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Omar, Ahmed M. "Dynamic imaging with gamma camera PET." Thesis, University of Aberdeen, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421358.
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In this thesis we consider the task of dynamic imaging using a gcPET system. Our technique is based on a mathematical method (developed for SPECT), which processes all dynamic projection data simultaneously instead of reconstructing a series of static images individually. The algorithm was modified to account for the extra data that is obtained with gcPET (compared with SPECT). The method was tested using simulated projection data for both a SPECT and a gcPET geometry. These studies showed the ability of the code to reconstruct simulated data with a varying range of half-lives. For SEPCT data the characteristic parameters of half-life (T1/2) and initial activity (A0) were reconstructed with a percentage error of 35.1%, and 40.8% (at 50 iterations) for a 2 minutes half-life, respectively. The reconstruction of gcPET data showed improvement in half-life and activity compared to SPECT data by 27% and 31%, respectively (at 50 iterations). The method was also extended to enable reconstruction of images in which some regions increased in activity while other regions decreased. Information of the spatial location of these images was provided in the form of a mask. The method was applied to experimental data. These data were acquired using a dPET system and re-binned to the gcPET geometry. The results, obtained from dynamic phantoms, showed that the characteristic behaviour could be recovered and that the code produced satisfactory dynamic images. The method was also applied to data from a patient with a tumour. Again, the reconstructed image showed good results compared to the dPET reconstruction. Time activity curves showed a significant difference between the uptake of tumour and myocardium. Finally, we presented a method to deal with the situation where the activity in certain pixels decreases and then increases during the acquisition.
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Holstensson, Maria. "Quantitative gamma camera imaging for radionuclide therapy dosimetry." Thesis, Institute of Cancer Research (University Of London), 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533648.
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Soares, Antonio Jorge Vaz Duarte. "Development of a compact high resolution gamma camera." Thesis, University College London (University of London), 2001. http://discovery.ucl.ac.uk/1349876/.
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The subject of this thesis is the development of new gamma ray imagers for nuclear medicine, in particular for scintimammography. The need for new compact detectors with high spatial resolution led to the design of the wavelength-shifting fibre (WSF) gamma camera, where the position of interaction of gamma rays inside an inorganic scintillator is read out by WSFs. The feasibility of the concept of a WSF gamma camera was assessed by simple analytical calculations and Monte Carlo simulations, based on the known characteristics of the individual components: the wavelength-shifting fibres, the scintillation crystal and the photodetectors. Studies were carried out of the light trapped inside WSFs coupled to CsI(Na) scintillation crystals irradiated by 122 keV gamma rays. The results confirm the feasibility of a WSF gamma camera despite the low light levels trapped in the fibres. Experimental tests of several position sensitive photomultiplier tubes (PSPMT) of the Hamamatsu R5900 series were performed to assess their suitability for the readout of scintillation crystals and of optical fibres in photon counting mode. The latter application is important for the readout of the WSFs signals in a WSF gamma camera. A WSF gamma camera prototype was built and tested. The R5900-M16 PSPMT was used to read out the signals from WSFs. The results confirm earlier predictions about its performance. In particular, the spatial resolution achieved is comparable to that of modern Anger cameras. It is expected that the inherently flexible design of the camera should allow better positioning around the object than conventional Anger cameras, which is important to optimise the spatial resolution of the system. Monte Carlo simulations show that the use of photodetectors with higher quantum efficiency than PSPMTs would significantly improve the intrinsic spatial resolution. A discussion on the most promising candidates for this application is presented.
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Bugby, Sarah Louise. "Development of a hybrid portable medical gamma camera." Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/32939.
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A novel small field of view medical gamma camera - the Compact Gamma Camera (CGC) - has been developed at the University of Leicester to provide portable, high-resolution gamma imaging for applications in nuclear medical imaging. The suitability of this camera for medical imaging is investigated through Monte Carlo simulation, phantom studies and preliminary clinical testing. Quality assurance protocols are adapted for use with small field of view gamma cameras. These protocols are then used to provide a full characterisation of the CGC. The CGC is found to compare favourably to other small field of view systems in development. Phantom studies are described which show that the CGC is well suited to intraoperative imaging, particularly for use in sentinel lymph node biopsy. A Monte Carlo model is described that is designed to simulate the response of a pinholecollimated, scintillator-based gamma camera. The model is shown to accurately model sensitivity and spatial resolution. Previously derived analytical models are shown to be unsuitable for modelling finite source profiles and a new analytical model is described which addresses this shortcoming. This model is used to define appropriate test source sizes for the characterisation of small field of view systems. A modified version of the CGC - the Hybrid Compact Gamma Camera (HCGC) - is described which includes an optical imager in a coaligned configuration. The HCGC allows for functional and anatomical images to be obtained simultaneously. The use of hybrid optical-gamma imaging is novel in small field of view cameras and offers new possibilities for assisting surgeons in localising the site of uptake in procedures such as sentinel node detection.
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Farber, Aaron M. "Coded-Aperture Compton Camera for Gamma-Ray Imaging." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/311555.
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This dissertation describes the development of a novel gamma-ray imaging system concept and presents results from Monte Carlo simulations of the new design. Current designs for large field-of-view gamma cameras suitable for homeland security applications implement either a coded aperture or a Compton scattering geometry to image a gamma-ray source. Both of these systems require large, expensive position-sensitive detectors in order to work effectively. By combining characteristics of both of these systems, a new design can be implemented that does not require such expensive detectors and that can be scaled down to a portable size. This new system has significant promise in homeland security, astronomy, botany and other fields, while future iterations may prove useful in medical imaging, other biological sciences and other areas, such as non-destructive testing. A proof-of-principle study of the new gamma-ray imaging system has been performed by Monte Carlo simulation. Various reconstruction methods have been explored and compared. General-Purpose Graphics-Processor-Unit (GPGPU) computation has also been incorporated. The resulting code is a primary design tool for exploring variables such as detector spacing, material selection and thickness and pixel geometry. The advancement of the system from a simple 1-dimensional simulation to a full 3-dimensional model is described. Methods of image reconstruction are discussed and results of simulations consisting of both a 4 x 4 and a 16 x 16 object space mesh have been presented. A discussion of the limitations and potential areas of further study is also presented.
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Milster, Thomas Dean 1958. "DESIGN AND CONSTRUCTION OF A MODULAR GAMMA CAMERA (NUCLEAR)." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/298720.
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The Anger camera has been used for the last quarter century in many areas of science to image gamma radiation. Some typical applications include medicine, where functionality of organs are studied in vivo, and industrial inspection of fuel rods for nuclear reactors. The standard Anger geometry includes a large scintillation crystal, light guide, photomultiplier array, and analog processing electronics. Even the most modern gamma cameras built today still use the standard Anger design. The work presented here describes an alternative to the standard gamma-camera design that is flexible enough to be used in a wide variety of applications. Especially in single-photon emmission computed tomography (SPECT) applications, the new design has the potential to be more efficient than the standard design. The new design is modular, that is, several small, separate units comprise a system. Each unit consists of a small gamma camera that is optically and electronically independent from other units. The units, called "modular cameras," can be configured around the region of interest so as to provide the maximum amount of information for reconstruction algorithms or direct information to the operator. The theoretical and experimental investigation of this report focuses on the design and construction of the modular cameras. Each modular camera is, in esscence, a small Anger camera. Components of each module include a scintillation crystal, a light guide, and an array of four photomultiplier tubes. Instead of an analog processing network, each module utilizes fast digital circuitry which includes direct analog-to-digital conversion of the photomultiplier signals, a lookup table which maps detector responses to position estimates of the scintillation flashes in the crystal, and an image memory which accumulates the position estimates and forms an image of the radiation incident on the faceplate of the camera. The digital electronics are necessary because analog techniques fail to give satisfactory estimates of scintillation position when the flashes occur near the sides of the crystal. The contents of the lookup table are determined from the statistical properties of the detected signals as a function of scintillation position. Experiments are described in which "best" estimates of position are found by processing data collected from an array of point-source positions in contact with the crystal. Alternative methods for construction of the lookup table are also discussed, which involve computer generation of the estimates. Both maximum-likelihood and mimimum-mean-square-error estimation rules are used, and the results are compared. A mathematical bound on the performance of the estimators is calculated assuming Poisson statistics for the detection process. The bound, which is a Cramer-Rao lower bound, is used to compare module geometries before lookup tables are constructed. A one-dimensional module, which accumulates information along one axis of the faceplate, is designed first. The one-dimensional module provides proof-of-principle evidence for the estimation techniques and is used to determine critical parameters for modular-camera design. The results of the experiments with the one-dimensional camera are extended to two-dimensional designs, which yield position estimates along both axes of the camera faceplate. Several two-dimensional cameras are tested, and an optimum geometry is constructed and tested for spatial resolution and bias of the estimators.
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Ng, Aik Hao. "Hybrid gamma camera imaging : translation from bench to bedside." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49335/.
