Dissertations / Theses on the topic 'Tomographic technique'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Tomographic technique.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Jacobsson, Svärd Staffan. "A Tomographic Measurement Technique for Irradiated Nuclear Fuel Assemblies." Doctoral thesis, Uppsala University, Department of Nuclear and Particle Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4227.
Full textThe fuel assemblies used at the Swedish nuclear power plants contain typically between 100 and 300 fuel rods. An experimental technique has been demanded for determining the relative activities of specific isotopes in individual fuel rods without dismantling the assemblies. The purpose is to validate production codes, which requires an experimental relative accuracy of <2 % (1 σ).
Therefore, a new, non-destructive tomographic measurement technique for irradiated nuclear fuel assemblies has been developed. The technique includes two main steps: (1) the gamma-ray flux distribution around the assembly is recorded, and (2) the interior gamma-ray source distribution in the assembly is reconstructed. The use of detailed gamma-ray transport calculations in the reconstruction procedure enables accurate determination of the relative rod-by-rod source distribution.
To investigate the accuracy achievable, laboratory equipment has been constructed, including a fuel model with a well-known distribution of 137Cs. Furthermore, an instrument has been constructed and built for in-pool measurements on irradiated fuel assemblies at nuclear power plants.
Using the laboratory equipment, a relative accuracy of 1.2 % was obtained (1 σ). The measurements on irradiated fuel resulted in a repeatability of 0.8 %, showing the accuracy that can be achieved using this instrument. The agreement between rod-by-rod data obtained in calculations using the POLCA–7 production code and measured data was 3.1 % (1 σ).
Additionally, there is a safeguards interest in the tomographic technique for verifying that no fissile material has been diverted from fuel assemblies, i.e. that no fuel rods have been removed or replaced. The applicability has been demonstrated in a measurement on a spent fuel assembly. Furthermore, detection of both the removal of a rod as well as the replacement with a non-active rod has been investigated in detail and quantitatively established using the laboratory equipment.
Jacobsson, Svärd Staffan. "A tomographic measurement technique for irradiated nuclear fuel assemblies /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4227.
Full textMALALLA, NUHAD ABDULWAHED YOUNIS. "C-ARM TOMOGRAPHIC IMAGING TECHNIQUE FOR DETECTION OF KIDNEY STONES." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/dissertations/1278.
Full textKim, Chuyoung. "Algorithms for Tomographic Reconstruction of Rectangular Temperature Distributions using Orthogonal Acoustic Rays." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73754.
Full textMaster of Science
Sik, Ayhan Serkan. "X-ray Physics And Computerized Tomography Simulation Using Java And Flash." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/3/756239/index.pdf.
Full textPaduelli, Marcela Candian. "Estudo da técnica de ondas de tensão como instrumento de avaliação interna de árvores urbanas." Universidade Federal de São Carlos, 2011. https://repositorio.ufscar.br/handle/ufscar/4180.
Full textFinanciadora de Estudos e Projetos
Arborization is fundamental in urban spaces, due to the significant benefits it provides. To important issue to guarantee the adequacy of the role it plays is its maintenance. To this purpose, an application of preventive methods of diagnosis is recommended, allowing the evaluation of external and internal conditions of tress. Currently, the analysis of urban trees is subjectivity. For a complete and secure analysis, it is important to associate this visual external analysis to an internal analysis. This could be done by applying non-destructive techniques, wich allows an internal visualization of the tree through a tomographic image, without causing it any damage. Among the non-destructive techniques, that have applicability in the internal evaluation of urban trees, the technique of stress waves can be highlighted. Considering the great benefits that this technique can provide in the evaluation of urban trees, this research seeks to verify its scientific and technique viability, analyzing its reliability and also establishing some parameters of application. Studies with 12 trees of the Caesalpinea peltophoroides species (popularly known as Sibipiruna) have been carried out. The stress waves equipment was applied to sections of 50, 90 and 130 cm from the trees basis, generating tomographic images of these sections. Afterwards, the trees were cut at the level of these sections and, in order to compare these images, some pictures of them were made. The results show that the trees waves technique presents large applicability for internal evaluation of urban trees, achieving significant results. Also some parameters for the application of this technique were established. For instance, it is necessary to determinate the speed reference of waves propagation for the interpretation of tomographic images, as well as it is to determinate the best height of the assays section. The latter consisting on the height of the diameter to the chest height (DAP), where average density of the tree is representative.
