, Images of RP-mutated retina were treated for detection of rods, where there were no cones present. The software was able to detect and count the number of cones in each frame. Secondly, a gastrulation process in drosophila was studied to observe any mitosis and results were consistent with recent research. Finally, another series of images were treated where biological cells were observed to undergo mitosis. The source was a video from a photon laser microscope. In this video, objects of interest were biological cells. The idea was to track the cells if they undergo mitosis. Cell position, spacing and sometimes contour of the cell membrane are broadly the factors limiting the accuracy in this video. Appropriate method of image enhancement and segmentation were chosen to develop a computational method to observe this mitosis. Cases where human intervention may be required have been proposed to eliminate any false inference.
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Amrania, Hemmel. "Ultrafast Mid-Infrared Spectroscopic Imaging with Biomedical Applications." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526408.
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Jin, Jiefu, and 金介夫. "Functional lanthanide-based nanoprobes for biomedical imaging applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47752579.
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Lanthanide-doped upconversion nanoparticles (UCNPs) are perceived as promising
novel near-infrared (NIR) bioimaging agents characterised by high contrast and high
penetration depth. However, the interactions between charged UCNPs and
mammalian cells have not been thoroughly studied and the corresponding
intracellular uptake pathways remain unclear.
Herein, my research work involved the use of hydrothermal method and ligand
exchange approach to prepare UCNP-PVP, UCNP-PEI, and UCNP-PAA. These
polymer-coated UCNPs demonstrated good water dispersibility, the similar size
distribution as well as similar upconversion luminescence efficiency. However, the
positively charged UCNP-PEI evinced greatly enhanced cellular uptake in
comparison with its neutral or negative counterparts, as revealed by cellular uptake
studies. Meanwhile, it was discovered that cationic UCNP-PEI could be effectively
internalized mainly through the clathrin endocytic machanism. This study is the first
report on the endocytic mechanism of positively charged lanthanide-doped UCNPs.
Furthermore, it allows us to control the UCNP-cell interactions by tuning surface
properties.
Glioblastoma multiforme (GBM) is the most common and malignant form of primary
brain tumors in humans. Small molecule MRI contrast agents are used for GBM
diagnosis and preoperative tumor margin delineation. However, the conventional
gadolinium-based contrast agents have several disadvantages, such as a relatively low
T1 relaxivity, short circulation half lives and the absence of tumor targeting efficiency.
Multimodality imaging probes provide a better solution to clearly delineate the
localization of glioblastoma.
My research work also involved the development of multimodal nanoprobes for
targeted glioblastoma imaging. Two targeted paramagnetic/fluorescence nanoprobes
were designed and synthesized, UCNP-Gd-RGD and AuNP-Dy680-Gd-RGD.
UCNP-Gd-RGD was prepared through PEGylation, Gd3+DOTA conjugation and
RGD labeling of PEI-coated UCNP-based nanoprobe core (UCNP-NH2). It adopted
the cubic NaYF4 phase, had an average size of 36 nm by TEM, and possessed a
relatively intense upconversion luminescence of Er3+ and Tm3+. It also exhibited
improved colloidal stability and reduced cytotoxicity compared with UCNP-NH2, and
a higher T1 relaxivity than Gd3+DOTA. AuNP-Dy680-Gd-RGD was synthesized
through bioconjugation of amine-modified AuNP-based nanoprobe core (AuNPPEG-
NH2) by a NIR dye (Dy680), Gd3+DOTA and RGD peptide. It demonstrated a
size of 3–6 nm by TEM, relatively strong NIR fluorescence centered at 708 nm, longterm
physiological stability, and an enhanced T1 relaxivity compared with
Gd3+DOTA.
Targeting abilities of both UCNP-Gd-RGD and AuNP-Dy680-Gd-RGD towards
overexpressed integrin αvβ3 receptors on U87MG cell surface was confirmed by their
enhanced cellular uptake visualized by confocal microscopy imaging and quantified
by ICP-MS, where their corresponding control nanoprobes were used for comparison.
Furthermore, targeted imaging capabilities of UCNP-Gd-RGD and AuNP-Dy680-Gd-
RGD towards subcutaneous U87MG tumors were verified by in vivo and ex vivo
upconversion fluorescence imaging studies and by in vivo and ex vivo NIR
fluorescence imaging and in vivo MR imaging studies, respectively. These two
synthesized targeted nanoprobes, with surface-bounded cyclic RGD peptide and
numerous T1 contrast enhancing molecules, are applicable in targeted MR imaging
glioblastoma and delineating the tumor boundary. In addition, UCNP-Gd-RGD
favors the upconversion luminescence with NIR-to-visible nature, while AuNPDy680-
Gd-RGD possesses NIR-to-NIR fluorescence, and both lead to their potential
applications in fluorescence-guided surgical resection of gliomas.published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
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Wang, Fangjing. "Biomedical Imaging of Stem Cells Using Reporter Genes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1261441999.
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Yeo, Woon Gi. "Terahertz Spectroscopic Characterization and Imaging for Biomedical Applications." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1430825935.
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Sandiford, Lydia Grace. "Development of novel nanomaterials for multimodal biomedical imaging." Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/development-of-novel-nanomaterials-for-multimodal-biomedical-imaging(e0472af1-2c89-4b64-81b8-1bfbbfc12429).html.