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There is increasing interest in the use of small field of view (SFOV) portable gamma cameras in medical imaging. A novel hybrid optical-gamma camera (HGC) has been developed through a collaboration between the Universities of Leicester and Nottingham. This system offers high resolution gamma and optical imaging and shows potential for use at the patient bedside, or in the operating theatre. The aim of this thesis was to translate the HGC technology from in vitro laboratory studies to clinical use in human subjects. Pilot studies were undertaken with the HGC as part of this thesis. Furthermore, efforts have been made to transform the HGC technologies into a new medical device, known as Nebuleye. Initial physical evaluation of the pre-production prototype camera was carried out as part of the device developmental process, highlighting some aspects of the design that require further modification. A complete and rigorous testing scheme to assess the pre-production prototype camera has been developed and successfully implemented. The newly introduced tests enabled the system uniformity, system sensitivity, detector head shielding leakage, optical-gamma image alignment and optical image quality of the hybrid camera to be assessed objectively. This harmonised testing scheme allows characterisation and direct comparison of SFOV gamma cameras. In vitro and in vivo preclinical imaging was undertaken to examine the performance of the SFOV gamma cameras for experimental animal studies. The results of animal study have shown for the first time the feasibility and performance of these SFOV gamma cameras for imaging mice injected with a newly developed 111In labelled hybrid tracer. Further investigations are needed to improve the system resolution and prepare the camera system for combined gamma-near infrared fluorescence imaging in future. A systematic in vitro laboratory assessment method has been established to examine the imaging performance of the SFOV gamma camera in radioguided sentinel lymph node biopsy (SLNB) and radioactive seed localisation procedures for breast cancer surgery. Further preparatory work was undertaken to carry out a pilot clinical trial of the use of the pre-production prototype camera in sentinel node localisation procedures during breast cancer surgery. The clinical study protocol and routine quality control procedures have been established and are suitable for future use. Baseline data on the camera performance assessed using the routine quality control scheme have been obtained. Finally, the capabilities of the SFOV gamma camera were assessed. This has provided baseline data on user feedback and the imaging consequences on operator motion effects, as well as examining the detectability of a range of radionuclides, including 99mTc, 111In, 123I, 125I and 75Se. The first clinical results of the use of the HGC in clinical hybrid optical-gamma imaging in patients administered with 99mTc and 123I labelled radiopharmaceuticals have been reported. This clinical study has demonstrated the feasibility and capability of HGC in various clinical applications performed at the patient bedside, which included patients undergoing bone, thyroid, lacrimal drainage and lymphatic imaging as well as DaTscan studies. In conclusion, the work in this thesis has demonstrated the successful translation of an SFOV hybrid gamma camera for clinical use. This system would be ideally suited for use in the operating theatre for radioguided procedures such as sentinel node detection and tumour localisation. This system also offers potential for use with the new generation of hybrid fluorescent-radionuclide tracers currently under development.
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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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Roellinghoff, Frauke. "Design and implementation of a prompt-gamma camera for real-time monitoring of ion beam therapy." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0024.
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La protonthérapie est une technique prometteuse pour le traitement du cancer, qui se répend de plus en plus. Le pic prononcé de son profil de dose ainsi que la longueur finie du parcours des particules rendent possible un traitement plus ciblé et permettent de mieux éviter d’endommager des tissus sains. Cependant, la précision de l’irradiation s’avère également être le risque principal lors de l’utilisation de cette technique. En effet, une erreur dans la profondeur de pénétration des particules pourrait engendrer des dégâts considérables. A l’heure actuelle, aucune méthode de contrôle n’est systématiquement utilisée pour s’assurer de la qualité du traitement. Dans ce manuscrit, une méthode indirecte de mesure de la distribution de dose, basé sur la détection de gammas prompts émis le long du parcours du faisceau, est étudiée. Deux concepts de caméra collimatée uni-dimensionnelle sont comparés à l’aune de leur utilisation potentielle : une caméra à fentes parallèles et une caméra “knife-edge”. Les deux systèmes sont optimisés par simulations de Monte Carlo et des mesures sont présentés pour valider ces simulations. La comparaison se base sur la précision avec laquelle un décalage dans la chute du profil prompt gamma peut être détecté, la résolution spatiale, le coût et la taille du système. Des recommandations sont émises pour le choix de la meilleure configuration, selon différentes exigeances. Des résultats similaires sont obtenus pour les deux concepts, atteignant une précision de environ 2 mm pour un seul point de “pencil beam” correspondant à 5e7 protons. L’étude se conclue par un tour d’horizon des pistes de recherche futures qui permettraient d’utiliser un système de détection de gammas prompts dans un contexte clinique futurProtontherapy is a promising technique for tumor treatment that is becoming more and more widespread. The sharply peaked profile of the dose and the finite particle range allow for very conformal treatment and better sparing of healthy tissue beyond the tumor, but he precise delivery also proves to be the biggest challenge of the technique. Errors in range are a considerable risk in proton therapy and no range monitoring method is currently systematically used for quality control. In this manuscript, an indirect method of measuring the dose distribution, via the detection of secondary prompt gamma radiation emitted along the beam path, is explored. Two different one-dimensional collimated camera concepts, a multi-parallel-slit camera and a knife-edge slit camera are compared with regards to their potential use. Both systems are optimized via Monte Carlo simulation and measurements are presented for validation. The comparison is made on the basis of the precision with which a shift in the prompt gamma profile falloff edge can be retrieved by comparison with a reference profile as well as the spatial resolution, the cost, weight and bulkiness of the system and guidelines are given for choosing the best configuration for different requirements. Similar values can be obtained for both concepts, reaching a precision for the retrieval of the falloff edge of around 2 mm for a single pencil beam spot of 5×107 protons. This study concludes with an outlook on future developments and areas of investigation with the goal of reaching clinical applicability of a prompt gamma detection system
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Fontana, Mattia. "Tests and characterization of gamma cameras for medical applications." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1285/document.
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Ce travail de thèse a été effectué dans le cadre de la collaboration CLaRyS, qui a pour objectif le développement d'une caméra gamma multi-collimatée et d'une caméra Compton pour les applications médicales notamment pour le contrôle en ligne de l’hadronthérapie. La caméra Compton pourrait également être utilisée en médecine nucléaire. L’objectif principal de ce travail de thèse était la caractérisation complète des détecteurs qui composent les caméras et le test des deux systèmes complets avec des faisceaux d’ions cliniques. En parallèle, des études en simulation ont permis d'estimer les performances de la caméra Compton à la fois pour le contrôle de l’hadronthérapie et la médecine nucléaireThis thesis work has been carried out within the CLaRyS French collaboration, which is involved in the development of a multi-collimated gamma camera and a Compton camera for the application in ion beam therapy monitoring through prompt-gamma detection and in nuclear medicine examinations. The main goal of the thesis was the complete characterization of the camera detector components, and the test of the whole systems on clinical ion beams. In parallel, simulation works have been performed to assess the performance of the Compton camera for the measurement of ion range during proton and carbon therapy, and for single photon emission computed tomography application in the nuclear medicine field
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Wang, Beien. "3D Scintillation Positioning Method in a Breast-specific Gamma Camera." Thesis, KTH, Medicinsk teknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176453.
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In modern clinical practice, gamma camera is one of the most important imaging modalities for tumour diagnosis. The standard technique uses scintillator-based gamma cameras equipped with parallel-hole collimator to detect the planar position of γ photon interaction (scintillation). However, the positioning is of insufficient resolution and linearity for breast imaging. With the aim to improve spatial resolution and positioning linearity, a new gamma camera configuration was described specifically for breast-imaging. This breast-specific gamma camera was supposed to have the following technical features: variable angle slant-hole collimator; double SiPM arrays readout at the front and back sides of the scintillator; diffusive reflectors at the edges around the scintillator. Because slant-hole collimator was used, a new 3D scintillation positioning method was introduced and tested. The setup of the gamma detector was created in a Monte Carlo simulation toolkit, and a library of a number of light distributions from known positions was acquired through optical simulation. Two library-based positioning algorithms, similarity comparison and maximum likelihood, were developed to estimate the 3D scintillation position by comparing the responses from simulated gamma interactions and the responses from library. Results indicated that the planar spatial resolution and positioning linearity estimated with this gamma detector setup and positioning algorithm was higher than the conventional gamma detectors. The depth-of-interaction estimation was also of high linearity and resolution. With the results presented, the gamma detector setup and positioning method is promising in future breast cancer diagnosis.
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De, Franco Andrea. "Development of a camera for Tera-electron Volt gamma-ray astronomy." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:bfa00ea0-3be1-455c-9f82-3429e4bef0da.
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In this thesis I describe the development of a compact camera for ground-based multi TeV gamma-ray astronomy, using the Imaging Atmospheric Cherenkov Telescope (IACT) technique. The camera is based on multi-anode photomultipliers (MAPM) and is designed for use on the Gamma Cherenkov Telescope (GCT), which is proposed to be part of the Small Size Telescope (SST) array of the Cherenkov Telescope Array (CTA). GCT achieves high performance with a compact and cost efficient design via a Schwarzschild-Couder (SC) dual-mirror optical system. The GCT optical design allows the use of a compact camera of diameter roughly 0.5 m. The curved focal plane is equipped with 32 tiles of 64-pixels MAPM for a total of 2048 pixels of ~0.2° angular size, resulting in a field of view of ~9°. The GCT camera is designed to record the flashes of Cherenkov light from electromagnetic cascades, which last only a few tens of nanoseconds. I give a detailed description of the design, the challenges encountered during testing in the lab, and the performance of the most critical components. I give details on the custom front-end electronics modules that provide the required fast electronics, facilitating sampling and digitization, as well as first level of triggering. The camera-level triggering system is a custom backplane, developed to reject spurious triggers on the night sky background, which typically is of the order of few tens of millions of photons per pixel per second. This is to be compared with the rate of the astrophysical signal, which is of the order of few hundreds of events per second at the relevant energies. Additionally I provide a detailed description of all the software needed for the data acquisition and control of the camera, from the very low level drivers to high level and user friendly processes. I follow the commissioning of the camera, from the individual core components to the integration of the system. I then describe the integration of the camera on the GCT prototype telescope structure, and the achievement of "first light", validating for the first time the full proof-of-concept of an IACT with SC optics. I also report a study I performed on expectations for an extragalactic survey for blazars with CTA. The cumulative source count distribution of blazars is presented, including implications from two different phenomena: axion-like particle (ALP) to gamma-ray oscillations in the intergalactic magnetic field, and secondary gamma rays from hadronic origins. I conclude that a shallow and wide survey will provide the best science return for CTA, that the impact of ALP is modest and that the secondary mechanism of gamma-ray production would allow detection of blazars up to redshift of 1 in the multi-TeV energy band.
