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Dissertations / Theses on the topic 'Medical Imaging System'
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Ahsan, Syed Naveed. "Design of a microwave tomography system for medical imaging applications." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/design-of-a-microwave-tomography-system-for-medical-imaging-applications(22b1f094-5dec-467d-b646-ad6801d6fbaa).html.
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Microwave tomography (MT) is an emerging imaging modality which aims to recover the dielectric profile of a domain by solving an inverse problem. This is a challenging problem that requires sophisticated algorithms as well as hardware design. This thesis presents a simple and low cost design of a MT system that can operate in the 1-3 GHz frequency range. The hardware prototype of the system is developed from concept to physical realization and is validated against numerical and experimental studies using an in-house inversion algorithm. As with most experimental MT systems presented in the literature, this thesis focuses on cylindrical setups that can be imaged efficiently with a two-dimensional (2-D) inversion algorithm. Using an antenna that can operate efficiently in the desired MT frequency spectrum is essential for any MT system. To this end, the thesis studies several antenna designs and evaluates their performance by calculating return loss and transmission levels in the desired frequency range. Based on this analysis, we select a custom-made printed monopole antenna with very small size which can operate efficiently across the selected frequency range when immersed in various materials that are used as coupling liquids in microwave tomographic systems. The selection of coupling medium is quite vital in the design of a microwave imaging system, which is subject to various signals that obscure the response from the object to be imaged. In particular, multipath signal propagation and surface waves along with other degrading factors such as noise, coupling etc., pose significant challenges to data integrity. We address this issue by studying the performance of the selected antenna (stand-alone and as an array) in various coupling liquids, such as water mixed with glycerine or corn syrup. The aim of this study is to ensure that the sensitivity of our MT system is sufficient to detect weak target responses in a practical measurement with a standard vector network analyzer (VNA), while at the same time effects such as antenna coupling and multi-path propagation are minimised. The thesis also presents a comparison of two possible MT setups: non-immersed con-figuration, where the array of antennas operates in free space but very close to the imaging chamber, and an eight-element antenna array immersed inside different coupling liquids. The array performance in the aforementioned configurations is also experimentally assessed, by acquiring data with a two-port vector network analyser (VNA). In terms of the reconstruction scenarios, we focus on two cases that are studied numerically and experimentally: a target inside a cylinder filled with coupling medium, and the target inside a cylinder filled with a low-loss liquid, surrounded by the coupling liquid where the antennas are immersed. Comparison of our experiments to numerical data suggests that measurements are very sensitive to errors such as cable movements or imprecise spatial positioning of antennas relative to the imaging chamber. To circumvent these issues, we synthesise the array by acquiring data in a bi-static configuration using a robust, mechanically calibrated system which can guarantee accurate antenna positioning. Comparing the measurement data from the bi-static configuration with CST simulation results lead to a much better agreement. This suggests that a significant source of measurement error can be introduced if the multi-static system is not designed with a lot of care on cables positioning. An in-house inversion algorithm is applied to the acquired data to validate our system’s ability to reconstruct cylindrical targets. The cylindrical target is reconstructed successfully using the inversion algorithm with both experimental and simulation data for both imaging scenarios of one and two-layer phantoms. The system is among world’s first experimental imaging systems that can reconstruct targets successfully in the wide frequency range of 1-3 GHz.
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Li, Xiping. "Web-based Medical Imaging Simulation System for Education and Research." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/682.
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In this work, a major effort has been made to establish an Internet accessible system for medical imaging simulation as a convenient service under the cloud computing environment. First, an Internet accessible, medical imaging education platform has been developed. It includes teaching and dynamic assessment tracking system for five commonly used imaging modalities. The system is integrated by the open source MySQL database software that manages updating materials and also tracks students’ learning engagements, which allow the reliability and appropriateness of the on-line teaching material and assessment methods to be optimized. The evaluation results have shown increased learning gains promisingly. Second, a prototype simulation service platform has been established. It is based on a job-oriented work flow to provide different kinds of service to users to perform medical imaging simulation. These simulations not only include the straightforward CT data reconstruction based on Radon transform, but also the sophisticated PET imaging simulation based on GATE as well. The QGATE’s client-server configuration can manage the GATE system to queue and monitor the submitted simulation scripts and return simulation results. The system is suitable for classroom training and easy to use for students or new users to the field of nuclear medicine imaging simulation. Finally, based on the developed simulation platform, a simulation study on PET imaging has been carried out. Event-based dynamic justification method has been tested based on the phantoms generated by NCAT associated with different breathing signals. The results show its potential capability of motion correction for PET data acquisition.
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Wells, Matthew. "An expert system for the visualization of medical image data." Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU053302.
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This work starts from the premise that, given the current considerable growth in medical imaging, there is a need to develop a method that allows the information thus gathered to be used to its optimum - not only as a separate data set but also within the context of other related data. From this has grown the concept of a visualization tool which aids the visual comprehension of data present in an image by using information both internal and external to it. As a result, key medical features should be identified, labelled and presented in a clear and meaningful manner. The development of the visualization tool has been achieved through the use of blackboard-based expert system. As well as providing a method for integrating the different models used, the blackboard shell has enabled all aspects of the visualization process to be centrally supervised using a powerful and flexible control mechanism that permits both goal directed and data driven behaviour within the system. The modular approach that has been applied permits the model-based processes of feature recognition to be developed as quasi-independent systems. Two feature recognition models have been developed and these are interfaced to the rest of the tool through a set of feature dependent experts that contain knowledge about how and when to use these models to their optimum. In addition, further modification to the prototype shell used has permitted the development and application of a feature sensitive search strategy. All components of the visualization tool have been tested separately and as a whole using real medical image data from a relatively low resolution source and have been proved to work. The regions and features information applied proved the viability of the overall-performance of the knowledge based feature models and allowed the results to be visually presented in a concise and original manner that provided additional information to an image without loss of the original information.
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Lee, Michael, and Daniel Doonan. "Resolution Analysis and System Integration of a Dynamically Reconfigurable FMCW Medical Ultrasound Imaging System." International Foundation for Telemetering, 2012. http://hdl.handle.net/10150/581733.
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ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, CaliforniaThis paper describes the system performance analysis of the dynamically reconfigurable FMCW medical ultrasound imaging systems. Full-scale resolution analysis, for mono-static, bi-static, and multi-static data-acquisition formats, and laboratory experiment are included in the analysis.
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Tang, Mei-yee, and 鄧美宜. "Medical imaging: applications of functional magnetic resonance imaging and the development of a magnetic resonancecompatible ultrasound system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37897688.
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Tang, Mei-yee. "Medical imaging : applications of functional magnetic resonance imaging and the development of a magnetic resonance compatible ultrasound system /." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36749710.
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Zhao, Jing. "Design and evaluation of a screen-CCD imaging system for medical radiology /." Online version of thesis, 1992. http://hdl.handle.net/1850/11253.
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Zheng, Wei. "A Web based distributed medical record and imaging entry and visualization system." [Florida] : State University System of Florida, 2000. http://etd.fcla.edu/etd/uf/2000/ana7047/master.PDF.
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Thesis (M.S.)--University of Florida, 2000.Title from first page of PDF file. Document formatted into pages; contains x, 64 p.; also contains graphics. Vita. Includes bibliographical references (p. 62-63).
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Clark, Christopher Alan. "Magnetic resonance techniques for measurement of water diffusion in the human central nervous system." Thesis, University College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286293.
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Lee, Junwon. "The development of a miniature imaging system: Design, fabrication and metrology." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289892.
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The topic of dissertation is on the development of a miniature imaging device named as multi-modal miniature microscope [a.k.a. 4M Device]. Generally speaking, the development of an optical imaging device involves three main processes: optical design, fabrication and metrology. They are interdependent and often comprise a feedback loop. This dissertation will address these three processes sequentially. The 4M device is miniature compound microscope consisting of miniature optics, electronic imaging device, and mechanical device. Every component is integrated on single silicon substrate. The main purpose of 4M device is to provide an imaging capability for the detection of pre-cancer without biopsy. It uses a novel optics called hybrid lens that is fabricated by using a grayscale photomask and photolithographic technique. The hybrid lens is made of sot-gel material and glass substrate. It has 1.2mm of diameter and its surface is conic. Given lens design constraints from the fabrication, the series of lens design for 4M device are implemented and presented. Each design delivers diffraction-limited imaging performance with N.A ranging from 0.4 to 0.7. The 4M device that is currently built has 0.4 of N.A. The imaging quality assessments of 4M device are also implemented in quantitative and qualitative ways. There are two instruments for imaging quality assessment: Multi-modal imaging testbed for entire imaging device and Shack-Hartmann wavefront sensor for individual element. The qualitative assessment includes multi-modal imaging experiments under different illumination modes. The object is a cervical cancer cell prepared by Dr. Kortum's Group at Univ. of Texas at Austin. The qualitative assessment includes the surface characterization and wavefront measurement of individual optics and the MTF measurement of entire device. The results of imaging quality assessment show the potential of 4M device for medical imaging device. They also explain the degradation of imaging quality.