A arborização é fundamental nos espaços urbanos, devido aos importantes benefícios que proporciona. Para garantir que esta exerça adequadamente seu papel, é importante a sua manutenção, na qual é necessário o emprego de métodos de diagnóstico preventivos, que permitam avaliar as condições externas e internas das árvores. Atualmente, a análise de árvores urbanas é realizada basicamente pela análise visual externa, a qual apresenta grande subjetividade. Para uma análise completa e segura é importante que a análise visual externa seja acompanhada de uma análise interna. Esta pode ser realizada por meio de técnicas nãodestrutivas, que possibilitam a visualização interna da árvore através da imagem tomográfica, sem causar nenhum dano a esta. Dentre as técnicas não-destrutivas existentes, com aplicabilidade na avaliação interna de árvores urbanas, pode-se destacar a técnica de ondas de tensão. Diante dos grandes benefícios que esta técnica pode proporcionar na avaliação de árvores urbanas, esta pesquisa buscou verificar sua viabilidade técnica e científica, analisando a sua confiabilidade e estabelecendo parâmetros para sua aplicação. Foram realizados estudos com 12 árvores da espécie Caesalpinea peltophoroides (conhecida popularmente como Sibipiruna), nas quais foram realizadas medições em seções a 50, 90 e 130 cm da base, empregando o equipamento de ondas de tensão, o qual gerou as imagens tomográficas das seções. Em seguida, as árvores foram cortadas nas seções de ensaio e fotografadas, para posterior comparação com a imagem tomográfica gerada. Os resultados permitiram verificar que a técnica de ondas de tensão apresenta grande viabilidade de aplicação na avaliação interna de árvores urbanas, com resultados bastante significativos. Foi possível também estabelecer alguns parâmetros de aplicação da técnica, como a necessidade da determinação da velocidade de propagação da onda de referência, para a interpretação da imagem tomográfica e a determinação da melhor altura da seção para realização dos ensaios, a qual consistiu na altura do diâmetro à altura do peito (DAP), na qual se encontra a representatividade da densidade média da árvore.
Boutet, Jérôme. "Localisation d'inclusions fluorescentes dans les milieux diffusants à l'aide de techniques laser. Application au diagnostic médical in vivo." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENY009/document.
Full textFluorescence tomography is a preclinical and clinical imaging method which aims to localize fluorescent probes injected into a living organism. In this thesis work, we defined the optimal design and parameters of a continuous wave fluorescent tomograph applied to thin tissue observation. We handled the problem of observing heterogeneous and highly absorbing organs. Secondly, we showed the advantage of time of flight measurement for inclusion detection through thicker tissues. The detection performances of two types of system capable of these measurements were compared and we proposed a protocol to optimize their main parameters. This process was applied to the problematic of prostatic biopsy guiding. It would also be used to detect and localize other pathologies by means of a simple adaptation
Breckon, W. R. "Image reconstruction in Electrical Impedance Tomography." Thesis, Oxford Brookes University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292254.
Full textPratte, Jean-François. "Conception d'un amplificateur filtre rapide en CMOS 0.35 um destiné à un tomographe à émission de positrons animal." Sherbrooke : Université de Sherbrooke, 2002.
Find full textŞık, Ayhan Serkan. "X-ray physics and computerized tomography simulation using java and flash." Ankara : METU, 2003. http://etd.lib.metu.edu.tr/upload/756239/index.pdf.
Full textKeywords: Keywords: Radiation interaction with matter, cross section of interaction, radiation generation and detection, computerized tomographic imaging, Java/Flash simulations.
Lundqvist, Saleh Tobias. "Tomographic Techniques for Safeguards Measurements of Nuclear Fuel Assemblies." Licentiate thesis, Uppsala universitet, Institutionen för neutronforskning, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-85831.
Full textDeng, Junjun. "Parallel computing techniques for computed tomography." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/945.
Full textDesaubry, Christophe. "Conception de deux dispositifs expérimentaux pour la vélocimétrie par imagerie de particules : Application aux écoulements basse vitesse." Lyon, INSA, 1995. http://www.theses.fr/1995ISAL0111.