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Persson, Mikael. "Development of a Mobile Tomographic Gamma Camera Based on Ectomography - Cardiotom." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3238.
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Lodge, Martin Anthony. "A rotating slat collimator for planar and tomographic gamma-camera imaging." Thesis, Institute of Cancer Research (University Of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362842.
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Blundell, Helen Louise. "The influence of accurate attenuation correction on quantitative gamma camera imaging." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/46469/.
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Gamma camera systems are used in a variety of diagnostic applications to image and in some cases measure, the physiological uptake of a radioactive tracer within the body. A number of factors, particularly attenuation and scatter of photons within the body tissues can cause degradation of image quality and inaccuracies in the measurement of tracer uptake. Single photon emission tomography (SPECT) systems which incorporate an xray computed tomography (CT) facility have enabled accurate transmission images of the patient to be obtained. These ‘attenuation maps’ can be used to correct the SPECT images for the effects of attenuation. The aim of this project was to investigate the use of an x-ray CT based attenuation correction (AC) system in SPECT gamma camera imaging. The use of AC with other physical parameters of the imaging process including scatter was firstly examined in order to determine the optimum imaging parameters required to maximise image quality. The influence of attenuation, scatter and other imaging parameters on the accuracy of absolute and relative quantitative measurements was then investigated. The methodology involved using the GE Millenium Hawkeye gamma camera system to obtain images of a range of phantoms filled with various concentrations of radioactivity; from simple point sources to phantoms which simulate organs of the body. An attempt was made to establish SPECT sensitivity values that would allow accurate determination of activity in a region of interest. These sensitivity values were applied to all subsequent measurements and a measure made of quantitative accuracy. The results showed that the sensitivity value used for quantitative SPECT measurements must reflect the reconstruction method and corrections used in the acquisition. Attenuation correction proved to be more significant than scatter correction in quantitative accuracy, with activity results being within 30% of expected values in all cases where AC was used.
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Natarajamani, Deepa. "A Novel Technique to Improve the Resolution of a Gamma Camera." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1342814846.
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Paradiso, Vincenzo. "Development of a portable gamma camera for accurate 3-D localization of radioactive hotspots." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC209.
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Le présent travail a pour but le développement d’une caméra gamma à masque codé permettant d’estimer la position tridimensionnelle (3D) des sources radioactives. Cela est d’un intérêt considérable dans le cadre d’un grand nombre d'applications, de la reconstruction de la forme 3D des objets radioactifs aux systèmes de réalité augmentée appliqués à la radioprotection. Les caméras gamma portables actuelles ne fournissent que la position angulaire relative des sources gamma à localiser, c'est-à-dire qu'aucune information métrique concernant les sources n’est disponible, comme par exemple leur distance par rapport à la caméra. Dans cette thèse, nous proposons principalement deux approches permettant d’estimer la position 3D des sources. La première approche consiste à étalonner la caméra gamma avec un capteur de profondeur à lumière structurée. La seconde approche permet d'estimer la distance source-détecteur par une méthode d’imagerie gamma stéréoscopique. Pour aligner géométriquement les images obtenues par la caméra gamma, le capteur de profondeur, et la caméra optique, une procédure d'étalonnage n’utilisant qu’une seule source ponctuelle radioactive a été conçue et mise en œuvre. Les résultats expérimentaux démontrent que les approches proposées permettent d'obtenir une précision inférieure au pixel, tant pour l’erreur de reprojection que pour la superposition des images gamma et optiques. Ces travaux présentent également une analyse quantitative de la précision et de la résolution relatives à l’estimation de la distance source-détecteur. De plus, les résultats obtenus ont validé le choix de la géométrie du modèle sténopé pour les caméras gamma à masque codéA coded aperture gamma camera for retrieving the three-dimensional (3-D) position of radioactive sources is presented. This is of considerable interest for a wide number of applications, ranging from the reconstruction of the 3-D shape of radioactive objects to augmented reality systems. Current portable γ-cameras only provide the relative angular position of the hotspots within their field of view. That is, they do not provide any metric information concerning the located sources. In this study, we propose two approaches to estimate the distance of the surrounding hotspots, and to autonomously determine if they are occluded by an object. The first consists in combining and accurately calibrating the gamma camera with a structured-light depth sensor. The second approach allows the estimation of the source-detector distance by means of stereo gamma imaging. To geometrically align the images obtained by the gamma, depth, and optical cameras used, a versatile calibration procedure has been designed and carried out. Such procedure uses a calibration phantom intentionally easy to build and inexpensive, allowing the procedure to be performed with only one radioactive point source. Experimental results showed that our calibration procedure yields to sub-pixel accuracy both in the re-projection error and the overlay of radiation and optical images. A quantitative analysis concerning the accuracy and resolution of the retrieved source-detector distance is also provided, along with an insight into the respective most influential factors. Moreover, the results obtained validated the choice of the geometry of the pinhole model for a coded aperture gamma camera
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Woldeselassie, Tilahun. "A simple microcomputer-based nuclear medicine data processing system design and performance testing." Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316066.
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This thesis investigates the feasibility of designing a simple nuclear medicine data processing system based on an inexpensive microcomputer system, which is affordable to small hospitals and to developing countries where resources are limited. Since the main need for a computer is to allow dynamic studies to be carried out, the relevant criteria for choosing the computer are its speed and memory capacity. The benchmark chosen for these criteria is renography, one of the commonest nuclear medicine procedures. The Acorn Archimedes model 310 microcomputer was found to meet these requirements, and a suitable camera-computer interface has been designed. Because of the need for ensuring that the gain and offset controls of the interface are set optimally before connecting to the camera, it was necessary to design a circuit which produces a test pattern on the screen for use during this operation. Having also developed and tested the data acquisition and image display software successfully, atttention was concentrated on finding ways of characterising and measuring the performance of the computer interface and the display device, two important areas which have been largely neglected in the quality control of camera-computer systems. One of the characteristics of the interface is its deadtime. A procedure has been outlined for measuring this by means of a variable frequency pulse generator and also for interpreting the data correctly. A theoretical analysis of the way in which the interface deadtime affects the overall count rate performance of the system has also been provided. The spatial linearity, resolution and uniformity characteristics of the interface are measured using a special dual staircase generator circuit designed to simulate the camera position and energy signals. The test pattern set up on the screen consists of an orthogonal grid of points which can be used for a visual assessment of linearity, while analysis of the data in memory enables performance indices for resolution, linearity and uniformity to be computed. The thesis investigates the performance characteristics of display devices by means of radiometric measurements of screen luminance. These reveal that the relationship between screen luminance and display grey level value can be taken as quadratic. Characterisation of the display device in this way enables software techniques to be employed to ensure that screen luminance is a linear function of display grey level value; screen luminance measurements, coupled with film density measurements, are also used to optimise the settings of the display controls for using the film in the linear range of its optical densities. This in turn ensures that film density is a linear function of grey level value. An alternative approach for correcting for display nonlinearity is by means of an electronic circuit described in this thesis. Intensity coding schemes for improving the quality of grey scale images can be effective only if distortion due to the display device is corrected for. The thesis also draws attention to significant variations in film density which may have their origins in nonuniformities in the display screen, the recording film, or in the performance of the film processor. The work on display devices has been published in two papers.
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Ballami, Nasser Salim. "Qualitative and quantitative aspect of multigated myocardial perfusion." Thesis, University of Surrey, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336521.
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Fernandez, Gangoso Diane. "Etude des vestiges de supernova en intéraction avec l'expérience d'astronomie H.E.S.S. et étalonnage de la caméra H.E.S.S. II." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20154/document.