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Sharif, Mhd Saeed. "An artificial intelligent system for oncological volumetric medical PET classification." Thesis, Brunel University, 2013. http://bura.brunel.ac.uk/handle/2438/13095.
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Positron emission tomography (PET) imaging is an emerging medical imaging modality. Due to its high sensitivity and ability to model physiological function, it is effective in identifying active regions that may be associated with different types of tumour. Increasing numbers of patient scans have led to an urgent need for the development of new efficient data analysis system to aid clinicians in the diagnosis of disease and save decent amount of the processing time, as well as the automatic detection of small lesions. In this research, an automated intelligent system for oncological PET volume analysis has been developed. Experimental NEMA (national electrical manufacturers association) IEC (International Electrotechnical Commission) body phantom data set, Zubal anthropomorphic phantom data set with simulated tumours, clinical data set from patient with histologically proven non-small cell lung cancer, and clinical data sets from seven patients with laryngeal squamous cell carcinoma have been utilised in this research. The initial stage of the developed system involves different thresholding approaches, and transforming the processed volumes into the wavelet domain at different levels of decomposition by deploying Haar wavelet transform. K-means approach is also deployed to classify the processed volume into a distinct number of classes. The optimal number of classes for each processed data set has been obtained automatically based on Bayesian information criterion. The second stage of the system involves artificial intelligence approaches including feedforward neural network, adaptive neuro-fuzzy inference system, self organising map, and fuzzy C-means. The best neural network design for PET application has been thoroughly investigated. All the proposed classifiers have been evaluated and tested on the experimental, simulated and clinical data sets. The final stage of the developed system includes the development of new optimised committee machine for PET application and tumour classification. Objective and subjective evaluations have been carried out for all the systems outputs, they show promising results for classifying patient lesions. The new approach results have been compared with all of the results obtained from the investigated classifiers and the developed committee machines. Superior results have been achieved using the new approach. An accuracy of 99.95% is achieved for clinical data set of patient with histologically proven lung tumour, and an average accuracy of 98.11% is achieved for clinical data set of seven patients with laryngeal tumour.
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Marticke, Fanny. "Optimization of an X-ray diffraction imaging system for medical and security applications." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT055/document.
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L’imagerie basée sur la diffraction des rayons X est une technique non-invasive puissante pour l’identification et caractérisation de matériaux différents. Comparée aux techniques traditionnelles utilisant la transmission des rayons X, elle permet d’extraire des informations beaucoup plus caractéristiques pour le matériau inspecté, comme les positions des pics de Bragg pour des matériaux cristallins et le facteur de forme moléculaire pour les matériaux amorphes. Le potentiel de cette méthode a été reconnu par de nombreuses équipes de recherche et de nombreuses applications comme l’inspection de bagage, le contrôle non-destructif, la détection de drogue et la caractérisation de tissus biologiques ont été proposées. La méthode par dispersion d’énergie (EDXRD) est particulièrement adaptée à ce type d’application car elle permet l’utilisation d’un tube à rayons X conventionnel, l’acquisition du spectre entier en une fois et des architectures parallélisées pour l’inspection d’un objet entier en un temps raisonnable. L’objectif de ce travail est d’optimiser toute la chaîne de caractérisation. L’optimisation comprend deux aspects : l’optimisation du système d’acquisition et du traitement des données. La dernière concerne particulièrement la correction des spectres de diffraction dégradés par le processus d’acquisition. Des méthodes de reconstruction sont proposées et validées sur des spectres simulés et expérimentaux. L’optimisation du système est réalisée en utilisant des facteurs de mérite comme l’efficacité quantique de détection (DQE), le rapport contraste sur bruit (CNR) et les courbes de caractéristiques opérationnelles de réception (ROC).La première application choisie, c’est l’imagerie du sein basée sur la diffraction qui a pour but de distinguer des tissus cancéreux des tissus sains. Deux configurations de collimation sans multiplexage combinant EDXRD et ADXRD sont proposées suite au processus d’optimisation. Une étude de simulation du système entier et d’un fantôme de sein a été réalisée afin de déterminer la dose requise pour la détection d’un petit carcinome de 4 mm. La deuxième application concerne la détection de matériaux illicites pendant le contrôle de sécurité. L’intérêt possible d’un système de collimation multiplexé a été étudiéX-ray diffraction imaging is a powerful noninvasive technique to identify or characterize different materials. Compared to traditional techniques using X-ray transmission, it allows to extract more material characteristic information, such as the Bragg peak positions for crystalline materials as well as the molecular form factor for amorphous materials. The potential of this technique has been recognized by many researchers and numerous applications such as luggage inspection, nondestructive testing, drug detection and biological tissue characterization have been proposed.The method of energy dispersive X-ray diffraction (EDXRD) is particularly suited for this type of applications as it allows the use of a conventional X-ray tube, the acquisition of the whole spectrum at the same time and parallelized architectures to inspect an entire object in a reasonable time. The purpose of the present work is to optimize the whole material characterization chain. Optimization comprises two aspects: optimization of the acquisition system and of data processing. The last one concerns especially the correction of diffraction pattern degraded by acquisition process. Reconstruction methods are proposed and validated on simulated and experimental spectra. System optimization is realized using figures of merit such as detective quantum efficiency (DQE), contrast to noise ratio (CNR) and receiver operating characteristic (ROC) curves.The first chosen application is XRD based breast imaging which aims to distinguish cancerous tissues from healthy tissues. Two non-multiplexed collimation configurations combining EDXRD and ADXRD are proposed after optimization procedure. A simulation study of the whole system and a breast phantom was realized to determine the required dose to detect a 4 mm carcinoma nodule. The second application concerns detection of illicit materials during security check. The possible benefit of a multiplexed collimation system was examined
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Vakilna, Yash Shashank. "Novel Approach for Characterizing Properties of Nerve Fiber Bundles in Central Nervous System." Thesis, University of California, Irvine, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10936496.
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Spherical Mean technique (SMT) is a novel method of quantifying the diffusion properties of the nerve fibers bundles in the central nervous system. It does this by calculating the spherical mean of the diffusion signal and fitting it to a parametric equation to obtain per voxel diffusion coefficients. We used Expectation–Maximization to obtain Gaussian Mixture Models (GMM) to find distinct clusters in per voxel coefficient space. We found that the diffusion properties of all the white matter fibers were clustered into a single Gaussian distribution in 867 brain volume samples. This implies that the diffusion properties of the white matter fibers are relatively homogeneous. Then, we checked this result by comparing the clusters obtained using GMM with tissue classification outputs obtained by clustering Fractional Anisotropy (obtained using Diffusion Tensor modeling), T1 weighted image intensity and B0 image intensity for 867 brain volume samples; we observed that the specific clusters of per voxel diffusion coefficients obtained using GMM represent specific tissue types (grey matter fibers, white matter fibers, cerebrospinal fluid). Since the parameters derived from SMT represent the physical diffusion properties that are independent of microscopic fiber orientation and the distribution of diffusion coefficients of white matter can be modeled by a single Gaussian distribution, we can conclude that the diffusion properties of all white matter fiber are homogeneous.
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VERDENELLI, LORENZO. "Innovative 3D-printed gamma-camera collimators for medical imaging." Doctoral thesis, Università Politecnica delle Marche, 2022. http://hdl.handle.net/11566/295563.