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This thesis focuses on the development of novel nanomaterials for biomedical imaging using both iron oxide nanoparticles and cadmium based quantum dots, and two different coating methods. The first approach involved a coating ligand consisting of the stealth molecule polyethylene glycol, and a bisphosphonate enabling strong binding to the nanoparticle surface. This polymer conjugate was chosen in order to reduce undesirable reticuloendothelial system uptake, and hence increase blood circulation times allowing for efficient delivery of particles to specific in vivo vascular targets. The second route employed a naturally occurring amphiphilic protein, hydrophobin, as an encapsulation agent according water solubility of nanomaterials and potential for bioconjugation. The first part of the study involved the synthesis of novel iron oxide nanomaterials of small size distribution and a near-zero surface charge resulting in dispersions that were stable in solution for several months. Both longitudinal (r 1) and transverse (r 2) relaxivity measurements were performed at a clinically relevant magnetic field of 3 T, revealing a low r 2/r 1 ratio of 2.97 showing the particles to have optimal properties for efficient T1-weighted magnetic resonance imaging. The strong T1 effect was validated in vivo, revealing a long blood circulation time and a 6-fold enhancement of its signal, allowing for high resolution visualisation of vessels and vascularised organs. The low reticuloendothelial system uptake observed was confirmed by radiolabelling the particles, hence according dual-modality contrast, and performing in vivo single photon emission computed tomography. From this study, the blood half-life was calculated to be 2.97 h. In vitro targeting studies using three different cardiovascular/cancer biomarkers (VCAM-1, PSMA, and p32) were conducted, showing specific uptake of the targeted particles to relevant cell lines. The second section examines the potential for applying the polyethylene glycol-bisphosphonate coating to other inorganic nanomaterials. CdZnSeS alloyed quantum dots were successfully synthesised, with the resulting particles exhibiting red emission (_604.0 nm) and no significant shift after phase transfer into aqueous solution. Preliminary in vitro cell studies revealed particle emission at the expected wavelength. Finally, the synthesised nanoparticles were successfully coated with the amphiphilic protein (hydrophobin). The resulting nanoparticles exhibited no change in core size or morphology as determined by transmission electron microscopy, as well as no shift in emission (~627.0nm). In vitro studies were performed allowing for visualisation of the quantum dots in a biological environment after incubation at physiological temperature. In addition, particles were injected intratumourly into a live mouse model, with emission detected up to 24 h post injection. Lastly, radiolabelling with iodine-131 was achieved; confirming the possibility of utilising exposed residues on the protein to further functionalise the surface. In conclusion, the described methods and nanoparticles synthesised represent a promising platform for the development of targeted agents for multimodal medical imaging and other bio-applications.
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Koh, Kevin Rongsheng. "Multimodal multispectral optical endoscopic imaging for biomedical applications." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/6330.
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Optical imaging is an emerging field of clinical diagnostics that can address the growing medical need for early cancer detection and diagnosis. Various human cancers are amenable to better prognosis and patient survival if found and treated during early disease onset. Besides providing wide-field, macroscopic diagnostic information similar to existing clinical imaging techniques, optical imaging modalities have the added advantage of microscopic, high resolution cellular-level imaging from in vivo tissues in real time. This comprehensive imaging approach to cancer detection and the possibility of performing an ‘optical biopsy’ without tissue removal has led to growing interest in the field with numerous techniques under investigation. Three optical techniques are discussed in this thesis, namely multispectral fluorescence imaging (MFI), hyperspectral reflectance imaging (HRI) and fluorescence confocal endomicroscopy (FCE). MFI and HRI are novel endoscopic imaging-based extensions of single point detection techniques, such as laser induced fluorescence spectroscopy and diffuse reflectance spectroscopy. This results in the acquisition of spectral data in an intuitive imaging format that allows for quantitative evaluation of tissue disease states. We demonstrate MFI and HRI on fluorophores, tissue phantoms and ex vivo tissues and present the results as an RGB colour image for more intuitive assessment. This follows dimensionality reduction of the acquired spectral data with a fixed-reference isomap diagnostic algorithm to extract only the most meaningful data parameters. FCE is a probe-based point imaging technique offering confocal detection in vivo with almost histology-grade images. We perform FCE imaging on chemotherapy-treated in vitro human ovarian cancer cells, ex vivo human cancer tissues and photosensitiser-treated in vivo murine tumours to show the enhanced detection capabilities of the technique. Finally, the three modalities are applied in combination to demonstrate an optical viewfinder approach as a possible minimally-invasive imaging method for early cancer detection and diagnosis.
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Sharkey-Toppen, Travis P. "Imaging Iron and Atherosclerosis by Magnetic Resonance Imaging." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429796182.
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Shen, Litao. "Diffusion tensor imaging application." Thesis, Purdue University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1602902.
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Central nervous system (CNS) related conditions and diseases like mild traumatic brain injury (mTBI) and multiple sclerosis (MS) affect people’s life quality, yet there is no single test for the diagnosis of these diseases or conditions. Patients may need to wait for years until they are diagnosed correctly to get the correct treatment, which is often too late. Thus, there is a strong need to develop some techniques to aid the diagnosis of CNS-related conditions and diseases. The conventional MRI can reveal the structure of the brain but cannot detect the difference between the healthy tissue and the anomalies. Diffusion tensor imaging (DTI) has been used for detecting white matter integrity and demyelination for the past decade in experiments and has been proven to have the ability to depict the problem effectively. In the past decade, many techniques were found based on DTI data, and these techniques improved pre-processing, processing, and post-processing.
Though there are many software and APIs that can provide functions for DTI file input/output (IO), visualization and other DTI related topics, there is no general software or API that is dedicated to covering the whole processing procedure of DTI that at the same time can be extended easily by the user. This thesis is dedicated to developing a software that can be used to aid in the diagnosis of CNS-related conditions and diseases while at the same time trying to cover as many topics as possible. Another purpose is to make the software highly extensible.
This thesis work first introduces the background of CNS-related disease and uses MS as an example to introduce the process of demyelination and the white matter integrity problem, which are involved in these CNS-related diseases and conditions. Then the diffusion process and the technique that can detect the diffusion signal (DTI) is presented. After this, concepts and meaning of the secondary metrics are discussed. Then, current existing software and APIs and their advantages and disadvantages are outlined. After these points, the techniques that are discussed in this thesis as well as their advantages are outlined. This part is followed by the charts and code samples which can illustrate the process and structure of this software. Then different modules and their results are explained.