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La découverte du rayonnement cosmique remonte à plus d'un siècle, mais son origine est encore incertaine aujourd'hui. Divers éléments théoriques et observationnels tendent à confirmer que les vestiges de supernova (SNRs) sont à l'origine de la majeure partie du rayonnement cosmique galactique jusqu'à des énergies de ~3 PeV, voire au-delà. Mais ce paradigme requiert encore une preuve irréfutable.Lors de l'expansion d'un SNR, les particules chargées du milieu circumstellaire/interstellaire sont accélérées par l'onde de choc et peuvent alors rayonner depuis le domaine radio jusqu'aux très hautes énergies (>100 GeV). Les mécanismes d'accélération et les processus d'émission des particules ont été étudiés et modélisés au cours de cette thèse.Les instruments d'astronomie Gamma permettent de détecter les rayonnements émis par les particules accélérées au choc des SNRs. En particulier, le télescope à création de paires Fermi-LAT et le réseau de télescopes au sol à imagerie Tcherenkov atmosphérique H.E.S.S. détectent, à eux deux, des photons Gamma d'énergie comprise entre ~30 MeV et plusieurs dizaines de TeV. Au cours de cette thèse, réalisée dans le cadre de l'expérience H.E.S.S., les données observationnelles de plusieurs SNRs ont été analysées et interprétées. Les études menées ont conduit à la détection d'une des sources les plus faibles encore jamais détectée et dont l'émission Gamma est associée à l'interaction du SNR G349.7+0.2 avec un nuage moléculaire adjacent. Des limites supérieures sur les flux intégrés de nombreux SNRs ont été extraites afin de contraindre les modèles d'accélération de particules. Le SNR Puppis A présente notamment un comportement spectral inattendu, difficile à expliquer dans le cadre des modèles d'accélération de particules actuels.Un cinquième télescope, de plus grande taille, a été ajouté mi-2012 au réseau de quatre petits télescopes H.E.S.S. afin d'abaisser le seuil en énergie et d'améliorer la sensibilité du réseau. Dans ce cadre, j'ai activement participé au développement, à l'intégration et à l'analyse des données du dispositif d'étalonnage de la caméra de ce cinquième télescopeThe discovery of Cosmic Rays (CRs) dates back more than one century ago, however their origin remains unclear. There is rather convincing evidence that the bulk of Galactic CRs, up to ~3 PeV, and possibly beyond, is accelerated in supernova remnants (SNRs). However this paradigm still needs a conclusive proof. While the SNR expands, charged particles from the circumstellar/interstellar medium are accelerated at the SNR shock wave and radiate from radio to very high energies (>100 GeV). Particles acceleration and broad band radiation mechanism were studied and modelled during this PhD. $gamma$-ray astronomy instruments enable to detect radiation from particles accelerated at the SNR shock wave. In particular the pair creation telescope Fermi-LAT and the array of imaging atmospheric Cherenkov telescopes H.E.S.S., enable together to detect Gamma-ray photons in the ~30 MeV-30 TeV energy range. As a member of the H.E.S.S. collaboration, I analysed and interpreted observational data from several Galactic SNRs. These studies led to the discovery of one of the faintest sources ever detected whose Gamma-ray emission is associated with the interaction of the SNR G349.7+02 with an adjacent molecular cloud. Upper limits on the integrated flux of many SNRs were extracted in order to constrain models of particle acceleration. In particular, the SNR Puppis A shows an unexpected spectral behavior difficult to explain with current models. A fifth bigger telescope was added mid 2012 to the H.E.S.S. array of four small telescopes to lower the energy threshold and to improve the sensitivity of the array. In this context I actively participated to the development, integration end data analysis of the calibration hardware of the camera of this fifth telescope
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Cinti, Maria Nerina. "Study and realization of a high resolution gamma camera prototype for Scintimammography in Nuclear Medicine, inside I.M.I. project." Doctoral thesis, La Sapienza, 2005. http://hdl.handle.net/11573/916831.
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Alnafea, Mohammed. "Coded aperture breast tumour imaging using a full-size clinical gamma camera." Thesis, University of Surrey, 2007. http://epubs.surrey.ac.uk/804432/.
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Alqahtani, Mohammed Saeed Mohammed. "Assessment of a novel small field of view medical hybrid gamma camera." Thesis, University of Leicester, 2018. http://hdl.handle.net/2381/43070.
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Small field of view (SFOV) gamma detection and imaging technologies for monitoring in vivo tracer uptake are rapidly expanding and being introduced for bed-side imaging and image guided surgical procedures. The Hybrid Gamma Camera (HGC) has been developed, at the University of Leicester, to enhance the localisation of targeted radiopharmaceuticals during surgical procedures, for example in sentinel lymph node (SLN) biopsies, and for bed-side imaging in small organ gamma imaging procedures such as lacrimal scintigraphy and thyroid scintigraphy. In this thesis, prototype medical phantoms including anthropomorphic three-dimensional printed phantoms have been designed, constructed, and evaluated using representative modelled medical scenarios to study the capability of the HGC to detect SLNs and image small organs. Furthermore, the results of the first clinical feasibility study of the HGC has been discussed. The HGC was used to perform non-invasive hybrid gamma-optical imaging procedures on patients attending their routine scint32igraphic imaging appointments in a nuclear medicine clinic. Various quantitative and qualitative assessments have been conducted on different phantom configurations including simulating targeted tissues at several depths and using different radioactivity concentrations. Two generations of the HGC have been utilised, having two different thicknesses of columnar CsI(Tl) scintillator, and two pinhole collimator diameters (0.5 mm and 1.0 mm). Additionally, the behaviour of the HGC at a range of imaging distances and acquisition times has been examined. All of these factors were considered to judge the detection limitations of the HGC. The results demonstrate that the HGC was ideally suited for small organ imaging. The HGC capability to detect low activity uptake in small SLNs indicates its usefulness as an intraoperative imaging system during surgical SLN procedures. The ability of the HGC to utilise both pinhole collimators enhances its practicality and improves its ability to meet the needs of SFOV gamma imaging.
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Jawa, Zabah Muhammad. "Optimal utilization of gamma camera time in Tc-99m MDP bone scintigraphy." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/1824.
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Thesis (MScMedSc (Medical Imaging and Clinical Oncology. Nuclear Medicine))--University of Stellenbosch, 2007.Introduction: Whole body bone scintigraphy with Tc-99m MDP is able to provide a survey of the entire skeleton. The question arises if it is mandatory to perform a whole body bone scan in all patients, irrespective of the clinical indication. The aim of this study is to determine the implications of performing limited imaging in patients who had whole body bone scan for various clinical patholgy with Tc-99m MDP, in order to determine if limited imaging would be acceptable in selected pathologies. This may enable gamma camera time to be optimally utilized in units with limited facilities. Materials and Methods: Reports of 3015 patients with various clinical pathologies who had whole body bone scans with Tc-99m MDP in our department from January 2002 to December 2004 were retrospectively reviewed. The presence of pathologic radiotracer uptake was analyzed in order to establish the pattern of distribution. Clinically significant skeletal lesions were classified according to the anatomical regions where they were located viz; skull (including the neck), axial skeleton (including the pelvis and shoulders) and limbs. Results: Our results showed that in patients with lung cancer, soft tissue sarcoma, and myeloma, there was an error in more than 25% of patients when limited imaging was performed. In patients with cancer of the breast, prostate, kidney, gastrointestinal system, and reproductive system and lymphoma there is an error in less than 5% of patients when limited imaging is employed. For iv patients with more localized musculoskeletal disorders such as suspected stress fractures, complicated joint prosthesis and avascular necrosis of the femur head, regional imaging of the area of pathology showed a percentage error of less than 6%.
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SOLOP, ANASTASIIA. "VALUTAZIONE RISERVA PERFUSORIA MIOCARDICA MEDIANTE GAMMA CAMERA A SEMICONDUTTORI: VANTAGGI E LIMITI." Doctoral thesis, Università degli Studi di Milano, 2023. https://hdl.handle.net/2434/950957.
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L’obiettivo dello studio. Imaging di perfusione miocardica (MPI) con la tomografia computerizzata a emissione di singolo fotone (SPECT) è un importante strumento diagnostico non invasivo nella diagnosi, stratificazione del rischio e prognosi per la malattia delle arterie coronarie (CAD). La valutazione quantitativa del flusso sanguigno miocardico (MBF) e della riserva di flusso coronarico (CFR) consente un giudizio sulla gravità della CAD, il monitoraggio della sua progressione e la valutazione dell'efficacia di strategie terapeutiche anti-ischemiche. La PET/TC è considerata lo standard per le valutazioni quantitative del MBF, ma richiede traccianti di breve emivita, costosi e non ampiamente disponibili. La SPECT con i rivelatori del Tellururo di Cadmio e Zinco (CZT) permette l'acquisizione dinamica e la quantificazione del MBF. Lo scopo del presente studio è di valutare degli indici del MBF e della CFR con 99mTc-tetrofosmina su una CZT SPECT del reparto di Medicina Nucleare presso l’Istituto Maugeri IRCCS Veruno e confrontarli con quelli ottenuti con 13N-NH3 su una PET/CT presso reparto di Medicina Nucleare ASST- Spedali Civili di Brescia. Inoltre, abbiamo esaminato i valori del MBF e della CFR con due diverse posizioni della ROI 3D utilizzata per l'estrazione della funzione di ingresso (nella cavità del VS – metodo 1 (M1) ed in sede valvolare – metodo 2 (M2) per capire, se questo fattore risulta vincolante per l’analisi. Materiali e metodi. Sono stati valutati 8 pazienti a riposo e sotto lo stress farmacologico con 99mTc-tetrofosmina-CZT. Il MBF e la CFR sono stati misurati da CZT senza AC (NAC-CZT) con due diverse posizioni della ROI 3D per la funzione di ingresso (input function): nella cavità del ventricolo sinistro (M1) ed in sede valvolare (M2). Successivamente è stato effettuato il confronto con i dati ottenuti con 13N-NH3 su una PET/CT presso il reparto di Medicina Nucleare ASST- Spedali Civili di Brescia. Risultati. Nelle misurazioni del MBF a riposo e sotto stress e della CFR globali tra la NAC-CZT (M1 e M2) e la PET è stata rilevata una correlazione statisticamente significativa tra i valori del MBF sotto stress ottenuti con la NAC-CZT M2 e la PET (P = 0,0164). I valori della CFR globali e regionali valutati sia con NAC-CZT M1 che NAC-CZT M2 non sono statisticamente correlabili con quelli ottenuti con la PET (P per tutti i confronti > 0,05). Tuttavia, i valori della CFR ottenuti con NAC-CZT M1 vs NAC-CZT M2 si correlano bene sia a livello globale (P = 0,0247) che a livello regionale nei territori LAD (P = 0,0227) e LCX (P = 0,0246), mentre è assente la correlazione significativa nel territorio RCA (P = 0, 2045). Conclusioni. La misurazione del MBF e della CFR ad oggi è diventata possibile nella pratica clinica grazie alla diffusa disponibilità della CZT-SPECT, il software integrato risulta riproducibile e non è vincolato dal lavoro dell’operatore. La correlazione tra la CZT e la PET/TC non è perfetta e quindi la CZT ancora non può essere considerata completamente sostitutiva per la misurazione del MBF e della CFR. Multiple sfide tecniche e incongruenze contribuiscono all’imprecisione complessiva della misurazione della CFR con la SPECT, con conseguente variazione delle sue stime e delle diverse soglie per il rilevamento dell'ischemia tra i vari studi sui pazienti e i diversi centri di imaging. Pertanto, dato il rischio di una sovra o sotto-diagnosi in base alla bassa accuratezza delle misure, l’utilizzo di questo metodo nella pratica clinica va impiegato solo selettivamente e con cautela. Infine, per una valutazione appropriata del paziente, i valori della CFR dovrebbero essere interpretati in combinazione con gli altri indicatori validati di malattia, compresi i modelli di perfusione e le misure funzionali, così come la storia clinica
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Bricou, Alexandre. "APPLICATION D'UN RADIO-IMAGEUR (TRECAM) DANS LES CANCERS INVASIFS INFRA-CLINIQUES DU SEIN." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS561/document.