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In medicina nucleare, la gamma-camera è uno dei dispositivi di imaging più utilizzati per l'imaging dei radionuclidi. Le gamma-camere sono il cuore di molti dispositivi utilizzati in medicina nucleare che vanno dal sistema scintigrafico al sistema SPECT (Tomografia computerizzata a emissione di singolo fotone). Lo scopo principale di una gamma-camera è fornire al medico informazioni utili in termini di risoluzione spaziale e sensibilità per l’organo sotto indagine. Quindi, partendo da studi precedenti in cui sono state applicate le tecnologie AM (Additive manufacturing) per la realizzazione di collimatori, si è proceduto fornendo un nuovo concetto di collimatore a fori paralleli con forma del foro ottimizzata e con una strategia di fabbricazione completamente innovativa stampando il negativo del collimatore tradizionale. Con "geometria negativa" si intende estrudere i fori, solitamente vuoti, e riempire poi lo spazio tra questi fori con una polvere metallica ad alta densità (es. tungsteno). Applicando questo concetto, abbiamo scoperto di essere in grado di fornire un prodotto completamente personalizzabile e a basso costo utilizzando le tradizionali tecnologie di stampa FDM (modellazione a deposizione fusa) e SLS (sinterizzazione laser selettiva). Sono state stampate in 3D due diverse geometrie, per un totale di sei campioni. Questi campioni sono stati poi riempiti a mano con polvere di tungsteno e sono stati scansionati, mediante scanner CT, al fine di valutare come la polvere fosse dispersa tra i setti. A bordo della stampante FDM è stato anche montato un sistema di imaging utilizzato per acquisire il processo di stampa ed è stato utilizzato per acquisire un'immagine di ogni singolo strato stampato illuminato da tre illuminatori a linea laser, che lavorano nella gamma di 630 nm (illuminatori rossi). Gli illuminatori laser sono stati posizionati per fornire le condizioni di illuminazione migliori e costanti sullo strato sottoposto ad imaging. Le immagini sono state post-elaborate e utilizzate per ricreare un modello 3D della parte stampata da utilizzare poi nel software di simulazione GATE. È stata condotta un'analisi numerica, basata sul toolkit GATE Monte Carlo, per simulare i collimatori di riferimento e concetti innovativi. Le simulazioni sono state effettuate utilizzando diversi radioisotopi (Tc99, Lu177, In111 e Ga67) e materiali (Tungsteno, PLA e PA2200). Sperimentalmente, il campione è stato testato principalmente con la sorgente Tc99m, per confermare la validità dell'idea proposta. I risultati dell'analisi numerica mostrano un comportamento simile per quanto riguarda la risoluzione spaziale con i rispettivi collimatori di riferimento, mentre per la sensibilità si riporta una riduzione che va dal 45% fino all'80% delle entries. Ciò è dovuto principalmente al pixel estruso, realizzato in PLA o PA2200, avente densità maggiore (~1,24 g/cc per PLA e ~0,95 g/cc per PA2200) rispetto all'aria (~0,0012 g/cc) . Anche il modello ricostruito in 3D utilizzando il sistema di imaging è stato valutato numericamente. Dimostrando che gli errori del processo additivo, come non linearità e non parallelismo tra i fori estrusi, possono avere un effetto peggiorativo sulle prestazioni del sistema. Per applicazioni future sono necessarie ulteriori implementazioni, specialmente per quanto riguarda la procedura di riempimento che deve essere migliorata per raggiungere una maggiore percentuale di polvere depositata.In nuclear medicine, the gamma-camera is one of the most used imaging devices for radionuclide imaging. Gamma-cameras are the key point of many devices used in nuclear medicine ranging from the scintigraphic system to SPECT (Single photon emission computed tomography) system. The main aim of a gamma-camera is to provide to the physician useful information in terms of spatial resolution and sensitivity of the organ under investigation. So, starting from previous studies where the AM (Additive manufacturing) technologies have been applied for the realization of collimators, we proceeded providing a novel concept of a parallel hole collimator with optimized hole shape and with a completely novel fabrication strategy printing the negative of the traditional collimator. With "negative geometry" we mean extruding the holes, usually empty, and filling then the space between these holes with a high dense metal powder (eg. Tungsten). Applying this concept, we found to be able to provide a fully customizable and low-cost product using traditional FDM (Fused deposition modeling) and SLS (Selective laser sintering) printing technologies. Two different geometries, for a total of six samples, have been 3D printed. These samples have been then filled by hand-filling process with tungsten powder and have been scanned, using CT scanner, in order to evaluate how the powder is dispersed between the septa. An imaging system used to acquire the printing process has been also mounted on-board of the FDM printer and it has been used to acquire a picture of each printed layer while being illuminated by three laser-line illuminators working in the 630 nm range (red illuminators). Laser illuminators have been placed to provide the best and constant illumination conditions on the imaged layer. Images have been post-processed and used to recreate a 3D model of the printed part to be then used in the simulation software GATE. A numerical analysis, based on GATE Monte Carlo toolkit, has been conducted to simulate the reference and the innovative concepts collimators. The simulations have been done using different radio-isotopes (Tc99, Lu177, In111 and Ga67) and materials (Tungsten, PLA and PA2200). Experimentally, the sample have been proved, mostly with the Tc99m source, to confirm the validity of the proposed idea. Results of the numerical analysis show a similar behavior for what concern the spatial resolution with the respective reference collimators, while for the sensitivity a reduction that range from 45% up to 80% of entries is reported. This is due mainly to the extruded pixel, made of PLA or PA2200, having higher density (~1.24 g/cc for PLA and ~0,95 g/cc for PA2200) with respect to air (~0,0012 g/cc). The 3D reconstructed model using the imaging system has been numerically evaluated as well. Demonstrating that the additive process errors, such as non-linearity and non-parallelism between the extruded holes, can have a worsening effect on the system performance. For future application further implementations are needed, especially for what concern the filling procedure that must be improved in order to reach an higher percentage of filled powder.
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Moura, Lincoln de Assis. "A system for the reconstruction, handling and display of three-dimensional medical structures." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47192.
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Snell, Rodney James 1965. "A digital-electronic video-rate reconstruction system for magnetic resonance imaging." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278071.
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A digital-electronic video-rate reconstruction system for Magnetic Resonance Imaging (MRI) has been designed to first order. The maturation of ultra-fast acquisition techniques in MRI has produced the need for a reconstruction system that will enable dynamic processes to be viewed on-line. Conventional reconstruction hardware is not configured for real-time reconstruction and previous developments are limited in accuracy and flexibility. The real-time reconstruction system presented here consists of three main subsystems. A digitizer interfaces with an MR scanner to digitize data matrices of resolutions up to 256 x 256 at arbitrary rates up to video rates. A Fourier processor performs either 2D Fourier transformation or projection filtering on the digitized data at video-rates. A backprojector performs the backprojection operation on filtered-projection data at video-rates. The complete system would be able to reconstruct data acquired from nearly any acquisition technique. True real-time MRI is then possible.
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Kardan, Ahmad A. "An ultrasonic system for intravascular measurement and visualisation of anatomical structures and blood flow." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46857.
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Archwamety, Charnchai. "Design and simulation of a totally digital image system for medical image applications." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184294.
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The Totally Digital Imaging System (TDIS) is based on system requirements information from the Radiology Department, University of Arizona Health Science Center. This dissertation presents the design of this complex system, the TDIS specification, the system performance requirements, and the evaluation of the system using the computer simulation programs. Discrete event simulation models were developed for the TDIS subsystems, including an image network, imaging equipment, storage migration algorithm, data base archive system, and a control and management network. The simulation system uses empirical data generation and retrieval rates measured at the University Medical Center hospital. The entire TDIS system was simulated in Simscript II.5 using a VAX 8600 computer system. Simulation results show the fiber optical image network to be suitable, however, the optical disk storage system represents a performance bottleneck.
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Edge, Jonathan Culmer. "Design and development of a system for three dimensional periodontal probing measurement." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322066.
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Lee, Jong-Ha. "Tactile sensation imaging system and algorithms for tumor detection." Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/151945.
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Electrical EngineeringPh.D.
Diagnosing early formation of tumors or lumps, particularly those caused by cancer, has been a challenging problem. To help physicians detect tumors more efficiently, various imaging techniques with different imaging modalities such as computer tomography, ultrasonic imaging, nuclear magnetic resonance imaging, and mammography, have been developed. However, each of these techniques has limitations, including exposure to radiation, excessive costs, and complexity of machinery. Tissue elasticity is an important indicator of tissue health, with increased stiffness pointing to an increased risk of cancer. In addition to increased tissue elasticity, geometric parameters such as size of a tissue inclusion are also important factors in assessing the tumor. The combined knowledge of tissue elasticity and its geometry would aid in tumor identification. In this research, we present a tactile sensation imaging system (TSIS) and algorithms which can be used for practical medical diagnostic experiments for measuring stiffness and geometry of tissue inclusion. The TSIS incorporates an optical waveguide sensing probe unit, a light source unit, a camera unit, and a computer unit. The optical method of total internal reflection phenomenon in an optical waveguide is adapted for the tactile sensation imaging principle. The light sources are attached along the edges of the waveguide and illuminates at a critical angle to totally reflect the light within the waveguide. Once the waveguide is deformed due to the stiff object, it causes the trapped light to change the critical angle and diffuse outside the waveguide. The scattered light is captured by a camera. To estimate various target parameters, we develop the tactile data processing algorithm for the target elasticity measurement via direct contact. This algorithm is accomplished by adopting a new non-rigid point matching algorithm called "topology preserving relaxation labeling (TPRL)." Using this algorithm, a series of tactile data is registered and strain information is calculated. The stress information is measured through the summation of pixel values of the tactile data. The stress and strain measurements are used to estimate the elasticity of the touched object. This method is validated by commercial soft polymer samples with a known Young's modulus. The experimental results show that using the TSIS and its algorithm, the elasticity of the touched object is estimated within 5.38% relative estimation error. We also develop a tissue inclusion parameter estimation method via indirect contact for the characterization of tissue inclusion. This method includes developing a forward algorithm and an inversion algorithm. The finite element modeling (FEM) based forward algorithm is designed to comprehensively predict the tactile data based on the parameters of an inclusion in the soft tissue. This algorithm is then used to develop an artificial neural network (ANN) based inversion algorithm for extracting various characteristics of tissue inclusions, such as size, depth, and Young's modulus. The estimation method is then validated by using realistic tissue phantoms with stiff inclusions. The experimental results show that the minimum relative estimation errors for the tissue inclusion size, depth, and hardness are 0.75%, 6.25%, and 17.03%, respectively. The work presented in this dissertation is the initial step towards early detection of malignant breast tumors.