Full text[The study of heat transfer that appears in convective flows needs a very good knowledge of low velocity flow dynamic. The laser visualization is actually a technic witch is commonly used for qualitative flow description. Particle Image Velocimetry (P. I. V), recently developed, is derived from the proceeding technical. The P. I. V quantitative method allows to extract informations concerning two dimensionnal velocity field from a double-exposed image of the fluid in motion. Two experimental setups are described in this work. Both are based on the standard video catching technical and on numerical technical often used in P. I. V measurements. A systematic and comparative analysis of the two setups is made by considering different applications allowing several fluid flow mechanisms. ]
Choi, Young Jin. "Application of tomographic techniques for rheological measurements and process control /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
Full textCollaer, Marcia Lee. "IMAGE DATA COMPRESSION: DIFFERENTIAL PULSE CODE MODULATION OF TOMOGRAPHIC PROJECTIONS." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/291412.
Full textTeichmann, Ulrich, Astrid Ziemann, Klaus Arnold, and Armin Raabe. "Akustische Tomographie und optische Scintillometertechnik zur Sondierung der atmosphärischen Grenzschicht." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-214141.
Full textDuring an experiment at the Iff field research station Melpitz in September 1997 for the first time two different techniques were used to determine simultaneously area averaged air temperatures (Acoustic Tomography -LIM) and line averaged sensible heat fluxes (Scintillation technique - IfT). lt could be shown that on a \'golden\' day appreciably large temperature differences occurred on this superficially considered horizontal homogeneous meadow. Because of the weak data base mostly due to difficult fetch conditions it could not be proven that these temperature differences led to the horizontal differences of vertical sensible heat fluxes and therefore to the sometimes observed non-closure of the energy balance in Melpitz
Murcia, Jérôme de. "Reconstruction d'images cardiaques en tomographie d'émission monophotonique à l'aide de modèles spatio-temporels." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0078.
Full textLeung, Hing Tong Lucullus. "Development of an electrical impedance tomograph for complex impedance imaging." Thesis, University of South Wales, 1991. https://pure.southwales.ac.uk/en/studentthesis/development-of-an-electrical-impedance-tomograph-for-complex-impedance-imaging(b3f26e76-490d-4364-a270-28cff1dccd70).html.
Full textLaidlaw, James Stuart. "Tomographic techniques and their application to geotechnical and groundwater flow problems." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/28493.
Full textScience, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
王晴兒 and Ching-yee Oliver Wong. "Measurement of cerebrovascular perfusion reserve using single photon emission tomographic techniques." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31981677.
Full textBhatia, Mickey. "Wavelet transform-based multi-resolution techniques for tomographic reconstruction and detection." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11650.
Full textNikitidis, Michail S. "Application of gamma-ray tomographic techniques in granular flows in hoppers." Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/844103/.
Full textSharaf, Jamal Mahmood. "Elemental analysis of biological matrices using emission and transmission tomographic techniques." Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/844448/.
Full textWong, Ching-yee Oliver. "Measurement of cerebrovascular perfusion reserve using single photon emission tomographic techniques." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19605328.
Full textBourret, Rodolphe. "Etude d'algorithmes de reconstruction en tomographie d'impédance : technique analytique et technique numérique par la méthode des éléments finis." Toulouse 3, 1990. http://www.theses.fr/1990TOU30047.
Full textXie, Yao. "Adaptive and Robust Techniques (ART) for thermoacoustic tomography." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015243.
Full textGoulet, Mathieu. "Application of tomography techniques to plastic scintillation dosimetry." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30599/30599.pdf.