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Depuis son émergence, la médecine nucléaire ne cesse d’évoluer. A la fois diagnostique et thérapeutique, elle occupe une place importante dans la stratégie médicale moderne. L’imagerie nucléaire consiste après injection au patient d’un radiotraceur, à détecter le rayonnement émis. Elle donne accès quantitativement à la fonctionnalité des organes ou à la localisation de structures cibles telles que des lésions tumorales. Cette imagerie a naturellement intégré les procédures chirurgicales en particulier en cancérologie (en pré et per opératoire). On parle de chirurgie radioguidée. Cette dernière permet de localiser lors du geste chirurgical les structures radiomarquées devant être retirées.Les avancées technologiques au niveau des radiopharmaceutiques et en instrumentation sont à l’origine de nouvelles stratégies de radioguidages pouvant cibler de petites structures. L’imagerie par rayonnement gamma reste la plus répandue et la mieux adaptée. On assiste au développement de dispositifs d’imagerie gamma portables miniaturisés permettant un contrôle visuel en per opératoire. Ces dispositifs sont prometteurs mais doivent être évalués.Un état des lieux des différentes procédures en chirurgie radioguidée et des imageurs utilisés en clinique est réalisé dans cette thèse.Le laboratoire Imagerie et Modélisation en Neurobiologie et Cancérologie (UMR 8165) développe de longue date de nouvelles approches de détection miniaturisée pour les différents types de rayonnement. Parmi celles-ci le prototype de deuxième génération appelé TReCam.Cette mini gamma caméra présente un champ de vue de 4,9 x 4,9 cm2 et intègre des technologies d’imagerie directement issues de la physique des particules. Elle est formée d’un collimateur à trous parallèles, d’un scintillateur continu LaBr3 (Ce) lu par un photomultiplicateur multi-anode et son électronique. Le système d’acquisition donne au chirurgien un affichage en temps réel de l’image radioactive.Ce travail de thèse a consisté également à évaluer la place des imageurs portables en chirurgie radioguidée, en particulier mammaire, à travers l’évaluation de la procédure SNOLL (repérage par marquage ɣ de la tumeur (T) et des ganglions sentinelles (GS)) avec TreCam. Il a reposé sur trois parties.Un premier volet a visé l’optimisation des performances de TReCam pour favoriser la localisation de structures peu radioactives dans des temps d’exposition de l’ordre de la dizaine de secondes. Pour ce faire, différentes stratégies d’optimisation des performances ont été mises en place au niveau du collimateur, de l’électronique et des algorithmes de traitement (dont réseaux de neurones) pour améliorer l’homogénéité de la détection.Le deuxième volet visait à objectiver les performances cliniques de TReCam pour la procédure SNOLL et situer les limites de son exploitation. A l’aide de simulations menées sur la plateforme GATE et modélisant la scène opératoire au plus près de la réalité clinique, nous avons montré que TreCam peut détecter des GS jusqu’à 4,5 cm de profondeur et situé à 4 cm de la T. L’impact du temps de pose n’est pas important. Par contre, le choix de la bonne fenêtre en énergie est primordial.Enfin, le troisième volet concrétise l’ambition interdisciplinaire de cette thèse. Il est consacré à l’évaluation clinique de TReCam à travers l’étude de son apport à la procédure SNOLL mammaire. Cette étude prospective interventionnelle incluant de 47 patientes (22 procédures SNOLL utilisant TReCam aux différents temps de la procédure et 25 procédures SNOLL standard). Les résultats ont montré un intérêt qualitatif à l’utilisation de TReCam en apportant un confort visuel lors de la procédure en complément de la sonde monopixel.Ce travail a montré l’intérêt de tels imageurs en chirurgie radioguidée mais aussi situé leurs limites actuelles. Des efforts de développement doivent être poursuivis tant au niveau des détecteurs qu’au niveau des radiopharmaceutiques utilisés pour le repérageSince its emergence in the middle of the twentieth century, nuclear medicine continues to evolve. At the same time diagnostic and therapeutic, it occupies an increasingly important place in the modern medical strategy. Nuclear imaging consists of injecting the patient with a radio-tracer to detect the radiation emitted. It provides quantitative access to the functionality of organs or the location of target structures such as tumor lesions. This imaging has been naturally integrated into surgical procedures, particularly in oncology (preoperatively and then intraoperatively). It is called radio-guided surgery. It makes possible to locate the radioactive target which will be removed during surgery.Technological advances in radiopharmaceutical instrumentation are driving new strategies that can target small structures. Gamma-ray imaging remains the most widespread and the most suitable. We are witnessing the development of miniaturized portable gamma imaging devices that allow visual control during surgery. These devices are promising but need to be evaluated.A short state-of-the-art of the various procedures in radioguided surgery and imagers used clinically is carried out in this thesis.For many years, the Imaging and Modeling in Neurobiology and Oncology Laboratory (UMR 8165) has been developing new miniaturized detection approaches for different types of radiation. Among them is the second-generation prototype called TReCam.This mini gamma camera has a field of view of 4.9 x 4.9 cm2 and integrates imaging technologies directly from particle physics. It consists of a collimator with parallel holes, a continuous scintillator LaBr3 (Ce) read by a multi-anode photomultiplier (PSPMT) and its electronics. The acquisition system gives the surgeon a real-time display of the radioactive image.This thesis work also consisted in evaluating the place of portable imagers in radioguided surgery, in particular mammary surgery, through the evaluation of the SNOLL procedure (identification of the tumor (T) and the sentinel lymph nodes (GS) by γ-labeling) with TreCam. It is based on three parts.The first part aimed at optimizing the performance of TReCam to improve the localization of lowradioactive structures with exposure times of around 10 seconds. To do this, different performance optimization strategies have been implemented in the collimator, electronics and processing algorithms (including neural networks) to improve the homogeneity of the detection. These performances were compared to those of a prototype developed at IMNC and integrating a new generation of photodetectors: the SiPM.The second part aimed to objectify the clinical performance of TReCam in the SNOLL procedure and to situate the limits of its exploitation. Using simulations conducted on the GATE platform and modeling the operating scene closer to clinical reality, we have shown that TreCam can detect GS up to 4.5 cm deep and located 4 cm from the T. Impact of the exposure time is not important. On the other hand, choosing the right energy window is essential.Finally, the third part concretizes the interdisciplinary ambition of this thesis. It is devoted to clinical evaluation of TReCam through the study of its contribution to the SNOLL breast procedure. This prospective interventional study included 47 patients (22 SNOLL procedures using TReCam at different times of the procedure and 25 standard SNOLL procedures). The results showed a qualitative interest in the use of TReCam by bringing a visual comfort during the procedure and must be used in addition to the monopixel probes.This work has shown the interest of such imagers in radioguided surgery but also set their current limits. Development efforts must be pursued at the level of both detectors and radiopharmaceuticals used for tracking
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Frandes, Mirela. "Gamma-ray detection and Compton camera image reconstruction with application to hadron therapy." Lyon, INSA, 2010. http://theses.insa-lyon.fr/publication/2010ISAL0067/these.pdf.