Temple University--Theses
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Colak, Evrim I. "An Improved Data Acquisition System For Contactless Conductivity Imaging." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606521/index.pdf.
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The previous data acquisiton system developed for the electrical impedance imaging
via contactless measurements is improved to obtain measurements with a faster
scanning speed of 0.15 sec/mm2. This system uses magnetic excitation to induce
currents inside the body and measures the magnetic fields of the induced currents
with an axial gradiometer. Gradiometer consists of two differentially connected
10000-turn coils with diameter of 30 mm and a transmitter coil of 100-turn coil of
diameter 30 mm placed and magnetically coupled between them. Transmitter coil is
driven by a sinusoidal current of 200 mA (peak) whose frequency is 14.1 kHz. A
Data Acquisition Card (DAcC) is designed and constructed on PCB, thus elliminates
the use of the Lock-In Amplifier Instrument (LIAI) in the phase sensitive
measurements. User interface programs to control the scanning experiments via PC
(MATLAB Scanner 1.0, HP VEE Scanner 1.0) and to analyze the acquired data
(Data Observer 1.0) are prepared. System performance tests for the DAcC are made.
Error in the phase sensitive measurements is measured to be 0.6% of the test signals.
Minimum magnetic field density that can be detected is found to be 7 DT. Output
stage performance of the DAcC is improved by using an integrator instead of an
amplifier in the output stage. In this manner, maximum linearity error is measured as
6.60*10-4 % of the full scale for the integrator circuit. Thermally generated voltage
drift at the sensor output is measured to be 0.5 mV/minute in the ambient
temperature. Overall normalized standard deviation at the output of the data
acquisition system is observed as to be in the order of 10-4. Mathematical relation
between the resistive rings and conductive phantoms is studied. It is derived that
maximum resistor value that can be distinguished in the resistive ring experiment
which is 461 F, corresponds to the phantom conductivity of 2.7 S/m. Field profiles
(i.e., the voltage measurements) for the human left hand is obtained for the first time
in literature, employing the LIAI. Agar objects with conductivity value of 1 S/m in a
saline solution of 0.2 S/m are scanned and the field profiles are obtained using the
DAcC. Image profiles of the scan fit well with the actual locations, geometries, and
relative dimensions of the agar objects. A coil winding machine is prepared which
enables the operator to design and wind up coils under self-controlled environment
and conditions.
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Fares, Ali F. "Volume measurements of human upper-arm muscles using compounded ultrasound imaging system." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179510154.
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Almotiri, Jasem. "A Multi-Anatomical Retinal Structure Segmentation System for Automatic Eye Screening Using Morphological Adaptive Fuzzy Thresholding." Thesis, University of Bridgeport, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10975223.
Full textAbstract:
Eye exam can be as efficacious as physical one in determining health concerns. Retina screening can be the very first clue to detecting a variety of hidden health issues including pre-diabetes and diabetes. Through the process of clinical diagnosis and prognosis; ophthalmologists rely heavily on the binary segmented version of retina fundus image; where the accuracy of segmented vessels, optic disc and abnormal lesions extremely affects the diagnosis accuracy which in turn affect the subsequent clinical treatment steps. This thesis proposes an automated retinal fundus image segmentation system composed of three segmentation subsystems follow same core segmentation algorithm. Despite of broad difference in features and characteristics; retinal vessels, optic disc and exudate lesions are extracted by each subsystem without the need for texture analysis or synthesis. For sake of compact diagnosis and complete clinical insight, our proposed system can detect these anatomical structures in one session with high accuracy even in pathological retina images.
The proposed system uses a robust hybrid segmentation algorithm combines adaptive fuzzy thresholding and mathematical morphology. The proposed system is validated using four benchmark datasets: DRIVE and STARE (vessels), DRISHTI-GS (optic disc), and DIARETDB1 (exudates lesions). Competitive segmentation performance is achieved, outperforming a variety of up-to-date systems and demonstrating the capacity to deal with other heterogenous anatomical structures.
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Bravaglieri, Lisa. "ClinQC: quality control of an X-ray imaging system using clinical images." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/12172/.
Full textAbstract:
The work presented in this thesis is part of a research project of Leiden University Medical Center (LUMC) in The Netherlands. It belongs to the field of Diagnostic Radiology analysed from a Medical Physics point of view. After a short overview of the weekly quality controls of an X-ray imaging device, performed using simple phantoms, the thesis focuses on a novel approach called ClinQC (Clinical images-based Quality Control): it has the purpose to monitor the stability of imaging devices, aiming at the early detection of changes in image quality or radiation dose, by deriving quality parameters from chest images of routine patient examinations. The ClinQC algorithm extracts the noise from clinical images and derives the main dose quantities. The noise study presented in this thesis comprehends a validation of the algorithm, performed in several ways: image deteriorations, simulations, phantom studies and real clinical examples. For dose and homogeneity studies only some preliminary results are presented. The thesis collects also some ideas of improvement that can be considered for the future versions of the algorithm and to extend the ClinQC project to other X-ray anatomies and imaging modalities.
The obtained similar results for the two compared methods prove that ClinQC is able to give immediate feedbacks of the quality of the imaging devices using patient images. It provides reliable, on-the-fly and sensitive parameters of the quality of the X-ray imaging system, that have the same physical meaning and similar relative variation as the quality indicators of the gold standard QClight method. It can be concluded that the ClinQC algorithm could be already applied in clinical practice, with the initial support of the QClight weekly quality control. In this way, a comparison between the two methods in a real test period will be a guide to find the necessary adjustments of the algorithm until the final version is being installed and stably used in clinical practice.
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Rostrom, Timothy James. "Framework to Secure Cloud-based Medical Image Storage and Management System Communications." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/3124.
Full textAbstract:
Picture Archiving and Communication Systems (PACS) have been traditionally constrained to the premises of the healthcare provider. This has limited the availability of these systems in many parts of the world and mandated major costs in infrastructure for those who employ them. Public cloud services could be a solution that eases the cost of ownership and provides greater flexibility for PACS implementations. This could make it possible to bring medical imaging services to places where it was previously unavailable and reduce the costs associated with these services for those who utilize them. Moving these systems to public cloud infrastructure requires that an authentication and encryption policy for communications is established within the PACS environment to mitigate the risks incurred by using the Internet for the communication of medical data. This thesis proposes a framework which can be used to create an authenticated and encrypted channel to secure the communications with a cloud-based PACS. This framework uses the Transport Layer Security (TLS) protocol and X.509 certificates to create a secured channel. An enterprise style PKI is used to provide a trust model to authorize endpoints to access the system. The validity of this framework was tested by creating a prototype cloud-based PACS with secured communications. Using this framework will provide a system based on trusted industry standards which will protect the confidentiality and integrity of medical data in transit when using a cloud-based PACS service.
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Cros, Olivier. "Image Analysis and Visualization of the Human Mastoid Air Cell System." Licentiate thesis, Linköpings universitet, Medicinsk informatik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-122179.