Full textThis thesis deals with the development of tools for the quality assurance of external beam radiotherapy. The main goal is to incorporate tomography processes to plastic scintillator dosimetry in order to conceive high resolution, precise, accurate and easy-to-use quality assurance devices. First, a long scintillating fiber response to an incoming radiation field is studied, and a fluence monitoring device is developed for the real-time validation of radiotherapy treatments. Using the light signal emitted from both sides of each fiber, both the interaction position of the incoming field and the fluence integral across the fiber can be measured, allowing for the detection of leaf errors of at least 2 mm at isocentre. The theoretical response model previously developed is then applied to the tomographic reconstruction of dose distributions measured using a rotating matrix of long scintillating fibers. The dose reconstructed using this 2D dosimeter is in agreement with the calculations from the treatment planning software up to a maximum difference of 2% in the low dose gradient regions. The concept of tomographic dosimetry, or tomodosimetry, is then applied to 3D dose measurements using concentric, cylindrical planes of fibers. By simulating the rotation of these planes around the dosimeter central axis and by interpolating in three dimensions the obtained 2D doses, the 3D dosimeter is able to reconstruct the initial input dose with a deviation of maximum 1% outside of high dose gradient regions. Finally, the iterative reconstruction principles demonstrated for long scintillating fibers are applied to a scintillator volume imaged using a plenoptic camera. By re-projecting the projections acquired by the camera sensor pixels inside the scintillator volume, the 3D dosimeter is able to reconstruct the dose in real time with a maximal deviation of 3% in the low dose gradient regions. This study concludes that the union of tomography and dosimetry enables the development of a new generation of quality assurance devices, combining both spatial resolution and user-friendliness.
Tableau d'honneur de la FÉSP
Ettehadi, Seyedrohollah. "Model-based and machine learning techniques for nonlinear image reconstruction in diffuse optical tomography." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11895.
Full textAbstract : Diffuse optical tomography (DOT) is a low cost and noninvasive 3D biomedical imaging technique to reconstruct the optical properties of biological tissues. Image reconstruction in DOT is inherently a difficult problem, because the inversion process is nonlinear and ill-posed. During DOT image reconstruction, the optical properties of the medium are recovered from the boundary measurements at the surface of the medium. In this work, two approaches are proposed for non-linear DOT image reconstruction. The first approach relies on the use of iterative model-based image reconstruction, which is still under development for DOT and that can be found in the literature. A 3D forward model is developed based on the diffusion equation, which is an approximation of the radiative transfer equation. The forward model developed can simulate light propagation in complex geometries. Additionally, the forward model is developed to deal with different types of optical data such as continuous-wave (CW) and time-domain (TD) data for both intrinsic and fluorescence signals. First, a multispectral image reconstruction algorithm is developed to reconstruct the concentration of different tissue chromophores simultaneously from a set of CW measurements at different wavelengths. A second image reconstruction algorithm is developed to reconstruct the fluorescence lifetime (FLT) of different fluorescent markers from time-domain fluorescence measurements. In this algorithm, all the information contained in full temporal curves is used along with an acceleration technique to render the algorithm of practical use. Moreover, the proposed algorithm has the potential of being able to distinguish more than 3 FLTs, which is a first in fluorescence imaging. The second approach is based on machine learning techniques, in particular deep learning models. A deep generative model is proposed to reconstruct the fluorescence distribution map from CW fluorescence measurements. It is the first time that such a model is applied for fluorescence DOT image reconstruction. The performance of the proposed algorithm is validated with an optical phantom and a fluorescent marker. The proposed algorithm recovers the fluorescence distribution even from very noisy and sparse measurements, which is a big limitation in fluorescence DOT imaging.
Teague, Gavin. "Mass flow measurement of multi-phase mixtures by means of tomographic techniques." Doctoral thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/5097.
Full textThis thesis investigates the use of a dual-plane impedance tomography system to calculate the individual mass flow rates of the components in an air-gravel-seawater mixture. The long-term goal of this research is to develop a multi-phase flowmeter for the on-line monitoring of an airlift used in an offshore mining application. This requires the measurement of both the individual component volume fractions and their velocities. Tomography provides a convenient non-intrusive technique to obtain this information. Capacitance tomography is used to reconstruct the dielectric distribution of the material within a pipeline. It is based on the concept that the capacitance of a pair of electrodes depends on the dielectric distribution of the material between the electrodes. By mounting a number of electrodes around the periphery of the pipeline, and measuring the capacitances of the different electrode combinations, it is possible to reconstruct the distribution of the phases within the pipeline, provided the phases have different dielectric constants. Resistance tomography is used to reconstruct the resistivity distribution within the cross-section of the pipeline and operates in a similar way to capacitance tomography. Impedance tomography can be described as a dual-modal approach since both the capacitance and conductance of the different electrode combinations are measured to reconstruct the omplex impedance of the material distribution. Previous research has shown that impedance tomography can be used to reconstruct a three-phase air-gravelwater mixture [3,4]. In addition, it has been shown that neural networks can be used to perform this reconstruction task [3,4]. In particular, a single-layer feed-forward neural network with a 1-of-C output encoding can be trained to perform a three-phase image reconstruction. Further, a double-layer feed-forward neural network can be trained to predict the volume fractions of the three phases within the flow directly, based on the capacitance and conductance readings obtained from the data acquisition system. However, these tests were only for static configurations. This thesis will readdress this problem from the dynamic viewpoint. In addition, the individual component velocities will be calculated using the cross-correlation of the volume fraction predictions from two impedance tomography systems spaced a certain distance apart.