In this software, the results are represented by images and 3D models. There are color images, pseudo color images with different schemes and gray scale images. Images are mainly included to represent the FA and MD data. In this software, streamlines are generated from the eigenvalue and eigenvector. Then a bundled result for the streamline is also realized in this software. The streamline and bundled results are 3D models. For 3D models, there are mainly two ways to display the real 3D model. One is the naked eye 3D which doesn’t require the user to wear glasses but has less stereoscopic characteristics. As the stereoscopic monitors and glasses are more and more popular and easily accessible, this software also provides stereoscopic views for 3D models, and the user can choose red & blue, interlaced techniques with proper glasses.
This thesis work ends with the discussion of the results and limitations of DTI. Finally, there is a discussion about the future work that can improve the performance of this software and topics that need to be covered.
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Levesque, Ives. "Magnetization transfer imaging of multiple sclerosis." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79030.
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Magnetization transfer (MT) imaging is a magnetic resonance imaging techniqu ewhich permits indirect observation of the macromolecular component of biological tissue. Semi-quantitative implementations such as magnetization transfer ratio (MTR) imaging are very useful in the study of neuro-degenerative diseases, despite the relatively limited information provided by such single measurement methods. Quantitative techniques provide estimated measures of model parameters that more accurately describe the MT process. This thesis presents the application of quantitative MT imaging in a cross-sectional study of multiple sclerosis (MS) patients and healthy controls, exploring the on-going changes that occur in MS. Quantitative results are investigated to determine which model parameters play a role in the MTR. The findings demonstrate regional variations in white matter structures, and significant differences between healthy and normal-appearing MS tissue. The results also indicate the dominant role of macromolecular content in MTR, and confirm the destructive nature of T 1-hypointense lesions.
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Olarte, Omar E. "Development of novel imaging tools for selected biomedical applications." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/144559.
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In the quest for better and faster images of cellular and subcellular structures, biology-oriented optical microscopes have advanced significantly in the last few decades. Novel microscopy techniques such as non-linear microscopy (NLM), including two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) microscopy, and light-sheet fluorescence microscopy (LSFM) are emerging as alternatives that overcome some the intrinsic limitations of standard microscopy systems. In this thesis I aimed to advance such techniques even more, and combine them with other photonic technologies to provide novel tools that would help to address complex biological questions. This thesis is organized in two main parts. The first part is dedicated to applications involving femtosecond lasers that are employed for precise microsurgery. For that, damage assessment methodologies based on NLM were developed and tested in relevant biomedical models. In the second part, wavefront engineering methods were employed to enhance the imaging capabilities of light-sheet microscopy systems. These novel methodologies were tested as well in relevant biological applications.
This thesis is, therefore, organized as follows:
In chapter 1, a brief and comprehensive review of the basic microscopy techniques employed in this thesis is presented, together with the challenges and achievements of this thesis in sequential order.
In chapter 2, a multimodal imaging methodology for the assessment of laser induced collateral damage is presented. This was specifically developed for the control of the damage in femtosecond-laser dissection of single axons within a living Caenorhabditis elegans (C. elegans). Here, it is shown that collateral damages at the level of the myosin structure of the muscles adjacent to the axon, can be readily detected.
In chapter 3, the optimized multimodal methodology developed in the chapter 2 was employed for minimally invasive dissection of axons of D-type motoneurons in C elegans. Here, a microfluidic chip for C elegans immobilization and a detailed protocol was employed to evaluate the axon regeneration of such neurons. The potential of such platform for testing drugs with regeneration-enhancing capabilities is also presented.
In chapter 4, a novel use of TPEF microscopy is presented to characterize and fine tune the laser for photodisruption of excised human crystalline lens samples.
In chapter 5, a thorough description of the implementation of a multimodal Digital Scanned Light-Sheet Microscope (DSLM) able to work in the linear and nonlinear regimes under either Gaussian or Bessel beam excitation schemes, is presented. The enhanced capabilities of the developed system is evaluated using in vivo C. elegans samples and multicellular tumor spheroids
In chapter 6, the development of a completely new concept in light sheet-based imaging is presented. This is based on the extension of the depth-of-field of the lens in the emission path of the microscope by using wavefront coding (WFC) techniques. Furthermore, I demonstrate the application of the developed methodology for fast volumetric imaging of living biological specimens and 3D particle tracking.
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Oswald, Annahita. "Coping with new Challenges in Clustering and Biomedical Imaging." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-134971.
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Henriksson, Tommy. "CONTRIBUTION TO QUANTITATIVE MICROWAVE IMAGING TECHNIQUES FOR BIOMEDICAL APPLICATIONS." Doctoral thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-5882.
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This dissertation presents a contribution to quantitative microwave imaging for breast tumor detection. The study made in the frame of a joint supervision Ph.D. thesis between University Paris-SUD 11 (France) and Mälardalen University (Sweden), has been conducted through two experimental microwave imaging setups, the existing 2.45 GHz planar camera (France) and the multi-frequency flexible robotic system, (Sweden), under development. In this context a 2D scalar flexible numerical tool based on a Newton-Kantorovich (NK) scheme, has been developed. Quantitative microwave imaging is a three dimensional vectorial nonlinear inverse scattering problem, where the complex permittivity of an object is reconstructed from the measured scattered field, produced by the object. The NK scheme is used in order to deal with the nonlinearity and the ill-posed nature of this problem. A TM polarization and a two dimensional medium configuration have been considered in order to avoid its vectorial aspect. The solution is found iteratively by minimizing the square norm of the error with respect to the scattered field data. Consequently, the convergence of such iterative process requires, at least two conditions. First, an efficient calibration of the experimental system has to be associated to the minimization of model errors. Second, the mean square difference of the scattered field introduced by the presence of the tumor has to be large enough, according to the sensitivity of the imaging system. The existing planar camera associated to a flexible 2D scalar NK code, are considered as an experimental platform for quantitative breast imaging. A preliminary numerical study shows that the multi-view planar system is quite efficient for realistic breast tumor phantoms, according to its characteristics (frequency, planar geometry and water as a coupling medium), as long as realistic noisy data are considered. Furthermore, a multi-incidence planar system, more appropriate in term of antenna-array arrangement, is proposed and its concept is numerically validated. On the other hand, an experimental work which includes a new fluid-mixture for the realization of a narrow band cylindrical breast phantom, a deep investigation in the calibration process and model error minimization, is presented. This conducts to the first quantitative reconstruction of a realistic breast phantom by using multi-view data from the planar camera. Next, both the qualitative and quantitative reconstruction of 3D inclusions into the cylindrical breast phantom, by using data from all the retina, are shown and discussed. Finally, the extended work towards the flexible robotic system is presented.A dissertation prepared through an international convention for a joint supervision thesis with Université Paris-SUD 11, France
Microwaves in biomedicine
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Butzer, Jochen Sieghard. "MARS-CT: Biomedical Spectral X-ray Imaging with Medipix." Thesis, University of Canterbury. Physics and Astronomy, 2009. http://hdl.handle.net/10092/3863.