Full textAbstract:
From an engineering background, it is often believed that the human anatomy has already been fully described. Radiology has greatly contributed to understand the inside of the human body without surgical intervention. Despite great advances in clinical CT scanning, image quality is still related to a limited amount X-ray exposure for the patient safety. This limitation prevents fine anatomical structures to be visible and, more importantly, to be detected. Where such modality is of great advantage for screening patients, extracting parameters like surface area and volume implies the bone structure to be large enough in relation to the scan resolution. The mastoid, located in the temporal bone, houses an air cell system whose cells have a variation in size that can go far below current conventional clinical CT scanner resolution. Therefore, the mastoid air cell system is only partially represented on a CT scan. Any statistical analysis will be biased towards air cells of smaller size. To allow a complete representation of the mastoid air cell system, a micro-CT scanner is more adequate. Micro-CT scanning uses approximately the same amount of X-rays but for a much longer exposure time compared to what is normally allowed for patients. Human temporal bone specimens are therefore necessary when using such scanning method. Where the conventional clinical CT scanner lacks level of minutes details, micro-CT scanning provides an overwhelming amount of fine details. Prior to any image analysis of medical data, visualization of the data is often needed to learn how to extract the structures of interest for further processing. Visualization of micro-CT scans is of no exception. Due to the high resolution nature of the data, visualization of such data not only requires modern and powerful computers, but also necessitates a tremendous amount of time to adjust the hiding of irrelevant structures, to find the correct orientation, while emphasising the structure of interest. Once the quality of the data has been assessed, and a strategy for the image processing has been decided, the image processing can start, to in turn extract metrics such as the surface area or volume and draw statistics from it. The temporal bone being one of the most complex in the human body, visualization of micro-CT scanning of this bone awakens the curiosity of the experimenter, especially with the correct visualization settings. This thesis first presents a statistical analysis determining the surface area to volume ratio of the mastoid air cell system of human temporal bone, from micro-CT scanning using methods previously applied for conventional clinical CT scannings. The study compared current resul s with previous studies, with successive downsampling the data down to a resolution found in conventional clinical CT scanning. The results from the statistical analysis showed that all the small mastoid air cells, that cannot be detected in conventional clinical CT scans, do heavily contribute to the estimation of the surface area, and in consequence to the estimation of the surface area to volume ratio by a factor of about 2.6. Such a result further strengthens the idea of the mastoid to play an active role in pressure regulation and gas exchange. Discovery of micro-channels through specific use of a non-traditional transfer function was then reported, where a qualitative and a quantitative preanalysis was performed are described. To gain more knowledge about these micro-channels, a local structure tensor analysis was applied where structures are described in terms of planar, tubular, or isotropic structures. The results from this structural tensor analysis, also reported in this thesis, suggest these micro-channels to potentially be part of a more complex framework, which hypothetically would provide a separate blood supply for the mucosa lining the mastoid air cell system.
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Nie, Yali. "Automatic Melanoma Diagnosis in Dermoscopic Imaging Base on Deep Learning System." Licentiate thesis, Mittuniversitetet, Institutionen för elektronikkonstruktion, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-41751.
Full textAbstract:
Melanoma is one of the deadliest forms of cancer. Unfortunately, its incidence rates have been increasing all over the world. One of the techniques used by dermatologists to diagnose melanomas is an imaging modality called dermoscopy. The skin lesion is inspected using a magnification device and a light source. This technique makes it possible for the dermatologist to observe subcutaneous structures that would be invisible otherwise. However, the use of dermoscopy is not straightforward, requiring years of practice. Moreover, the diagnosis is many times subjective and challenging to reproduce. Therefore, it is necessary to develop automatic methods that will help dermatologists provide more reliable diagnoses. Since this cancer is visible on the skin, it is potentially detectable at a very early stage when it is curable. Recent developments have converged to make fully automatic early melanoma detection a real possibility. First, the advent of dermoscopy has enabled a dramatic boost in the clinical diagnostic ability to the point that it can detect melanoma in the clinic at the earliest stages. This technology’s global adoption has allowed the accumulation of extensive collections of dermoscopy images. The development of advanced technologies in image processing and machine learning has given us the ability to distinguish malignant melanoma from the many benign mimics that require no biopsy. These new technologies should allow earlier detection of melanoma and reduce a large number of unnecessary and costly biopsy procedures. Although some of the new systems reported for these technologies have shown promise in preliminary trials, a widespread implementation must await further technical progress in accuracy and reproducibility. This thesis provides an overview of our deep learning (DL) based methods used in the diagnosis of melanoma in dermoscopy images. First, we introduce the background. Then, this paper gives a brief overview of the state-of-art article on melanoma interpret. After that, a review is provided on the deep learning models for melanoma image analysis and the main popular techniques to improve the diagnose performance. We also made a summary of our research results. Finally, we discuss the challenges and opportunities for automating melanocytic skin lesions’ diagnostic procedures. We end with an overview of a conclusion and directions for the following research plan.
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DeHoog, Edward Allen. "Novel Fundus Camera Design." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195633.
Full textAbstract:
A fundus camera a complex optical system that makes use of the principle of reflex free indirect ophthalmoscopy to image the retina. Despite being in existence as early as 1900's, little has changed in the design of a fundus camera and there is minimal information about the design principles utilized. Parameters and specifications involved in the design of fundus camera are determined and their affect on system performance are discussed. Fundus cameras incorporating different design methods are modeled and a performance evaluation based on design parameters is used to determine the effectiveness of each design strategy. By determining the design principles involved in the fundus camera, new cameras can be designed to include specific imaging modalities such as optical coherence tomography, imaging spectroscopy and imaging polarimetry to gather additional information about properties and structure of the retina. Design principles utilized to incorporate such modalities into fundus camera systems are discussed. Design, implementation and testing of a snapshot polarimeter fundus camera are demonstrated.
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Tillery, Laura Suzanne. "Managing technological change in a military treatment facility : a case study of medical diagnostic imaging support (MDIS) system /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA294894.
Full textAbstract:
Thesis (M.S. in Information Technology Management) Naval Postgraduate School, December 1994.Thesis advisor(s): Sterling D. Sessions. "December 1994." Bibliography: p. 100-103. Also available online.
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Bathini, Praneeth. "EXPLOITATION OF THE IMAGE CHARACTERISTICS OF A LOCALIZED TRANSILLUMINATION SYSTEM UTILIZING MOLECULAR CONTRAST AGENTS AND POLARIMETRY." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1201198204.
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Ku, Geng. "Photoacoustic and thermoacoustic tomography: system development for biomedical applications." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3181.
Full textAbstract:
Photoacoustic tomography (PAT), as well as thermoacoustic tomography (TAT),
utilize electromagnetic radiation in its visible, near infrared, microwave, and
radiofrequency forms, respectively, to induce acoustic waves in biological tissues for
imaging purposes. Combining the advantages of both the high image contrast that results
from electromagnetic absorption and the high resolution of ultrasound imaging, these
new imaging modalities could be the next successful imaging techniques in biomedical
applications. Basic research on PAT and TAT, and the relevant physics, is presented in
Chapter I. In Chapter II, we investigate the imaging mechanisms of TAT in terms of
signal generation, propagation and detection. We present a theoretical analysis as well as
simulations of such imaging characteristics as contrast and resolution, accompanied by
experimental results from phantom and tissue samples. In Chapter III, we discuss the
further application of TAT to the imaging of biological tissues. The microwave
absorption difference in normal and cancerous breast tissues, as well as its influence on
thermoacoustic wave generation and the resulting transducer response, is investigated
over a wide range of electromagnetic frequencies and depths of tumor locations. In
Chapter IV, we describe the mechanism of PAT and the algorithm used for image
reconstruction. Because of the broad bandwidth of the laser-induced ultrasonic waves and
the limited bandwidth of the single transducer, multiple ultrasonic transducers, each with
a different central frequency, are employed for simultaneous detection. Chapter V further
demonstrates PATÂs ability to image vascular structures in biological tissue based on
bloodÂs strong light absorption capability. The photoacoustic images of rat brain tumors
in this study clearly reveal the angiogenesis that is associated with tumors. In Chapter
VI, we report on further developing PAT to image deeply embedded optical
heterogeneity in biological tissues. The improved imaging ability is attributed to better
penetration by NIR light, the use of the optical contrast agent ICG (indocyanine green)
and a new detection scheme of a circular scanning configuration. Deep penetrating PAT,
which is based on a tissueÂs intrinsic contrast using laser light of 532 nm green light and
1.06 µm near infrared light, is also presented.
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Bai, Yu. "Characterization of an Adaptive Optics System for Vision Studies." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1461796856.
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Thapa, Bishnu Bahadur. "DEVELOPMENT OF A PATIENT SPECIFIC IMAGE PLANNING SYSTEM FOR RADIATION THERAPY." UKnowledge, 2013. http://uknowledge.uky.edu/physastron_etds/11.