Chin, Kimberley Germaine. "An investigative study of the applicability of the convolution method of geophysical tomography." Ohio : Ohio University, 1985. http://www.ohiolink.edu/etd/view.cgi?ohiou1183751187.
Full textIngels, Alexandre. "Développement de techniques d’imageries pour le diagnostic et le pronostic des tumeurs du rein." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS451/document.
Full textThe aim of this project is the development of new imaging techniques for renal cancer diagnostic and treatment.We have assessed several techniques including optical coherence tomography and molecular imaging. We assessed a series of potential markers for molecular imaging by measuring some pre-defined markers expressions by immunohistochemistry in renal cell carcinoma and their association with disease’s prognostic. Finally, we assessed two molecular imaging techniques in pre-clinical models: Molecular Magnetic Resonance Imaging and Molecular Ultrasound Imaging
Michelet, Claire. "Développement d'une technique de micro-tomographie par faisceau d'ions à l'échelle cellulaire." Bordeaux 1, 1998. http://www.theses.fr/1998BOR10638.
Full textDupre, Antoine. "Electrical impedance tomography for void fraction measurements of harsh two-phase flows : prototype development and reconstruction techniques." Thesis, Ecole centrale de Marseille, 2017. http://www.theses.fr/2017ECDM0005/document.
Full textRecent developments with data acquisition equipment have reduced the time required for image acquisition with electrical tomography, thereby bringing new opportunities for the study of fast-evolving two-phase flows. Amongst the numerous advantages of this imaging technique for multiphase flow related research are non-intrusiveness, high acquisition rates, low-cost and improved safety. A set of electrodes placed on the periphery of the pipe to be imaged is used to impose an electrical excitation and measure the system response. The distribution of phases inside the study volume distorts the electrical field in a characteristic manner. The objective of this thesis is to assess the potential of electrical impedance tomography at high acquisition rate. The first stage consists in developing a prototype sensor and assessing its performance with simplistic experiments. The system architecture employs voltage control of the excitation and therefore does not require the implementation of the conventional voltage-to-current converter module. A novel data collection method, the full scan strategy, is considered and provides correcting factors for the parasitic impedances in the system. The second stage is the image reconstruction from the measurement data. The approach considered in the thesis is to assume that flow regime identification techniques may provide valuable information on the phase distribution that can be injected in the inverse problem for imaging, thereby tackling the challenge of the non-linearity of the inverse problem. A method for horizontal air-water flow regime identification has been elaborated with an electrical capacitance tomography sensor and multiphase flow rig tried and tested. It is being adapted to the fast electrical impedance tomography prototype and upgraded to include vertical flow regimes. In parallel, an image reconstruction method has been developed based on the NOSER algorithm and a pseudo-2D postulate. The analysis of the reconstructed images for a set of benchmark experiments provide insights on the merits and deficiencies of the algorithm and of the prototype
Selivanov, Vitali. "Topics in image reconstruction for high resolution positron emission tomography." Thèse, Sherbrooke : Université de Sherbrooke, 2002. http://savoirs.usherbrooke.ca/handle/11143/4169.
Full textMéteau, Jérémy. "Instrumentation optique pour la caractérisation des tissus : analyse de la complémentarité et des limites techniques de fluorescence hyperspectrale et de Tomographie Optique Cohérente en vue de leur intégration multimodale." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2041/document.
Full textThe aim of this activity is the development of a mono point imaging fiber system which uses hyperspectral multi-excitation auto fluorescence technique for biological tissues and the study of an Optical Coherence Tomography system like another modality. At first, this report presents the optical properties of biological tissues and the relevant fluorophores for cancerous tumors detection. Secondly, the fluorescence imaging system instrumentation and hyperspectral analysis are presented with in vitro results. The third part presents the "scan free" optical coherence tomography system which is able to image without optical displacement. It's characterized and have interesting functionality like depth dependant dispersion compensation. These both techniques are complementary because they get different kind of information. The information of the first one is about biochemical composition of the tissues and the information of the second one is about the stucture
Pal, Sandip. "Sensitive Detection Techniques and Systems for Minor Species Tomography." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503005.