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Computed Tomography is one of the most important image modalities in
medical imaging nowadays. Recent developments have led to a new acquisition technique called 'dual-energy', where images are taken with different x-ray spectra. This enables for the first time spectral information in the CT dataset.
Our approach was to use an energy resolving detector (Medipix) and investigate its potential in the medical imaging domain. Images are taken
in different energy bins. For acquisition of the data, a CT scanner called 'Medipix All Resolution System' (MARS) scanner was constructed. It was upgraded to achieve better image quality as well as faster scan time and a stable operation.
In medical imaging, it is important to achieve a high contrast and a good detail recognition at a low dose. Therefore, it is common practice to use contrast agents to highlight certain regions of the body like e.g. the
vascular system. But with a broad spectrum acquisition, it is often impossible to distinguish highly absorbing body elements like bones from the contrast agent. We target this problem by a contrast agent study using different energy bins.
This so called spectral contrast agent study has been conducted with small animals using the MARS scanner. The data has been processed to create an optimal CT reconstruction. The image enhancement techniques consist of corrections for noisy pixels, intensity
fluctuations and eliminating
streaks in the sinograms to reduce ring artifacts.
In order to evaluate the data, we used two methods of material identification. The material reconstruction method works on projection data and uses a maximum-likelihood estimation to reconstruct images of base materials.
The second method, the principal component analysis (PCA), identifies
the relevant information from the spectral dataset in a few derived variables that account for most of the variance in the dataset. This resulted in images with enhanced contrast and removed redundancies. It is possible to combine these images in one colour image where anatomical structures are shown in good detail and certain materials show up in different colors.
Based on this new information from spectral data, we could show that it is possible to distinguish the spinal bone from contrast agent.
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Petrović, Nikola. "Measurement System for Microwave Imaging Towards a Biomedical Application." Doctoral thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-24878.
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Microwave imaging techniques have shown excellent capabilities in various fields such as civil engineering, nondestructive testing, industrial applications, and have in recent decades experienced strong growth as a research topic in biomedical diagnostics. Many research groups throughout the world work on prototype systems for producing images of human tissues in different biomedical applications, particularly breast tumor detection. However, the research community faces many challenges and in order to be competitive to other imaging modalities one of the means is to put emphasis on experimental work. Consequently, the use of flexible and accurate measurement systems, together with the design and fabrication of suitable antennas, are essential to the development of efficient microwave imaging systems. The first part of this thesis focuses on measurement systems for microwave imaging in terms of antenna design and development, robot controlled synthetic array geometries, permittivity measurements, and calibration. The aim was to investigate the feasibility of a flexible system for measuring the fields around an inhomogeneous object and to create quantitative images. Hence, such an aim requires solving of a nonlinear inverse scattering problem, which in turn requires accurate measurements for producing good quality experimental data. The presented solution by design of a flexible measurement system is validated by examination of microwave imaging from experimental data with a breast phantom. The second part of the thesis deals with the research challenges of designing high performance antennas to be placed in direct contact with or in close proximity to the imaged object. The need for novel antenna applicators is envisaged in the framework of the Mamacell measurement system, where the antenna applicators have to be designed and constructed to effectively couple the energy into the imaging object. For this purpose the main constraints and design requirements are a narrow lobe of the antenna, very small near-field effects, and small size. Numerical simulations and modeling shows that the proposed ridged waveguide antenna is capable of fulfilling the design requirements and the performance goals, demonstrating the potential for the future microwave imaging system called Mamacell.
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Sparks, Hugh. "Development and biomedical application of fluorescence lifetime imaging endoscopes." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/28962.
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A flexible wide-field fluorescence lifetime imaging (FLIM) endoscope is developed for clinical applications. For remote imaging, a coherent fibre optic bundle was used which required techniques and protocols to be developed to minimise artefacts associated with dispersion and recover accurate lifetime estimates. Potentially gain switched pulsed laser diodes are better suited for the clinic than light sources used conventionally for FLIM endoscopy because they are more compact and lower in cost. By imaging ex vivo human tissue samples, it was demonstrated that gain-switched pulsed laser diodes are a viable alternative excitation light source. The system was able to acquire ∼mm-scale spatial FLIM images from fresh ex vivo diseased human larynx biopsies. For wide-field FLIM with the fastest update rates, gated optical intensifiers (GOIs) are used as detectors. This thesis documents the characterisation of next generation GOI technology that can achieve larger than existing standard GOI standard gate-widths for improved light efficiency and that use a magnetic field to enhance spatial resolution beyond that of proximity focusing alone. For intra vital microscopy, access to tissue surfaces deep inside hollow or solid organs is challenging for microscopes. This thesis applies a commercially available confocal laser scanning endomicroscope (CLSE) adapted for time correlated single photon counting (TCSPC) FLIM to study protein interactions using based on Förster Resonance Energy Transfer (FRET) between fluorescent proteins. Protocols to minimise artefacts associated with dispersion in the CLSE’s fibre probe to recover accurate lifetime estimates are presented. To validate the design, the CLSE was used for a time-lapse study of live cancer cells in vitro to monitor their response to an inhibitor of the ERK intracellular signalling pathway by FLIM FRET of an extracellular signal-regulated kinase (ERK) biosensor.