Full textAbstract:
A patient specific image planning system (IPS) was developed that can be used to assist in kV imaging technique selection during localization for radiotherapy. The IPS algorithm performs a divergent ray-trace through a three dimensional computed tomography (CT) data set. Energy-specific attenuation through each voxel of the CT data set is calculated and imaging detector response is integrated into the algorithm to determine the absolute values of pixel intensity and image contrast. Phantom testing demonstrated that image contrast resulting from under exposure, over exposure as well as a contrast plateau can be predicted by use of a prospective image planning algorithm. Phantom data suggest the potential for reducing imaging dose by selecting a high kVp without loss of image contrast. In the clinic, image acquisition parameters can be predicted using the IPS that reduce patient dose without loss of useful image contrast.
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Akcay, Avni Ceyhun. "System design and optimization of optical coherence tomography." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3586.
Full textAbstract:
Optical coherence imaging, including tomography (OCT) and microscopy (OCM), has been a growing research field in biomedical optical imaging in the last decade. In this imaging modality, a broadband light source, thus of short temporal coherence length, is used to perform imaging via interferometry. A challenge in optical coherence imaging, as in any imaging system towards biomedical diagnosis, is the quantification of image quality and optimization of the system components, both a primary focus of this research. We concentrated our efforts on the optimization of the imaging system from two main standpoints: axial point spread function (PSF) and practical steps towards compact low-cost solutions. Up to recently, the criteria for the quality of a system was based on speed of imaging, sensitivity, and particularly axial resolution estimated solely from the full-width at half-maximum (FWHM) of the axial PSF with the common practice of assuming a Gaussian source power spectrum. As part of our work to quantify axial resolution we first brought forth two more metrics unlike FWHM, which accounted for side lobes in the axial PSF caused by irregularities in the shape of the source power spectrum, such as spectral dips. Subsequently, we presented a method where the axial PSF was significantly optimized by suppressing the side lobes occurring because of the irregular shape of the source power spectrum. The optimization was performed through optically shaping the source power spectrum via a programmable spectral shaper, which consequentially led to suppression of spurious structures in the images of a layered specimen. The superiority of the demonstrated approach was in performing reshaping before imaging, thus eliminating the need for post-data acquisition digital signal processing. Importantly, towards the optimization and objective image quality assessment in optical coherence imaging, the impact of source spectral shaping was further analyzed in a task-based assessment method based on statistical decision theory. Two classification tasks, a signal-detection task and a resolution task, were investigated. Results showed that reshaping the source power spectrum was a benefit essentially to the resolution task, as opposed to both the detection and resolution tasks, and the importance of the specimen local variations in index of refraction on the resolution task was demonstrated. Finally, towards the optimization of OCT and OCM for use in clinical settings, we analyzed the detection electronics stage, which is a crucial component of the system that is designed to capture extremely weak interferometric signals in biomedical and biological imaging applications. We designed and tested detection electronics to achieve a compact and low-cost solution for portable imaging units and demonstrated that the design provided an equivalent performance to the commercial lock-in amplifier considering the system sensitivity obtained with both detection schemes.Ph.D.
Optics and Photonics
Optics
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Leal, Michael J. "Effect of pixel size and scintillator on image quality of a CCD-based digital x-ray imaging system." Link to electronic thesis, 2001. http://www.wpi.edu/Pubs/ETD/Available/etd-0502101-123456.
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Liu, Kaiqiang. "Preliminary Development of a Multi-link Modular Robotic System for Improvement of Colonoscopy Intubation Process." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1430756935.
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Nishino, Hiroto. "Real-time Navigation for Liver Surgery Using Projection Mapping With Indocyanine Green Fluorescence: Development of the Novel Medical Imaging Projection System." Kyoto University, 2019. http://hdl.handle.net/2433/242358.
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Nilsson, Erik. "Super-Resolution for Fast Multi-Contrast Magnetic Resonance Imaging." Thesis, Umeå universitet, Institutionen för fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-160808.
Full textAbstract:
There are many clinical situations where magnetic resonance imaging (MRI) is preferable over other imaging modalities, while the major disadvantage is the relatively long scan time. Due to limited resources, this means that not all patients can be offered an MRI scan, even though it could provide crucial information. It can even be deemed unsafe for a critically ill patient to undergo the examination. In MRI, there is a trade-off between resolution, signal-to-noise ratio (SNR) and the time spent gathering data. When time is of utmost importance, we seek other methods to increase the resolution while preserving SNR and imaging time. In this work, I have studied one of the most promising methods for this task. Namely, constructing super-resolution algorithms to learn the mapping from a low resolution image to a high resolution image using convolutional neural networks. More specifically, I constructed networks capable of transferring high frequency (HF) content, responsible for details in an image, from one kind of image to another. In this context, contrast or weight is used to describe what kind of image we look at. This work only explores the possibility of transferring HF content from T1-weighted images, which can be obtained quite quickly, to T2-weighted images, which would take much longer for similar quality. By doing so, the hope is to contribute to increased efficacy of MRI, and reduce the problems associated with the long scan times. At first, a relatively simple network was implemented to show that transferring HF content between contrasts is possible, as a proof of concept. Next, a much more complex network was proposed, to successfully increase the resolution of MR images better than the commonly used bicubic interpolation method. This is a conclusion drawn from a test where 12 participants were asked to rate the two methods (p=0.0016) Both visual comparisons and quality measures, such as PSNR and SSIM, indicate that the proposed network outperforms a similar network that only utilizes images of one contrast. This suggests that HF content was successfully transferred between images of different contrasts, which improves the reconstruction process. Thus, it could be argued that the proposed multi-contrast model could decrease scan time even further than what its single-contrast counterpart would. Hence, this way of performing multi-contrast super-resolution has the potential to increase the efficacy of MRI.
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Wu, Bangxian, and 吴邦限. "Clinical applications of imaging informatics: computer aided diagnosis of nasopharyngeal carcinoma based on PET-CTand multimedia electronic patient record system for neurosurgery." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48521917.
Full textAbstract:
Medical imaging informatics is one of the important research areas in radiology that studies how information available on medical images is retrieved, analyzed, and enhanced. Recent development in medical imaging informatics has resulted in improvement of diagnostic accuracy based on imaging examinations, as well as efficiency in clinical workflow. Computer aided diagnosis (CAD) and electronic patient record system (ePR) are both topics in medical imaging informatics that have matured from research concepts into commercially available computerized systems in clinical environment. The current challenges are to further broaden their scope of applications. In this thesis project, I developed a CAD system for interpreting PET/CT examinations and an ePR system for patient data integration in neurosurgery suites.
Specifically, the CAD system in this project was designed to automatically diagnose nasopharyngeal carcinoma (NPC) on Positron emission tomography/computed tomography (PET/CT) examinations, which aimed to detect and classify both the primary NPC and its nodal metastasis. The regions of interests (ROIs) were segmented from the PET images and registered onto the CT in order to combine the imaging features from both modalities and the a priori anatomical knowledge of the suspicious lesion. These combined features were then classified by a support vector machine (SVM) to generate the final diagnosis result. The system was validated with 25 PET/CT examinations from 10 patients suffering from NPC, and the result produced by the system was compared to the gold standard of lesions manually contoured by experienced radiologists. The results confirmed that the system successfully distinguished all 53 genuine lesions from the mimickers due to normal physiological uptake and artifacts that also produced potentially confusing signals.
The second part of the project involved development of an electronic patient record system (ePR) that integrated all the myriad of images and different types of clinical information before, during, and after neurosurgery operations, in order to enhance efficiency of work flow in this unique clinical environment. The system comprises of pre-, intra-, and post-operation modules which correspond to the different stages of the neurosurgery. The pre-op module was developed to store and categorize all images and data before the procedure to assist the surgeons in planning operation. The intra-op module integrates all the input signals, waveforms, images and videos that are produced by different imaging and physiological monitoring devices in the operation room during the surgery, and displays all the relevant information in a single large screen in real time to ease monitoring of the procedure. The post-op module helps surgeons to review all the data acquired from all the prior stages for follow-up of the treatment outcome. One-tumor case was utilized to test the pre-op module, and the signals and waveforms simulators were used to evaluate the performance of the intra-op module.
In summary, two different medical informatics systems, a CAD and an ePR system were developed. Both showed promising results in laboratory tests. Future work would involve performance enhancement and feedback of the systems, and ultimately evaluation of these systems in the clinical environment.published_or_final_version
Diagnostic Radiology
Master
Master of Philosophy
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Guerrero, Julian. "System for vessel characterization : development and evaluation with application to deep vein thrombosis diagnosis." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1558.
Full textAbstract:
A system for vessel characterization aimed at detecting deep vein thrombosis (DVT) in the lower limbs has been developed and evaluated using ultrasound image processing, location and force sensors measurements, blood flow information and a protocol based on the current clinical standard, compression ultrasound. The goal is to provide an objective and repeatable system to measure DVT in a rapid and standardized manner, as this has been suggested in the literature as an approach to improve overall detection of the disease.