Full textKyte, David John. "Magnetic induction tomography and techniques for eddy-current imaging." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/707/.
Full textBayford, R. H. F. W. "Application of constrained optimisation techniques in electrical impedance tomography." Thesis, Middlesex University, 1994. http://eprints.mdx.ac.uk/13280/.
Full textKtistis, Christos. "Electromagnetic induction tomography techniques for low conductivity biomedical application." Thesis, University of Manchester, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682783.
Full textKusminarto. "Study and development of techniques in computerised neutron tomography." Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/844567/.
Full textMoussallem, Mazen. "Optimisation de la délimitation automatique des tumeurs pulmonaires à partir de l'imagerie TEP/TDM pour les planifications dosimétriques des traitements par radiothérapie." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00864905.
Full textFincke, Jonathan Randall. "Non-contact quantitative imaging of limbs, bone and tissue, using ultrasound tomographic techniques." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119342.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 123-131).
Non-contact and quantitative ultrasound images of bone and soft tissue are produced from original algorithms applied to observational data sets collected on two custom built ultrasound imaging systems for limb imaging. The images are quantitative in that the distribution of sound speeds and dimensionally accurate geometry of tissue structures are reconstructed. The first imaging system is based on laser generation and detection of ultrasound (LUS) and the second is a water immersion ultrasound tomography (UST) system. The LUS and UST systems and algorithms, in aggregate, can be used to generate large volume, quantitative 2D and traditional 2D ultrasound images. Existing medical ultrasound systems are unable to acquire or generate large volume, quantitative and clinically useful bone images. A medical ultrasound system with these capabilities would have significant clinical value. LUS and UST systems could improve the quality, cost and safety of osteoporosis diagnosis and tracking, prosthetic fitting, bone fracture detection and tracking, intraoperative imaging and volumetric imaging in intensive care units. The algorithms and systems established for this thesis contribute broadly to non-contact ultrasound imaging: LUS for medical imaging, and UST for bone and soft tissue imaging and quantification. Non-contact techniques are clinically valuable because they can deliver operator independent image quality and large volume imagery without making contact with the body and distorting the tissue. Quantitative ultrasound imaging techniques are clinically useful because they provide intrinsic information about tissue mechanical properties, such as stiffness and density. Successful bone and soft tissue quantification using UST techniques could yield an entirely new and radiation free means of assessing bone and soft tissue strength and health. The experiments completed with the LUS system demonstrate its capability to generate images without contacting or treating the skin surface. Further, soft tissue (weak reflector), as well as bone (strong reflectors) are resolved at skin safe optical exposures. To enhance the LUS system performance, the optical wavelength of the generation laser is studied and optimized to deliver the largest acoustic source possible while also meeting optical exposure thresholds for skin. Additionally, commercially available laser vibrometer technology optimized for detecting vibrations on rough surfaces, such as skin, is identified and tested. Three original algorithms yield images of bone and soft tissue geometry and sound speed when applied to experimental data from the UST device. The first algorithm is a backscatter/reflection adaptive imaging technique that enables high resolution, SNR and volumetric imagery of bone and soft tissue to be formed from a single, mechanically scanned ultrasound transducer. The second algorithm uses a travel-time sound speed inversion technique that estimates water, soft tissue and bone sound speed to within 10% of ground truth estimates. The performance of this algorithm is validated on multiple samples and a simulated data set. The third algorithm is a full waveform inversion (FWI) algorithm regularized with the level set technique to enable quantification of bone properties. This algorithm is validated on an animal tissue sample and simulated data sets. The FWI technique resolves the soft tissue spatial sound speed distribution with half to one-quarter wavelength (1 - 0.5 mm) resolution and average sound speed values are within 10% of ground truth measurements.
by Jonathan Randall Fincke.
Ph. D.
Bisel, Tucker. "Investigation into the Capabilities and Characteristics of Tomographic Particle Image Velocimetry Measurement Techniques." Thesis, The University of North Carolina at Charlotte, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10815987.