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Monfort, Tual Remy. "Non linear photonics : developments & applications in biomedical imaging." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/422862/.
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Nonlinear polarization is explored in a biological and a technological contexts. Experimental set-ups are developed and built for interrogating nonlinear polarization in biological environment. Most notably, a Coherent Anti-Stokes Raman Scattering (CARS) and Second Harmonic Generation (SHG) microscopes are implemented in the Institute for Life Sciences (IfLS) at Southampton University. CARS and SHG are nonlinear effects based on different contrasts but both are label-free−and as a consequence truly in vivo; without perturbation of the biological mechanisms in opposition to fluorescence techniques (gold standard)− and enable fast imaging of living tissues, organisms and cells at 450 nm lateral spatial resolution. In collaboration with the mass-spectroscopy group at the General Hospital at Southampton and MedImmune, the capabilities of CARS & SHG are assessed for characterization of Pulmonary Alveoli Proteinosis (PAP) disease and drug impact on this phenotype and compared to its healthy version by tracking lipid droplets and collagen fibres. In an other collaboration with the clinical neuroanatomy and experimental neuropathology group at the University of Southampton, age related cerebrovascular and neurodegenerative diseases are linked to maternal obesity thanks to CARS thanks to its ability to track lipid droplets. In a second whole new project, multiplex CARS & SHG modalities are implemented and adapted to large area 4 mm2. Its methodology is developed. This last implementation allows microscopic and label-free characterization of large section of tissues which are compared to H&E (gold standard) valued by histological studies and proposed as a promising alternative. This ability leads to the development of a novel feature: texture analysis. The results obtained display novel insights and ability to characterize and localized healthy, pre-malignant and cancerous areas in tissues by a robust and unsupervised manner. Moreover, cancerous types could be further identified by this method. These results open up and bring the use of CARS & SHG for endoscopy/operative intervention for cancer/dysplasic localization at μm scale without prior labeling to an unprecedented level of specificity. To finish, a novel spectral CARS architecture is theoriticalized displaying unprecedented breadth and sensitivity; and enables the detection of many−usually too weak−biological Raman features.
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Ge, Haobo. "New functionalised carbon based nanomaterials for biomedical imaging applications." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.681050.
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Luthman, Anna Siri Naemi. "Spectrally resolved detector arrays for multiplexed biomedical fluorescence imaging." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274904.
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The ability to resolve multiple fluorescent emissions from different biological targets in video rate applications, such as endoscopy and intraoperative imaging, has traditionally been limited by the use of filter-based imaging systems. Hyper and multispectral imaging facilitate the detection of both spatial and spectral information in a single data acquisition, however, instrumentation for spatiospectral data acquisition is typically complex, bulky and expensive. This thesis seeks to overcome these limitations by using recently commercialised compact and robust hyper/multispectral cameras based on spectrally resolved detector arrays. Following sensor calibrations, which devoted particular attention to the angular sensitivity of the sensors, we integrated spectrally resolved detector arrays into a wide-field and an endoscopic imaging platform. This allowed multiplexed reflectance and fluorescence imaging with spectrally resolved detector array technology in vitro, in tissue mimicking phantoms, in an ex vivo oesophageal model and in vivo in a mouse model. A hyperspectral linescan sensor was first integrated in a wide-field near-infrared reflectance based imaging set-up to assess the suitability of spectrally resolved detector arrays for in vivo imaging of exogenous fluorescent contrast agents. Using this fluorescence hyperspectral imaging system, we could accurately resolve the presence and concentration of seven fluorescent dyes in solution. We also demonstrated high spectral unmixing precision, signal linearity with dye concentration, at depth in tissue mimicking phantoms, and delineation of four fluorescent dyes in vivo. After the successful demonstration of multiplexed fluorescence imaging in a wide-field set-up, we proceeded to combine near-infrared multiplexed fluorescence imaging with visible light spectral reflectance imaging in an endoscopic set-up. A multispectral endoscopic imaging system, capable of simultaneous reflectance and fluorescence imaging, was developed around two snapshot spectrally resolved detector arrays. In the process of system integration and characterisation, methods to characterise and predict the imaging performance of spectral endoscopes were developed. With the endoscope we demonstrated simultaneous imaging and spectral unmixing of chemically oxy/deoxygenated blood and three fluorescent dyes in a tissue mimicking phantom, and of two fluorescent dyes in an ex vivo oesophageal porcine model. With further developments, this technology has the potential to become applicable in medical imaging for detection of diseases such as gastrointestinal cancers.
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Dorcéna, Cassandre Jenny. "Nanoparticles for Biomedical Imaging and Biomolecular Transport and Manipulation." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1408915572.
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Kano, Angelique Lynn. "Ultrathin Single and Multi-Channel Fiberscopes for Biomedical Imaging." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/193617.
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Ultrathin fiberscopes typically have an imaging channel and an illumination channeland are available in diameters ranging from 0.5 mm to 2.5 mm. The minimum diam-eter can be reduced by combining the illumination and imaging paths into a singlefiberoptic channel. Constructing a single channel fiberscope requires a technique ofilluminating the tissue, while minimizing the Fresnel reflections and scatter withinthe common illumination and detection channel.A single channel fiberscope should image diffusely reflected light from tissue illu-minated with light filtered for the visible wavelength range (450 - 650 nm). Simplycombining the illumination and collection paths via a beamsplitter results in a lowobject to background signal ratio. The low contrast image is due to a low collectionefficiency of light from the ob ject as well as a high background signal from the Fresnelreflection at the proximal surface of the fiber bundle, where the illumination enters thefiber bundle. The focus of the dissertation is the investigation of methods to reducethe background signal from the proximal surface of the fiber bundle. Three systemswere tested. The first system uses a coherent fiber bundle with an AR-coating on theproximal face. The second system incorporates crossed polarizers into the light path.In addition, a technique was developed, whereby a portion of the image numericalaperture is devoted to illumination and a portion to image signal detection. Thistechnique is called numerical aperture sharing (NA sharing).This dissertation presents the design, construction, testing, and comparison ofthe three single channel fiberscopes. In addition, preliminary results of a study aimedat the usefulness of broadband diffuse reflectance imaging for the identification andtracking of disease progression in mouse esophagus are presented.