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A novel technique for radiotherapy - hadron therapy - irradiates tumors using a beam of protons or carbon ions. Hadron therapy is an effective technique for cancer treatment, since it enables accurate dose deposition due to the existence of a Bragg peak at the end of particles range. Precise knowledge of the fall-off position of the dose with millimeters accuracy is critical since hadron therapy proved its efficiency in case of tumors which are deep-seated, close to vital organs, or radio-resistant. A major challenge for hadron therapy is the quality assurance of dose delivery during irradiation. Current systems applying positron emission tomography (PET) technologies exploit gamma rays from the annihilation of positrons emitted during the beta decay of radioactive isotopes. However, the generated PET images allow only post-therapy information about the deposed dose. In addition, they are not in direct coincidence with the Bragg peak. A solution is to image the complete spectrum of the emitted gamma rays, including nuclear gamma rays emitted by inelastic interactions of hadrons to generated nuclei. This emission is isotropic, and has a spectrum ranging from 100 keV up to 20 MeV. However, the measurement of these energetic gamma rays from nuclear reactions exceeds the capability of all existing medical imaging systems. An advanced Compton scattering detection method with electron tracking capability is proposed, and modeled to reconstruct the high-energy gamma-ray events. This Compton detection technique was initially developed to observe gamma rays for astrophysical purposes. A device illustrating the method was designed and adapted to Hadron Therapy Imaging (HTI). It consists of two main sub-systems: a tracker where Compton recoiled electrons are measured, and a calorimeter where the scattered gamma rays are absorbed via the photoelectric effect. Considering a hadron therapy scenario, the analysis of generated data was performed, passing trough the complete detection chain from Monte Carlo simulations to reconstruction of individual events, and finally to image reconstruction. A list-mode Maximum-Likelihood Expectation-Maximization (MLEM) algorithm was adopted to perform image reconstruction in conjunction with the imaging response, which has to depict the complex behavior of the detector. Modeling the imaging response requires complex calculations, considering the incident angle, all measured energies, the Compton scatter angle in the first interaction, the direction of scattered electron (when measured). In the simplest form, each event response is described by Compton cone profiles. The shapes of the profiles are approximated by 1D Gaussian distributions. A strong correlation was observed between pattern of the reconstructed high-energy gamma events, and location of the Bragg peak. The performance of the imaging technique illustrated by the HTI is a function of the detector performance in terms of detection efficiency, spatial and energy resolution, acquisition time, and the algorithms used to reconstruct the gamma-ray activity. Thus beside optimizations of the imaging system, the applied imaging algorithm has a high influence on the final reconstructed images. The HTI reconstructed images are corrupted by noise due to the low photon counts recorded, the uncertainties induced by finite energy resolution, Doppler broadening, the limited model used to estimate the imaging response, and the artifacts generated when iterating the MLEM algorithm. This noise is spatially varying and signal-dependent, representing a major obstacle for information extraction. Thus image de-noising techniques were investigated. AWavelet based multi-resolution strategy of list-mode MLEMRegularization (WREM) was developed to reconstruct Compton images. At each iteration, a threshold-based processing step was integrated. The noise variance was estimated at each scale of the wavelet decomposition as the median value of the coefficients from the high-frequency sub-bands. This approach allowed to obtain a stable behavior of the iterative algorithm, presenting lower mean-squared error, and improved contrast recovery ratioUne nouvelle technique de radiothérapie, l’hadronthérapie, irradie les tumeurs à l’aide d’un faisceau de protons ou d’ions carbone. L’hadronthérapie est très efficace pour le traitement du cancer car elle permet le dépôt d’une dose létale très localisée, en un point dit ’pic de Bragg’, à la fin du trajet des particules. La connaissance de la position du pic de Bragg, avec une précision millimétrique, est essentielle car l’hadronthérapie a prouvé son efficacité dans le traitement des tumeurs profondes, près des organes vitaux, ou radio-résistantes. Un enjeu majeur de l’hadronthérapie est le contrôle de la délivrance de la dose pendant l’irradiation. Actuellement, les centres de traitement par hadronthérapie effectuent un contrôle post-thérapeutique par tomographie par émission de positron (TEP). Les rayons gamma utilisés proviennent de l’annihilation de positons émis lors la désintégration bêta des isotopes radioactifs créés par le faisceau de particules. Ils ne sont pas en coïncidence directe avec le pic de Bragg. Une alternative est l’imagerie des rayons gamma nucléaires émis suites aux interactions inélastiques des hadrons avec les noyaux des tissus. Cette émission est isotrope, présentant un spectre à haute énergie allant de 100 keV à 20 MeV. La mesure de ces rayons gamma énergétiques dépasse la capacité des systèmes d’imagerie médicale existants. Une technique avancée de détection des rayons gamma est proposée. Elle est basée sur la diffusion Compton avec possibilité de poursuite des électrons diffusés. Cette technique de détection Compton a été initialement appliquée pour observer les rayons gamma en astrophysique (télescope Compton). Un dispositif, inspiré de cette technique, a été modélisé avec une géométrie adaptée à l’Imagerie en HadronThérapie (IHT). Il se compose d’un diffuseur, où les électrons Compton sont mesurés et suivis (’tracker’), et d’un calorimètre, où les rayons gamma sont absorbés par effet photoélectrique. Un scénario d’hadronthérapie a été simulé par la méthode de Monte-Carlo, en suivant la chaîne complète de détection, de la reconstruction d’événements individuels jusqu’à la reconstruction d’images de la source de rayons gamma. L’algorithme ’Expectation Maximisation’ (EM) à été adopté dans le calcul de l’estimateur du maximum de vraisemblance (MLEM) en mode liste pour effectuer la reconstruction d’images. Il prend en compte la réponse du système d’imagerie qui décrit le comportement complexe du détecteur. La modélisation de cette réponse nécessite des calculs complexes, en fonction de l’angle d’incidence de tous les photons détectés, de l’angle Compton dans le diffuseur et de la direction des électrons diffusés. Dans sa forme la plus simple, la réponse du système à un événement est décrite par une conique, intersection du cône Compton et du plan dans lequel l’image est reconstruite. Une forte corrélation a été observée entre l’image de la source gamma reconstruite et la position du pic de Bragg. Les performances du système IHT dépendent du détecteur, en termes d’efficacité de détection, de résolution spatiale et énergétique, du temps d’acquisition et de l’algorithme utilisé pour reconstituer l’activité de la source de rayons gamma. L’algorithme de reconstruction de l’image a une importance fondamentale. En raison du faible nombre de photons mesurés (statistique de Poisson), des incertitudes induites par la résolution finie en énergie, de l’effet Doppler, des dimensions limitées et des artefacts générés par l’algorithme itératif MLEM, les images IHT reconstruites sont affectées d’artefacts que l’on regroupe sous le terme ’bruit’. Ce bruit est variable dans l’espace et dépend du signal, ce qui représente un obstacle majeur pour l’extraction d’information. Ainsi des techniques de dé-bruitage ont été utilisées. Une stratégie de régularisation de l’algorithme MLEM (WREM) en mode liste a été développée et appliquée pour reconstituer des images Compton. Cette proposition est multi-résolution sur une base d’ondelettes orthogonales. A chaque itération, une étape de seuillage des coefficients d’ondelettes a été intégrée. La variance du bruit a été estimée à chaque itération par la valeur médiane des coefficients de la sous-bande de haute fréquence. Cette approche stabilise le comportement de l’algorithme itératif, réduit l’erreur quadratique moyenne et améliore le contraste de l’image
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Fontana, Cristiano Lino. "An Imaging Camera for Biomedical Application Based on Compton Scattering of Gamma Rays." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3423412.
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In this thesis we present the R&D of a Compton Camera (CC) for small object imaging.
The CC concept requires two detectors to obtain the incoming direction of the gamma ray.
This approach, sometimes named ``Electronic Collimation,'' differs from the usual technique that employs collimators for physically selecting gamma-rays of a given direction.
This solution offers the advantage of much greater sensitivity and hence smaller doses.
We propose a novel design, which uses two similar Position Sensitive Photomultipliers (Hamamatsu 8500) coupled to different scintillators (one plastic and one inorganic).
Assets of just one kind of detector are the simplicity of design and operation.
Along the experimental apparatus we present our original algorithm for image reconstruction, that was tested with a Geant4 Monte Carlo code.
Employed on experimental data, we obtained a resolution of 6 mm, which is suitable for small animal imaging (such as rats or rabbits) and for small human organs imaging (thyroid and prostate).
The prototype was designed to be a compact modular element that can be extended placing more similar detectors side by sideIn questa tesi presentiamo il lavoro di ricerca e sviluppo di una Camera Compton (CC) per imaging di piccoli oggetti. Le CC richiedono l'utilizzo di due rivelatori per ottenere la direzione d'incidenza di raggi gamma. Questo approccio, talvolta chiamato ``Collimazione Elettronica,'' si differenzia dalle tecniche usuali che utilizzano collimatori per selezionare fisicamente i raggi gamma di una certa direzione. Questa soluzione offre il vantaggio di una sensibilità maggiore e quindi di dosi inferiori. Proponiamo qui un nuovo sistema, che usa due similari Fotomoltiplicatori sensibili alla posizione (Hamamatsu 8500) accoppiati a differenti scintillatori (uno in plastica ed uno inorganico). Avere un solo tipo di rivelatore comporta una maggiore semplicità di progettazione ed utilizzo. Assieme all'apparato sperimentale, presentiamo il nostro algoritmo originale per la ricostruzione d'immagini, che è stato testato con un codice Monte Carlo scritto con Geant4. Applicando l'algoritmo ai dati sperimentali, abbiamo ottenuto una risoluzione di 6 mm, che è adatta all'imaging di piccoli animali (quali ratti e conigli) e per piccoli organi umani (tiroide e prostata). Il prototipo è stato sviluppato per per essere un elemento modulare compatto, che può essere esteso affiancando altri rivelatori simili
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Livieratos-Petratos, George N. "Neural networks for computer aided diagnosis of pulmonary images in nuclear medicine." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295017.
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Brasse, David. "Detection en coincidence des photons de 511 kev provenant de l'annihilation des positons sur gamma-camera conventionnelle : optimisation et analyse des potentialites." Paris 5, 1999. http://www.theses.fr/1999PA05N148.
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Sawano, Tatsuya. "Simulation Study on an Electron-Tracking Compton Camera for Deep Gamma-ray Burst Search." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225397.