The system uses a spatial Kalman filter-based algorithm with an elliptical model in the measurement equation to detect vessel contours in transverse ultrasound images and estimate ellipse parameters, and temporal constant velocity Kalman filters for tracking vessel location in real-time. The vessel characterization also comprises building a 3-D vessel model and performing compression and blood flow assessments to calculate measures that indicate the possibility of DVT in a vessel. A user interface designed for assessing a vessel for DVT was also developed.
The system and components were implemented and tested in simulations, laboratory settings, and clinical settings. Contour detection results are good, with mean and rms errors ranging from 1.47-3.64 and 3.69-9.67 pixels, respectively, in simulated and patient images, and parameter estimation errors of 5%. Experiments showed errors of 3-5 pixels for the tracking approaches. The measures for DVT were evaluated, independently and integrated in the system. The complete system was evaluated, with sensitivity of 67-100% and specificity of 50-89.5%. System learnability and memorability were evaluated in a separate user study, with good results.
Contributions include a segmentation approach using a full parameter ellipse model in an extended Kalman filter, incorporating multiple measurements, an alternate sampling method for faster parameter convergence and application-specific initialization, and a tracking approach that includes a sub-sampled sum of absolutes similarity calculation and a method to detect vessel bifurcations using flow data. Further contributions include an integrated system for DVT detection that can combine ultrasound B-mode, colour flow and elastography images for vessel characterization, a system interface design focusing on usability that was evaluated with medical professionals, and system evaluations through multiple patient studies.
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Poon, Chien Sing. "Early Assessment of Burn Severity in Human Tissue with Multi-Wavelength Spatial Frequency Domain Imaging." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1484582176416423.
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Ullman, Gustaf. "Quantifying image quality in diagnostic radiology using simulation of the imaging system and model observers." Doctoral thesis, Linköping : Department of Medicine and Health, Linköping University, 2008. http://www.bibl.liu.se/liupubl/disp/disp2008/med1050s.pdf.
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Schmitt, Benjamin A. "Utility of a Volume-Regulated Drive System for Direct Mechanical Ventricular Actuation." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1389634127.
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Di, Sopra Lorenzo. "Geometric Misalignment Calibration and Detector Lag Effect Artifact Correction in a Cone-Beam Flat Panel micro-CT System for Small Animal Imaging." Thesis, KTH, Skolan för teknik och hälsa (STH), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-179873.
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The cone-beam flat panel micro-CT is a high definition imaging system. It acquires projections of an object or animal to reconstruct a 3D image of its internal structure. The device is basically composed by a radiation tube and a detector panel, which are fixed to a gantry that rotates all around the test subject. The micro-CT system is affected by several imperfections and problems, that might lead to serious artifacts that deteriorate the quality of the reconstructed image. In particular, two issues have been discussed in the present work: the source-panel geometric misalignment and the detector lag effect. The first problem concerns the consequences of systems where the different elements are not perfectly aligned to each other. The second issue regards the residual signal, left in the detector's sensor after a projection acquisition, which affects the following frames with ghost images. Both these arguments have been investigated to describe their characteristics and behaviour in a typical acquisition protocol. Then two correction methods have been presented and tested on a real micro-CT device to verify their effectiveness in the artifacts compensation. In the end, a comparison between images before and after the corrections is provided and future prospects are discussed.
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Grevillot, Loïc. "Monte Carlo simulation of active scanning proton therapy system with Gate/Geant4 : Towards a better patient dose quality assurance." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00735746.
Full textAbstract:
Hadron Therapy is an advanced radiotherapy technique for cancer treatment. It offers a better irradiation ballistic than conventional techniques and therefore requires appropriate quality assurance procedures. In this work, we upgraded the GEANT4-based GATE Monte Carlo platform in order to recalculate the TPS dose distributions in view of further benchmarking. In a first step, we selected an appropriate simulation environment (physics models and parameters) in order to produce accurate and efficient simulations. GATE simulations were validated using measurements and other Monte Carlo codes for depth-dose and transverse profiles. While a good agreement was found for depth-dose profiles, larger discrepancies were pointed out for transverse profiles. In a second step, we developed a modeling method to simulate active scanning beam delivery systems, which does not require to simulate the components of the treatment nozzle. The method has been successfully applied to an IBA proton therapy system and validated against measurements for complex treatment plans. Interfaces have also been developed in order to link DICOM RT ION PLAN and DICOM RT DOSE with GATE. Finally, we compared in a third step the TPS and Monte Carlo dose distributions in homogeneous and heterogeneous configurations. The beam models of both dose engines were in satisfactory agreement, allowing further evaluation of clinical treatment plans. A two-field prostate plan has been evaluated, showing a satisfactory agreement between the TPS and Monte Carlo, and demonstrating the novel capabilities of the platform for the evaluation of the TPS. To summarize, we selected an appropriate simulation environment for proton therapy, proposed a modeling method for active scanning systems and presented a method to compare the TPS and Monte Carlo dose distributions. All tools developed in GATE were or will be publicly released. A detailed validation stage of the system including absolute dosimetry is still necessary, in order to quantitatively evaluate its accuracy in various homogeneous and heterogeneous configurations. In this thesis, we have demonstrated that the GATE Monte Carlo platform is a good candidate for the simulation of active scanning delivery systems, allowing further TPS benchmarking. Moreover, the GATE platform also handles imaging applications, such as PET or prompt-gamma imaging towards online treatment monitoring and paves the way of interdisciplinary research advances.
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Moraes, Paula de Camargo. "Variação entre observadores na aplicação dos critérios morfológicos e cinéticos propostos pelo BI-RADS® (Breast Imaging Reporting and Data System) para ressonância magnética das mamas." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5151/tde-25062008-151029/.
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OBJETIVO. O objetivo deste estudo foi verificar a variação entre observadores, com diferentes graus de treinamento em RM das mamas, na aplicação dos critérios morfológicos e cinéticos propostos pelo BI-RADS® para descrever os realces na RM. Também, buscou-se avaliar a importância desta variação sobre a categorização final e a conduta sugerida, antes e após o conhecimento dos dados clínicos e dos demais exames de imagem pertinentes a cada caso. MÉTODOS. 109 realces, sendo 36 malignos, em 96 mulheres, foram interpretados por quatro radiologistas, divididos em duas duplas de acordo com a experiência em RM das mamas. Cada realce foi descrito seguindo os critérios de interpretação propostos pelo BI-RADS® para RM, sendo posteriormente informada a categoria final e a recomendação sugerida para cada caso. Tanto a categoria final quanto a conduta sugerida foram informadas duas vezes por cada observador, uma vez antes do conhecimento dos dados clínicos e dos demais exames de imagem e outra vez após o conhecimento dos mesmos. A concordância entre os membros de cada uma das duplas quanto à aplicação dos critérios de descrição morfológicos e dinâmicos utilizados na caracterização dos realces foi medida, seguida pela mensuração da concordância quanto à classificação final e a conduta recomendada, tanto antes quanto após o conhecimento dos dados clínicos. O teste kappa foi usado para estimar a concordância entre os observadores além daquela esperada pelo acaso. Visando determinar se as taxas de concordância de uma dupla de observadores eram superiores a da outra dupla, tanto para os critérios de descrição quanto para as categorias finais e condutas sugeridas, o teste de Wilcoxon foi utilizado. RESULTADOS. A concordância entre observadores experientes foi substancial (0,64) para categoria final após o conhecimento dos dados clínicos, moderada para forma dos nódulos (0,44), realce interno dos nódulos (0,41) e recomendação sugerida após o conhecimento dos dados clínicos (0,52). Concordância razoável foi obtida para todos os critérios entre os observadores não experientes, assim como para os demais critérios para os observadores experientes. Os observadores com maior experiência apresentaram maiores taxas de concordância entre si na aplicação dos critérios de descrição morfológicos e dinâmicos propostos pelo BI-RADS®, assim como para categoria final e conduta sugerida. CONCLUSÃO. Experiência prévia em RM das mamas aumenta a concordância entre observadores na aplicação dos critérios propostos pelo BI-RADS® para RM. Conhecimento dos dados clínicos e dos demais exames de imagem também aumenta a concordância para a categoria final e recomendação sugerida, especialmente entre os observadores experientes.OBJECTIVE. The purpose of this study was to assess the variability among observers with different degree of breast MR expertise in the use of the Breast Imaging Reporting and Data System (BI-RADS®) standardized MR lexicon and to evaluate if the variability in lesion description has any implication over lesion final category and management recommendation before and after the knowledge of clinical and other imaging modalities information. MATERIALS AND METHODS. In 96 women, 109 enhancements, including 36 malignant, were interpreted independently by four radiologists divided in pairs according to their experience in breast MR. Each lesion was described using morphologic and dynamic features from the MR BI-RADS® lexicon. A final category and an overall impression were suggested in two occasions, one before and the other after the information about other breast imaging modalities and clinical examination. The agreement between the two members of each pair was measured concerning the description of the enhancement and both final category and recommendation. Kappa statistics were calculated as measures of agreement beyond chance. In order to determine if the rates of agreement in a group were superior then in the other group, the Wilcoxon statistics were used. RESULTS. The experienced interobserver agreement was substantial (0.64) for BI-RADS® final category after the knowledge of clinical information, moderate for mass shape (0.44), mass enhancement (0.41) and management recommendation after clinical knowledge (0.52). Fair agreement was observed for all descriptors among the observer with less experience and for the other descriptors among the experienced ones. The observers with more experience agreed more between themselves for image descriptors and final assessment and recommendation than did the observers with less experience in breast MR. CONCLUSION. Prior experience in breast MRI decreases variability between observers in the application of the criteria proposed by the BI-RADS for MR. Knowledge of relevant information about clinical and other imaging modalities also increased agreement for final category and management recommendation, especially among the experienced radiologists.