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Liang, Chen. "Design of miniature microscope objective optics for biomedical imaging." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280105.
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The topic of this dissertation is on the design and construction of miniature microscope objective optics. The design of miniature microscope objective is both similar and different from conventional microscope objective. The design and construction of two miniature microscope objectives are presented in this dissertation. The first one is a high numerical aperture (NA), water-immersion objective and it is a part of a fiber confocal reflectance microscope (FCRM). The second one is a moderate NA dry objective and it is a part of a miniature microscope array (MMA). The capability, complexity and fabrication method of the two miniature objectives are different but they both share some similar design traits as result of their miniaturization. FCRM's miniature objective has a NA of 1.0 and it is designed to operate at near infrared lambda = 1,064 nm. It is 7 mm in outer diameter and 21 mm in length (measured from object plane to image plane). This kind of dimension is approximately 10 times smaller than a conventional microscope objective of similar caliber. Sub-micrometer resolution has been experimentally demonstrated with this miniature objective. MMA's miniature objective has a NA of 0.4 and it is designed to operate over the visible spectrum. It is 1.2 mm in diameter and 9.4 mm in length. The image quality of MMA's miniature objective is experimentally demonstrated to be comparable to the state-of-art commercial microscope objective.
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Qin, Ruogu. "Intraoperative Imaging Platform." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1322617803.
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Schuessler, Thomas Florian. "Advances in pulmonary monitoring and thoracic imaging." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34444.
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The high incidence of pulmonary disease in critically ill patients necessitates new and improved techniques for pulmonary monitoring and thoracic imaging. To investigate pulmonary monitoring techniques using pressure and flow signals, I developed a comprehensive computational model of subjects breathing spontaneously or with the support of an assist-ventilator. The model was used to quantitatively assess measurement techniques for dynamic intrinsic positive end-expiratory pressure (PEEP$ rm sb{i})$ and inspiratory work of breathing. The results demonstrate that some means of correction for both expiratory muscle activity and cardiogenic oscillations on esophageal pressure is necessary if dynamic PEEP$ rm sb{i}$ and work of breathing are to be measured accurately on-line. I also conclude that the discrepancies between static and dynamic PEEP$ rm sb{i}$ are caused by heterogeneity of the expiratory flow limitation. An adaptive filter to reduce the cardiogenic oscillations on esophageal pressure was developed and validated in a computer simulation. In four intensive care patients, the adaptive filter markedly attenuated the apparent cardiogenic oscillations and reduced the standard deviation of the measured PEEP$ rm sb{i}$ by 57%. Investigation of the interactions between patients and a pressure support ventilator using the computer model confirmed our present understanding of patient-ventilator asynchrony and indicated that patient and ventilator form a highly nonlinear dynamic system, so that the optimal ventilator settings most likely vary between patients and with time. In the second part of this thesis, I investigated the importance of inaccuracies in conventional Finite Elements for thoracic Electrical Impedance Tomography (EIT) imaging. Augmenting the number of first-order Finite Elements did not efficiently reduce these inaccuracies. A computer simulation suggested that the accuracy of the forward solution needs to be improved by at least 30 dB before useful
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Taylor, Carmen Celeste. "Imaging methodology for assessment of chronic disease." Diss., Search in ProQuest Dissertations & Theses. UC Only, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3324621.
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Thesis (Ph.D.)--University of California, San Francisco with the University of California, Berkeley, 2008.Source: Dissertation Abstracts International, Volume: 69-09, Section: B, page: 5584. Adviser: Sharmila Majumdar.
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Hu, Simon. "Hyperpolarized carbon-13 magnetic resonance spectroscopic imaging: Pulse sequence development for compressed sensing rapid imaging and preclinical liver studies." Diss., Search in ProQuest Dissertations & Theses. UC Only, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3390048.
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Thesis (Ph.D.)--University of California, San Francisco with the University of California, Berkeley, 2009.Source: Dissertation Abstracts International, Volume: 71-02, Section: B, page: . Adviser: Daniel B. Vigneron.
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Gao, Ying Gao. "Development of Quantitative Fast Imaging with Steady-State Free Precession (FISP) Techniques for High Field Preclinical Magnetic Resonance Imaging." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1475150834919997.
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Shet, Keerthi Vishnudas. "Development Of Instrumentation And Techniques To Adapt Proton Electron Double Resonance Imaging For Biomedical Imaging." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1227731151.
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Stefanovic, Bojana. "Functional magnetic resonance imaging of cerebral blood volume." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85650.
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This dissertation describes a novel method for quantifying venous cerebral blood volume (CBVv) changes accompanying normal functional activation and employs quantitative functional magnetic resonance imaging (fMRI) methods to study the hemodynamic and metabolic changes accompanying neuronal inhibition. An in vivo occipital lobe relaxometry study was performed first to investigate the dependence of the spin-spin relaxation time constant of tissue, T2tissue , on the refocusing interval over the range of interest and thus test the basis of the proposed CBVv method. The small decrease of the apparent T2tissue with refocusing interval elongation is consistent with blood being the only significant source of refocusing interval dependence of apparent T2 in grey and white matter of the occipital lobe. In ensuing in vitro blood relaxometry studies, ensemble fitting of the entire set of T2blood estimates, obtained over an extensive range of blood oxygenation levels and refocusing intervals, was performed using both the fast chemical exchange model and the model of diffusion in weak magnetic field inhomogeneities. The results support the application of a diffusion model in describing the deoxyhemoglobin-induced enhancement in blood transverse relaxation rate at 1.5 T. Given the uniqueness of T2blood dependence on the refocusing rates over the range of interest, the novel CBVv method - venous refocusing for volume estimation (VERVE) - successfully isolates the blood signal by refocusing rate variation. A model of functional brain activation was developed and in vitro blood relaxometry data used to assess the effect of the intravascular spin-echo blood oxygenation level dependent (BOLD) contrast on the activation-induced VERVE signal change, allowing robust estimation of venous CBV changes. The method was demonstrated in a visual stimulation study of healthy young adults, where an average venous blood volume in the visual cortex increase was estimated
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Ifediba, Marytheresa Akuigwe. "Small Interfering RNA Imaging Probes for Neurological Applications." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10675.