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Richard, Marie-Hélène. "Design study of a Compton camera for prompts-gamma imaging during ion beam therapy." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00934715.
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Ion beam therapy is an innovative radiotherapy technique using mainly carbon ion and proton irradiations. Its aim is to improve the current treatment modalities. Because of the sharpness of the dose distributions, a control of the dose if possible in real time is highly desirable. A possibility is to detect the prompt gamma rays emitted subsequently to the nuclear fragmentations occurring during the treatment of the patient. In a first time two different Compton cameras (double and single scattering) have been optimised by means of Monte Carlo simulations. The response of the camera to a photon point source with a realistic energy spectrum was studied. Then, the response of the camera to the irradiation of a water phantom by a proton beam was simulated. It was first compared with measurement performed with small-size detectors. Then, using the previous measurements, we evaluated the counting rates expected in clinical conditions. In the current set-up of the camera, these counting rates are pretty high. Pile up and random coincidences will be problematic. Finally we demonstrate that the detection system is capable to detect a longitudinal shift in the Bragg peak of +or- 5 mm, even with the current reconstruction algorithm.
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Greene, Carmen M. "Experience using a small field of view gamma camera for intraoperative sentinel lymph node procedures." Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-01132006-160335/.
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Smeets, Julien. "Prompt gamma imaging with a slit camera for real time range control in particle therapy." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209624.
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In a growing number of cutting edge centres around the world, radiotherapy treatments delivered by beams of protons and carbon ions offer the opportunity to target tumours with unprecedented conformality. But a sharper dose distribution increases the need for efficient quality control. Treatments are still affected by uncertainties on the penetration depth of the beam within the patient, requiring medical physicists to add safety margins. To reduce these margins and deliver safer treatments, different projects investigate real time range control by imaging prompt gammas emitted along the proton or carbon ion tracks in the patient.This thesis reports on the feasibility, development and test of a new type of prompt gamma camera for proton therapy. This concept uses a knife-edge slit collimator to obtain a 1-dimensional projection of the beam path on a gamma camera. It was optimized, using the Monte Carlo code MCNPX version 2.5.0, to select high energy photons correlated with the beam range and detect them with both high counting statistics and sufficient spatial resolution for use in clinical routine. To validate the Monte Carlo model, spectrometry measurements of secondary particles emitted by a PMMA target during proton irradiation at 160 MeV were realised. An excellent agreement with the simulations was observed when using subtraction methods to isolate the gammas in direct incidence. A first prototype slit camera using the HiCam gamma detector was consequently prepared and tested successfully at 100 and 160 MeV beam energies. If we neglect electronic dead times and rejection of detected events, the current solution with its collimator at 15 cm from beam axis can achieve a 1-2 mm standard deviation on range estimation in a homogeneous PMMA target for numbers of protons that correspond to doses in water at Bragg peak as low as 15 cGy at 100 MeV and 25 cGy at 160 MeV assuming pencil beams with a Gaussian profile of 5 mm sigma at target entrance.
This thesis also investigates the applicability of the slit camera for carbon ion therapy. On the basis of Monte Carlo simulations with the code MCNPX version 2.7.E, this type of camera appears not to be able to identify the beam range with the required sensitivity. The feasibility of prompt gamma imaging itself seems questionable at high beam energies given the weak correlation of secondaries leaving the patient.
This work consequently concludes to the relevance of the slit camera approach for real time range monitoring in proton therapy, but not in carbon ion therapy.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Marzook, Noorul Bishara. "Lights, Camera, Actin: Divergent roles of beta- and gamma-cytoplasmic actin in vaccinia virus infection." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/16859.
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Intracellular pathogens require access to host cells for their replication and spread. The host actin cytoskeleton represents a physical barrier to them, although many have evolved ways to circumvent, or hijack, this system to their advantage. Vaccinia virus (VACV) can manipulate the host actin cytoskeleton to facilitate dissemination. It expedites its cellular egress by nucleating actin beneath its particles, creating filamentous actin (F-actin) comets that propel virions across the cell surface. Tagging VACV proteins with fluorescent markers is used to study virus-host interactions, and define host molecular mechanisms, particularly within dynamic actin pathways. To this end, we developed a novel, optimised protocol for generating recombinant VACV. We then used this to create a recombinant VACV expressing Lifeact-GFP, a fluorescent marker that can highlight F-actin on infection, enabling live tracking of VACV comets via real-time fluorescence microscopy. F-actin comprises two cytoplasmic isoforms: β- and γ-actin. Despite differing only by four N-terminal amino acids, recent studies outlined their distinct localisations and functions in cell lines and whole organisms. We performed a detailed study of their roles in VACV actin-based motility. Initiation of comet formation appears to have an essential requirement for β-actin. Conversely, speed of virus movement was enhanced when γ-actin was silenced, indicating a moderating effect on the rate of actin polymerisation by this isoform. We aimed to define the site of β-actin dependency for VACV actin-based motility by biochemical pull-down assays. This represents the first investigation of the role of actin isoforms in pathogen motility, implicating the importance of their relative distribution in initiating VACV-induced actin comets. Further studies may underpin the importance of β- over γ-actin in other organisms using actin-based motility, providing a route to curb actin-assisted spread of intracellular pathogens.
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Smrčková, Alena. "Design kardiologické gama kamery." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-319481.
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Tématem této diplomové práce je design kardiologické gama kamery. Hlavním cílem práce je navrhnout originální, vizuálně i ergonomicky vyvážený design pro sedícího či napůl ležícího pacienta s využitím nejnovějších technologií s důrazem na propojení dílčích segmentů v kompaktní celek.
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Zorn, Justus [Verfasser], and Jim [Akademischer Betreuer] Hinton. "Cherenkov Camera and Analysis Development for Highest-Energy Gamma-Ray Astronomy / Justus Zorn ; Betreuer: Jim Hinton." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1202608280/34.
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Zorn, Justus [Verfasser], and James Anthony [Akademischer Betreuer] Hinton. "Cherenkov Camera and Analysis Development for Highest-Energy Gamma-Ray Astronomy / Justus Zorn ; Betreuer: Jim Hinton." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-276144.
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Sain, John David. "Optical modeling, design optimization, and performance analysis of a gamma camera for detection of breast cancer." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279873.
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This dissertation presents the research performed to develop an optical model, improve some design parameters, and analyze the performance of the UA modular gamma camera. Initially we provide a brief background on nuclear medical imaging with scintillation cameras. The key hardware components of a camera are introduced, and some of the fundamental physics involved in the detection of gamma rays is explained. Then we describe a stand-alone modular camera imaging system that was developed to image human breasts in the clinic. The hardware and software components, calibration procedure, and general operation of the system are detailed. We explain the concepts of position estimation and scatter rejection and note how they have been applied to imaging with the UA modular gamma camera. Position estimation uses the output signals of the camera to determine where an incident gamma ray interacted within the camera, and scatter rejection uses the signals to decide whether or not an incident gamma ray underwent scattering prior to being detected by the camera. Then we present an analytical optical model of the UA modular gamma camera. Taking into account physical and optical properties of the camera components, the model performs radiometric calculations to estimate the mean response of the camera to a scintillation event anywhere within the scintillation crystal. The results of several studies using the optical model to test and improve some camera design parameters are reported. Finally, we demonstrate how straightforward signal detection theory can be used to evaluate the performance of a modular gamma camera for the task of detecting signals in noisy backgrounds. Guided by the preliminary design of a dedicated breast imaging system, estimates of how well the UA modular gamma camera can detect lesions within human breasts were generated.
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Komura, Shotaro. "Imaging Polarimeter for a Sub-MeV Gamma-Ray All-sky Survey Using an Electron-tracking Compton Camera." Kyoto University, 2018. http://hdl.handle.net/2433/230989.
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Lojacono, Xavier. "Image reconstruction for Compton camera with application to hadrontherapy." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0126/document.
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La caméra Compton est un dispositif permettant d’imager les sources de rayonnement gamma. Ses avantages sont sa sensibilité (absence de collimateur mécanique) et la possibilité de reconstruire des images 3D avec un dispositif immobile. Elle également adaptée pour des sources à large spectre énergétique. Ce dispositif est un candidat prometteur en médecine nucléaire et en hadronthérapie. Ces travaux, financés par le projet européen ENVISION (European NoVel Imaging Systems for ION therapy) Coopération-FP7, portent sur le développement de méthodes de reconstruction d’images pour la caméra Compton pour la surveillance de la thérapie par ions. Celle-ci nécessite idéalement une reconstruction temps réel avec une précision millimétrique, même si le nombre de données acquises est relativement faible. Nous avons développé des méthodes analytiques et itératives. Leurs performances sont analysées dans le contexte d’acquisitions réalistes (géométrie de la caméra, nombre d’événements). Nous avons développé une méthode analytique de rétroprojection filtrée. Cette méthode est rapide mais nécessite beaucoup de données. Nous avons également développé des méthodes itératives utilisant un algorithme de maximisation de la fonction de vraisemblance. Nous avons proposé un modèle probabiliste pour l’estimation des éléments de la matrice système nécessaire à la reconstruction et nous avons développé différentes approches pour le calcul de ses éléments : l’une néglige les incertitudes de mesure sur l’énergie, l’autre les prend en compte en utilisant une distribution gaussienne. Nous avons étudié une méthode simplifiée utilisant notre modèle probabiliste. Plusieurs reconstructions sont menées à partir de données simulées, obtenues avec Geant4, mais provenant aussi de plusieurs prototypes simulés de caméra Compton proposés par l’Institut de Physique Nucléaire de Lyon (IPNL) et par le Centre de recherche de Dresde-Rossendorf en Allemagne. Les résultats sont prometteurs et des études plus poussées, à partir de données encore plus réalistes, viseront à les confirmerThe Compton camera is a device for imaging gamma radiation sources. The advantages of the system lie in its sensitivity, due to the absence of mechanical collimator, and the possibility of imaging wide energy spectrum sources. These advantages make it a promising candidate for application in hadrontherapy. Funded by the european project ENVISION, FP7-Cooperation Work Program, this work deals with the development of image reconstruction methods for the Compton camera. We developed both analytical and iterative methods in order to reconstruct the source from cone-surface projections. Their performances are analyzed with regards to the context (geometry of the camera, number of events). We developped an analytical method using a Filtered BackProjection (FBP) formulation. This method is fast but really sensitive to the noise. We have also developped iterative methods using a List Mode-Maximum Likelihood Expectation Maximization (LM-MLEM) algorithm. We proposed a new probabilistic model for the computation of the elements of the system matrix and different approaches for the calculation of these elements neglecting or not the measurement uncertainties. We also implemented a simplified method using the probabilistic model we proposed. The novelty of the method also lies on the specific discretization of the cone-surface projections. Several studies are carried out upon the reconstructions of simulated data worked out with Geant4, but also simulated data obtained from several prototypes of Compton cameras under study at the Institut de Physique Nucléaire de Lyon (IPNL) and at the Research Center of Dresden-Rossendorf. Results are promising, and further investigations on more realistic data are to be done
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Feng, Yuemeng. "Modeling and regularization in tomographic reconstruction for Compton camera imaging." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI084.