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Malkoc, Veysi. "Sequential alignment and position verification system for functional proton radiosurgery." CSUSB ScholarWorks, 2004. https://scholarworks.lib.csusb.edu/etd-project/2535.
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The purpose of this project is to improve the existing version of the Sequential Alignment and Position Verification System (SAPVS) for functional proton radiosurgery and to evaluate its performance after improvement .
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Tuna, Eser Erdem. "PERCEPTION AND CONTROL OF AN MRI-GUIDED ROBOTIC CATHETER IN DEFORMABLE ENVIRONMENTS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1619795928790909.
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Elbita, Abdulhakim M. "Efficient Processing of Corneal Confocal Microscopy Images. Development of a computer system for the pre-processing, feature extraction, classification, enhancement and registration of a sequence of corneal images." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/6463.
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Corneal diseases are one of the major causes of visual impairment and blindness worldwide. Used for diagnoses, a laser confocal microscope provides a sequence of images, at incremental depths, of the various corneal layers and structures. From these, ophthalmologists can extract clinical information on the state of health of a patient’s cornea. However, many factors impede ophthalmologists in forming diagnoses starting with the large number and variable quality of the individual images (blurring, non-uniform illumination within images, variable illumination between images and noise), and there are also difficulties posed for automatic processing caused by eye movements in both lateral and axial directions during the scanning process.
Aiding ophthalmologists working with long sequences of corneal image requires the development of new algorithms which enhance, correctly order and register the corneal images within a sequence. The novel algorithms devised for this purpose and presented in this thesis are divided into four main categories. The first is enhancement to reduce the problems within individual images. The second is automatic image classification to identify which part of the cornea each image belongs to, when they may not be in the correct sequence. The third is automatic reordering of the images to place the images in the right sequence. The fourth is automatic registration of the images with each other. A flexible application called CORNEASYS has been developed and implemented using MATLAB and the C language to provide and run all the algorithms and methods presented in this thesis. CORNEASYS offers users a collection of all the proposed approaches and algorithms in this thesis in one platform package. CORNEASYS also provides a facility to help the research team and Ophthalmologists, who are in discussions to determine future system requirements which meet clinicians’ needs.The data and image files accompanying this thesis are not available online.
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Bai, Yuhui. "Compression temps réel de séquences d'images médicales sur les systèmes embarqués." Thesis, Cergy-Pontoise, 2014. http://www.theses.fr/2014CERG0743.
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Dans le domaine des soins de santé, l'imagerie médicale a rapidement progressé et est aujourd'hui largement utilisés pour le diagnostic médical et le traitement du patient. La santé mobile devient une tendance émergente qui fournit des soins de santé et de diagnostic à distance. de plus, à l'aide des télécommunications, les données médicale incluant l'imagerie médicale et les informations du patient peuvent être facilement et rapidement partagées entre les hôpitaux et les services de soins de santé. En raison de la grande capacité de stockage et de la bande passante de transmission limitée, une technique de compression efficace est nécessaire. En tant que technique de compression d'image certifiée médicale, WAAVES fournit des taux de compression élevé, tout en assurant une qualité d'image exceptionnelle pour le diagnostic médical. Le défi consiste à transmettre à distance l'image médicale de l'appareil mobile au centre de soins de santé via un réseau à faible bande passante. Nos objectifs sont de proposer une solution de compression d'image intégrée à une vitesse de compression de 10 Mo/s, tout en maintenant la qualité de compression. Nous examinons d'abord l'algorithme WAAVES et évaluons sa complexité logicielle, basée sur un profilage précis du logiciel qui indique un complexité de l'algorithme WAAVES très élevée et très difficile à optimiser de contraintes très sévères en terme de surface, de temps d'exécution ou de consommation d'énergie. L'un des principaux défis est que les modules Adaptative Scanning et Hierarchical Enumerative Coding de WAAVES prennent plus de 90% du temps d'exécution. Par conséquent, nous avons exploité plusieurs possibilités d'optimisation de l'algorithme WAAVES pour simplifier sa mise en œuvre matérielle. Nous avons proposé des méthodologies de mise en œuvre possible de WAAVES, en premier lieu une mise en œuvre logiciel sur plateforme DSP. En suite, nous avons réalisé notre implémentation matérielle de WAAVES. Comme les FPGAs sont largement utilisés pour le prototypage ou la mise en œuvre de systèmes sur puce pour les applications de traitement du signal, leur capacités de parallélisme massif et la mémoire sur puce abondante permet une mise en œuvre efficace qui est souvent supérieure aux CPUs et DSPs. Nous avons conçu WAAVES Encoder SoC basé sur un FPGA de Stratix IV de chez Altera, les deux grands blocs coûteux en temps: Adaptative Scanning et Hierarchical Enumerative Coding sont implementés comme des accélérateurs matériels. Nous avons réalisé ces accélérateurs avec deux niveaux d'optimisations différents et les avons intégrés dans notre Encodeur SoC. La mise en œuvre du matérielle fonctionnant à 100MHz fournit des accélérations significatives par rapport aux implémentations logicielles, y compris les implémentations sur ARM Cortex A9, DSP et CPU et peut atteindre une vitesse de codage de 10 Mo/s, ce qui répond bien aux objectifs de notre thèseIn the field of healthcare, developments in medical imaging are progressing very fast. New technologies have been widely used for the support of patient medical diagnosis and treatment. The mobile healthcare becomes an emerging trend, which provides remote healthcare and diagnostics. By using telecommunication networks and information technology, the medical records including medical imaging and patient's information can be easily and rapidly shared between hospitals and healthcare services. Due to the large storage size and limited transmission bandwidth, an efficient compression technique is necessary. As a medical certificate image compression technique, WAAVES provides high compression ratio while ensuring outstanding image quality for medical diagnosis. The challenge is to remotely transmit the medical image through the mobile device to the healthcare center over a low bandwidth network. Our goal is to propose a high-speed embedded image compression solution, which can provide a compression speed of 10MB/s while maintaining the equivalent compression quality as its software version. We first analyzed the WAAVES encoding algorithm and evaluated its software complexity, based on a precise software profiling, we revealed that the complex algorithm in WAAVES makes it difficult to be optimized for certain implementations under very hard constrains, including area, timing and power consumption. One of the key challenges is that the Adaptive Scanning block and Hierarchical Enumerative Coding block in WAAVES take more than 90% of the total execution time. Therefore, we exploited several potentialities of optimizations of the WAAVES algorithm to simplify the hardware implementation. We proposed the methodologies of the possible implementations of WAAVES, which started from the evaluation of software implementation on DSP platforms, following this evaluation we carried out our hardware implementation of WAAVES. Since FPGAs are widely used as prototyping or actual SoC implementation for signal processing applications, their massive parallelism and abundant on-chip memory allow efficient implementation that often rivals CPUs and DSPs. We designed our WAAVES Encoder SoC based on an Altera's Stratix IV FPGA, the two major time consuming blocks: Adaptive Scanning and Hierarchical Enumerative Coding are designed as IP accelerators. We realized the IPs with two different optimization levels and integrated them into our Encoder SoC. The Hardware implementation running at 100MHz provides significant speedup compared to the other software implementation including ARM Cortex A9, DSP and CPU and can achieve a coding speed of 10MB/s that fulfills the goals of our thesis