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Small interfering RNAs (siRNAs) have emerged as a potent new class of therapeutics that regulate gene expression through sequence-specific inhibition of mRNA translation. Clinical trials of siRNAs have highlighted the need for robust delivery and detection techniques that would enable the application of these therapeutics to increasingly complex diseases and organ systems. Here we detail the generation and evaluation of siRNA-based optical and magnetic resonance imaging (MRI) contrast agents for the treatment of neurological diseases, including ischemic stroke and glioblastoma multiforme brain cancer. First, we designed and tested a fluorescent probe for neuroprotection in the setting of stroke that consists of siRNA complexed with myristoylated poly-arginine peptide (MPAP). MPAP, a peptide shown to cross cell membranes and the blood brain barrier, promoted robust internalization of siRNA by neurons in vitro and in mouse brain after intracerebral injection. Cellular uptake of MPAP-siRNA probes directed against a protein implicated in stroke pathology, c-Src, led to statistically-significant reductions of endogenous mRNA expression. The neuroprotective potential of probes was tested in a mouse model of ischemic stroke. Second, superparamagnetic iron oxide nanoparticles were investigated as vectors for siRNA delivery to glioblastoma multiforme brain tumors. Nanoparticles were designed to enhance chemotherapeutic treatment of tumors through siRNA-mediated knockdown of O6-methylguanine–DNA methyltransferase (MGMT), a protein implicated in glioblastoma chemotherapy resistance. The iron oxide core of nanoparticles rendered them detectable by MRI while fluorescent labeling was used for optical imaging. Functionalizing nanoparticles with the peptide chlorotoxin enabled tumor targeting and cellular accumulation of probe. Probe uptake was accompanied by reductions in MGMT activity and enhanced cellular responses to the chemotherapeutic temozolomide. Nanoparticles were tested in an orthotopic glioblastoma mouse model, where intratumoral administration proved effective in suppressing MGMT expression and tumor volume. These studies serve as proof-of-principle that siRNA-based imaging agents can be used as therapeutic tools for diseases of the central nervous system.Engineering and Applied Sciences
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Penmatsa, Madhuri Krishna. "Infrared Spectral Imaging Analysis Of Cartilage Repair Tissue." Master's thesis, Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/124100.
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BioengineeringM.S.
Articular cartilage is a homogenous tissue that provides frictionless movement between joints while withstanding repetitive physical stress. Once degenerated as a result of osteoarthritis or an injury, it has very limited capacity for self-repair. Recent research has focused on developing many new technologies for cartilage repair. The successful application of these strategies is limited in part to lack of techniques to evaluate tissue response to interventions. Assessment of the structural and molecular changes in the primary cartilage components, proteoglycan (PG) and collagen is critical to evaluate progress of the repair tissue. In the present study Fourier transform infrared imaging spectroscopy (FT-IRIS) was utilized to evaluate molecular changes in normal and degenerated cartilage in a rabbit model of repair. Parameters such as collagen integrity, type II collagen and proteoglycan are important factors in determining the biomechanical properties of articular cartilage, and are likely as important in determining functional competence of repair tissue. Histological evaluations are considered to be one of the most important methods for determining the quality of the repair tissue, but still do not predict clinical outcome. It is possible that a new tissue scoring system that considers molecular parameters in the repair tissue, along with the histological outcomes, will better predict clinical success of repair. The main goal of this study is to assess correlations between histological grading, immunohistochemical assessments of type I and II collagen, and FT-IRIS parameters, in cartilage repair tissue in a rabbit model. These data will provide the basis for a novel tissue scoring system using FT-IRIS parameters alone, or in conjunction with histological and immunohistochemical outcomes. This could yield better correlations with clinical outcomes that may lead to optimization of the cartilage repair process.
Temple University--Theses
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Guardiola, Garcia Marta. "Multi-antenna multi-frequency microwave imaging systems for biomedical applications." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/134967.
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Medical imaging refers to several different technologies that are used to view the human body in order to diagnose, monitor, or treat medical conditions. Each type of technology gives different information about the area of the body being studied depending on the radiation used to illuminate de body. Nowadays there are still several lesions that cannot be detected with the current methods in a curable stage of the disease. Moreover they present some drawbacks that limit its use, such as health risk, high price, patient discomfort, etc.
In the last decades, active microwave imaging systems are being considered for the internal inspection of light-opaque materials thanks to its capacity to penetrate and differentiate their constituents based on the contrast in dielectric properties with a sub-centimeter resolution. Moreover, they are safe, relatively low-cost and portable. Driven by the promising precedents of microwaves in other fields, an active electromagnetic research branch was focused to medical microwave imaging. The potential in breast cancer detection, or even in the more challenging brain stroke detection application, were recently identified. Both applications will be treated in this Thesis.
Intensive research in tomographic methods is now devoted to develop quantitative iterative algorithms based on optimizing schemes. These algorithms face a number of problems when dealing with experimental data due to noise, multi-path or modeling inaccuracies. Primarily focused in robustness, the tomographic algorithm developed and assessed in this thesis proposes a non-iterative and non-quantitative implementation based on a modified Born method. Taking as a reference the efficient, real-time and robust 2D circular tomographic method developed in our department in the late 80s, this thesis proposes a novel implementation providing an update to the current state-of-the-art. The two main contributions of this work
are the 3D formulation and the multi-frequency extension, leading to the so-called Magnitude Combined (MC) Tomographic algorithm. First of all, 2D algorithms were only applicable to the reconstruction of objects that can be assumed uniform in the third dimension, such as forearms. For the rest of the cases, a 3D algorithm was required. Secondly, multi-frequency information tends to stabilize the reconstruction removing the frequency selective artifacts while maintaining the resolution of the higher frequency of the band.