Full textLiterature describing measurement results obtained using tomographic particle image velocimetry (TomoPIV) systems has become increasingly common, but details on the processes used to obtain those results and reasons for selecting specified analysis settings are not often explained. In this thesis, an overview is given of techniques and methodologies found to be useful when conducting TomoPIV measurements using an asymmetric four-camera system, including image pre-processing techniques and methods of improving analysis settings. Effective image pre-processing techniques include background subtraction for removing static background noise and improving signal-to-noise ratios and a customized filter that easily and reliably increases voxel reconstruction speed and reduces memory requirements. The custom filter acts to concentrate light intensity around particle locations while muting background pixel intensities. The effects on final measurement results are observed for voxel reconstruction and 3D least squares matching (LSM) settings, including relaxation number, reconstruction iterations, and interrogation volume size. The effects of surface reflections of laser light on TomoPIV results are also investigated by comparing measurement results of a cubic bluff body painted first with a flat white aerosol paint, and second with an airbrushed Rhodamine 6G fluorescent paint. Fluoresced light is blocked by bandpass filters, resulting in minimal reflections from the Rhodamine 6G paint and no observed impact on measurement results. White paint results in intense surface reflections and increased image noise, preventing reliable recognition of distant particles. Comparison of averaged 3D vector map results for both coatings reveals that allowable measurement depth decreases as surface reflection intensity increases.
Peteya, Jennifer Anita. "Resolving Details of the Nonbiomineralized Anatomy of Trilobites Using Computed Tomographic Imaging Techniques." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366025146.
Full textLundqvist, Tobias. "Investigation of Algebraic Reconstruction Techniques for Tomographic Measurements on Spent Nuclear Fuel Assemblies." Thesis, Uppsala universitet, Institutionen för strålningsvetenskap, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-307832.
Full textYao, Rutao. "Development of multispectral scatter correction techniques for high-resolution positron emission tomography." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq26405.pdf.
Full textHassoun, Alain. "Quantification des erreurs de reconstruction dues aux variations aléatoires des mesures en tomographie d'émission : comparaison expérimentale des techniques intervallistes et statistiques." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20272.
Full textIn nuclear medicine, Single-Photon Emission Computed Tomography (SPECT) images are used to diagnose a certain number of degenerative diseases such as Parkinson's disease. The principle of this kind of diagnosis is to compare the activity reconstructed in two specific regions of interest. The random fluctuations of the reconstructed activities, due to the random fluctuations of the measurement, have unknown statistical properties. This lack of knowledge makes the comparison, and thus the diagnosis, unreliable. To make the diagnosis more reliable, it is important to quantify the impact of random fluctuations of the projection measurements on the reconstructed activities in each region of interest.In this thesis, we focused on this quantification by using reconstruction methods based on a new modelling of the acquisition tomography process. A special feature of the obtained reconstructions is that the reconstructed activities are not precise- but interval-valued activities. The width of the reconstructed intervals quantifies the reconstruction error. As important contribution, we have proposed a protocol derived from the quantitative comparison method applied in clinical routine. This protocol can be used to evaluate the performance of an error quantification algorithm or, to compare the performances of two quantification algorithms. We show and discuss the performance of two interval-based quantification methods and a chosen reference method
Nguyen, Linh V., and Leonid A. Kunyansky. "A Dissipative Time Reversal Technique for Photoacoustic Tomography in a Cavity." SIAM PUBLICATIONS, 2016. http://hdl.handle.net/10150/622000.
Full textDonner, Quentin. "Correction de l'atténuation et du rayonnement diffusé en tomographie d'émission à simples photons." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10155.
Full textThe aim of single photon emission tomography is to compute a functional picture of an organ. This is done by administering to the patient a radiopharmaceutical which is fixing in the organ. Then, one computes the distribution of the radiopharmaceutical from the measurement of the emitted gamma-rays. However, an important part of these gamma-rays are interacting with the matter inside the body. The aim of this work is to take these interactions into account so as to reconstruct more accurately. .
Arhjoul, Lahcen. "Modélisation pharmacocinétique en tomographie d'émission par positrons en utilisant la technique des ondelettes." Thèse, Université de Sherbrooke, 2006. http://savoirs.usherbrooke.ca/handle/11143/4232.
Full text