This thesis covers the formulation of the MC tomographic algorithm and its assessment with medically relevant scenarios in the framework of breast cancer and brain stroke detection. In the numerical validation, realistic models from magnetic resonances performed to real patients have been used. These models are currently the most realistic ones available to the scientific community. Special attention is devoted to the experimental validation, which constitutes the main challenge of the microwave imaging systems. For this reason, breast phantoms using mixtures of chemicals to mimic the dielectric properties of real tissues have been manufactured and an acquisition system to measure these phantoms has been created. The results show that the proposed algorithm is able to provide robust images of medically realistic scenarios and detect a malignant breast lesion and a brain hemorrhage, both at an initial stage.
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Ragib, Husain B. Wang Yu-Ping. "Wavelet transform based peak detection with application to biomedical imaging." Diss., UMK access, 2004.
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Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2004."A thesis in computing and electrical engineering." Typescript. Advisor: Yu-Ping Wang. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 28, 2006. Includes bibliographical references (leaves 77-81). Online version of the print edition.
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Chen, Andy Yen Hsin. "Development and characterization of fiber-based systems for biomedical imaging." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/13361.
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This thesis focuses on the instrumentation aspect of biomedical imaging with the use of optical fiber probes across three different disciplines. This includes the design and development of novel fiber optic based techniques and instruments in fields of optical coherence tomography (OCT), bioremediation and optical mapping of cardiac action potentials. Although the mechanism behind the imaging techniques of fluorescence and OCT are fundamentally different, the fact that both techniques permit the use of fiber probes gives rise to the possibility of a combined fluorescence-OCT probe. For example, the OCT and fluorescence portions of the integrated system are optically distinct, except for the final optics of the fluorescence-OCT fiber probe. Analog processing electronics for the subsystems can also be distinct, but for the purpose of synchronization and simultaneous data acquisition, both should be controlled by a central computer. Tumlinson and co-workers [140] have already demonstrated the development of such a system for simultaneous optical coherence tomography and laser-induced fluorescence measurement. We begin by demonstrating the feasibility of using the novel source, supercontinuum, in an OCT system. Its capabilities and limitations are also discussed. A prototype all-fiber OCT system was subsequently constructed to meet the design requirements of combined fluorescence-OCT probes. Current bioremediation methods are hindered by the lack of reliable, non-destructive, and in situ monitoring techniques. We investigate the feasibility of developing a novel spectroscopic technique that can monitor bacterial species in situ. A fluorescence spectroscopy system that meets the design criteria is subsequently built. Its capabilities and limitations were demonstrated through a series of laboratory controlled experiments which showed promising preliminary results. Optical mapping of cardiac action potential have proved to be indispensable in the study of arrhythmia. Although optical recordings using optical fibers have already been demonstrated with convincing results, none of which were spectrally resolved. We have constructed a fluorescence setup to make spectroscopic measurement of cardiac action potentials. This has offered more insights into the complex process of spectral modulation which is usually associated with membrane potential and mechanical activity.
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Qin, Haiyan. "Rational design of nanoparticles for biomedical imaging and photovoltaic applications." Doctoral thesis, KTH, Teoretisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33346.
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This thesis aims to rationally design nanoparticles and promote their applications in biomedical imaging and photovoltaic cells. Quantum dots (QDs) are promising fluorescent probes for biomedical imaging. We have fabricated two types of MSA capped QDs: CdTe/ZnSe core/shell QDs synthesized via an aqueous method and CdTe QDs via a hydrothermal method. They present high quantum yields (QYs), narrow emission band widths, high photo- and pH-stability, and low cytotoxicity. QD-IgG probes were produced and applied for labeling breast cancer marker HER2 proteins on MCF-7 cells. For the purpose of single molecule tracking using QDs as fluorescent probes, we use small affibodies instead of antibodies to produce QD-affibody probes. Smaller QD-target protein complexes are obtained using a direct immunofluorescence approach. These QD-affibody probes are developed to study the dynamic motion of single HER2 proteins on A431 cell membranes. Fluorescence blinking in single QDs is harmful for dynamic tracking due to information loss. We have experimentally studied the blinking phenomenon and the mechanism behind. We have discovered an emission bunching effect that two nearby QDs tend to emit light synchronously. The long-range Coulomb potential induced by the negative charge on the QD surface is found to be the major cause for the single QD blinking and the emission bunching in QD pairs. We have studied the in vitro cytotoxicity of CdTe QDs to human umbilical vein endothelial cells (HUVECs). The QDs treatment increases the intracellular reactive oxygen species (ROS) level and disrupts the mitochondrial membrane potential. The protein expression levels indicate that the mitochondria apoptosis is the main cause of HUVCEs apoptosis induced by CdTe QDs. Gold nanorods (GNRs) are scattering probes due to their tunable surface plasmon resonance (SPR) enhanced scattering spectrum. In order to control the yield and morphology of GNRs, we have systematically studied the effects of composition and concentration in the growth solution on the quality of the GNRs produced via a seed-mediated method. The aspect ratios of GNRs were found to be linearly depended on the concentration ratio of silver ions and CTAB. The high quality GNRs obtained were adsorbed to COS-7 cell membranes for dark field imaging. We have rationally designed two types of QDs by wave function engineering so as to improve the efficiency of QD-sensitized solar cells. A reversed type-I CdS/CdSe QD confines excitons in the shell region, whereas a type-II ZnSe/CdS QD separates electrons in the shell and holes in the core. Their absorbed photon-to-current efficiencies (APCE) are as high as 40% and 60% respectively. In conclusion, rationally designed nanoparticles are proven a high potential for applications as probes in biomedical labeling, imaging and molecule tracking, and as sensitizers for photovoltaic cells.QC 20110511
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Lucka, Felix [Verfasser], and Martin [Akademischer Betreuer] Burger. "Bayesian inversion in biomedical imaging / Felix Lucka ; Betreuer: Martin Burger." Münster : Universitäts- und Landesbibliothek Münster, 2015. http://d-nb.info/1138279749/34.
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