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La caméra Compton est un dispositif d'imagerie gamma pour la tomographie par émission monophotonique (TEMP). Les améliorations qu’elle pourrait apporter aux applications médicales font l’objet de nombreuses études. Elles dépendent à la fois des développements instrumentaux et des techniques de traitement des données, dont la reconstruction tomographique est une étape-clé. Le but de cette thèse est d’améliorer les performances des algorithmes de reconstruction itératifs calculant le maximum de vraisemblance en mode liste (LM-MLEM). En imagerie avec une caméra Compton, le modèle d’acquisition est basé sur l’intégrale de l’intensité de la source sur des projections coniques. La modélisation des incertitudes de mesure influence fortement le résultat de LM-MLEM. L’une des contributions de cette étude est de montrer qu’un modèle plus précis de l’élargissement Doppler, validé avec la simulation Monte-Carlo, conduit à des images plus quantitatives. Une autre contribution est une méthode de régularisation par contrôle de la variation totale (TV) pour des données distribuées selon une loi de Poisson. La régularisation TV permet d’améliorer fortement la qualité des images pour les acquisitions à faible statistique rencontrées dans les applications de ce type d’imagerie. Nous avons également étudié l’apport de la déconvolution avec la fonction d’étalement du point dans le domaine de l’image, en conjonction avec la régularisation. Cette approche est utilisée pour corriger les effets physiques trop difficile à modéliser dans la fonction de transfert. Toutes les méthodes ont été validées avec des simulations Monte-CarloThe Compton camera is an imaging device for SPECT (Single Particle Emission Computed Tomography) of increased sensitivity compared to the Anger camera as it does not require mechanical collimation. The goal of this thesis is to evaluate the improvements that Compton camera may bring for nuclear medicine applications, depending both on technological developments and data processing techniques, among which the tomographic reconstruction is currently a bottleneck. In Compton camera imaging, the acquisition model is based on the integral of the intensity of the source on conical shapes. Modeling the measurement uncertainties in the system matrix can strongly influence the result of the list mode MLEM iterative reconstruction algorithm. One of the contributions of this study is a more precise model validated by Monte Carlo simulation. Another contribution concerns regularization methods. We developed a total variation denoising algorithm for Poisson distributed data that we introduced in the MLEM reconstruction as a regularization step, which allows to improve the image quality in low-counts experiments. A total variation regularized EM reconstruction with PSF deconvolution in the image space is also proposed for ameliorating the conditioning of the inverse problem and restoring the resolution of reconstructed images. All the proposed methods were validated on Monte Carlo simulation
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Hunter, William Coulis Jason. "Modeling Stochastic Processes in Gamma-Ray Imaging Detectors and Evaluation of a Multi-Anode PMT Scintillation Camera for Use with Maximum-Likelihood Estimation Methods." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/196121.
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Maximum-likelihood estimation or other probabilistic estimation methods are underused in many areas of applied gamma-ray imaging, particularly in biomedicine. In this work, we show how to use our understanding of stochastic processes in a scintillation camera and their effect on signal formation to better estimate gamma-ray interaction parameters such as interaction position or energy.To apply statistical estimation methods, we need an accurate description of the signal statistics as a function of the parameters to be estimated. First, we develop a probability model of the signals conditioned on the parameters to be estimated by carefully examining the signal generation process. Subsequently, the likelihood model is calibrated by measuring signal statistics for an ensemble of events as a function of the estimate parameters.In this work, we investigate the application of ML-estimation methods for three topics. First, we design, build, and evaluate a scintillation camera based on a multi-anode PMT readout for use with ML-estimation techniques. Next, we develop methods for calibrating the response statistics of a thick-detector gamma camera as a function of interaction depth. Finally, we demonstrate the use of ML estimation with a modified clinical Anger camera.
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Ueno, Kazuki. "Development of a Wide Band MeV Gamma-Ray Telescope Based on a Gaseous Time Projection Chamber and a Scintillation Camera." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142365.
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Yang, Qing. "A computational fluid dynamic approach and Monte Carlo simulation of phantom mixing techniques for quality control testing of gamma cameras." Thesis, University of Canterbury. Physics and Astronomy, 2013. http://hdl.handle.net/10092/8742.
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In order to reduce the unnecessary radiation exposure for the clinical personnel, the optimization of procedures in the quality control test of gamma camera was investigated. A significant component of the radiation dose in performing the quality control testing is handling phantoms of radioactivity, especially the mixing to get a uniform activity concentration. Improving the phantom mixing techniques appeared to be a means of reducing radiation dose to personnel. However, this is difficult to perform without a continuous dynamic tomographic acquisition system to study mixing the phantom.
In the first part of this study a computational fluid dynamics model was investigated to simulate the mixing procedure. Mixing techniques of shaking and spinning were simulated using the computational fluid dynamics tool FLUENT. In the second part of this study a Siemens E.Cam gamma camera was simulated using the Monte Carlo software SIMIND. A series of validation experiments demonstrated the reliability of the Monte Carlo simulation. In the third part of this study the simulated the mixing data from FLUENT was used as the source distribution in SIMIND to simulate a tomographic acquisition of the phantom. The planar data from the simulation was reconstructed using filtered back projection to produce a tomographic data set for the activity distribution in the phantom. This completed the simulation routine for phantom mixing and verified the Proof-in-Concept that the phantom mixing problem can be studied using a combination of computational fluid dynamics and nuclear medicine radiation transport simulations.
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Allanche, Timothé. "Effect of high radiation doses (MGy) on light Emitting Diodes and optical glasses." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSES039.
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Le projet CAMRAD répond à un appel à projets PIA de l’Agence Nationale pour la gestion des Déchets RAdioactifs (ANDRA) en vue de faciliter la gestion des déchets nucléaires, dont le volume va considérablement augmenter avec le démantèlement du parc nucléaire français. Celui-ci prévoit la conception d’une caméra à Haute Définition durcie aux radiations à des doses au moins dix fois supérieures aux caméras actuellement disponibles. Cette thèse porte sur les effets des rayonnements (jusqu’au MGy) sur les LEDs rendant la caméra autonome en termes de lumière et les verres optiques nécessaires à la réalisation de son système optique. Après une description du projet, les besoins en termes d’éclairage sont détaillés. Les principales innovations de ce travail sont la qualification au MGy de nombreuses LEDs commerciales, des mesures post-irradiation de leurs angles d’émission et des mesures en ligne sous rayon-X. La troisième partie concerne les verres optiques sous radiation. Après avoir détaillé comment le dopage au cérium des verres dits « durci » les protège contre le noircissement causé par les radiations, nous montrons qu’il existe un manque dans la littérature sur les effets des fortes doses. Pour le combler et améliorer les mesures d’atténuation induites, nous avons développé un montage optique permettant de mesurer le noircissement des verres pendant l’irradiation plutôt qu’a posteriori. Il nous a permis de réaliser des mesures systématiques sur des verres durcis et standards en fonction du débit de dose et de la température. Ainsi nous avons montré que certains verres standards présentent un fort potentiel pour une utilisation à des doses de radiations de l’ordre du MGy. L’approche suivie a mené au dépôt d’un brevetThe CAMRAD project responds to the PIA call for proposals from the French National Agency for Radioactive Waste Management with the aim of finding new solutions for radioactive waste management in prevision of its strong increase due to the dismantling of the current French nuclear facilities. The project aims to design a high-definition, radiation-hardened, camera capable to withstand radiation dose levels at least ten times higher than the currently available cameras. This PhD thesis deals with the effects of radiation (up to the MGy) on LEDs allowing the camera to be autonomous in terms of lightning and the optical glasses to be used for the realization of optical system. After a description of CAMRAD, the requirement in terms of lighting are detailed. The main innovations of this work are the qualification at the MGy level of numerous commercial LEDs, post-irradiation measurements of their emission angles and online X-ray measurements. The third part concerns radiation effect on optical glasses. After detailing how Cerium doping of so-called "hardened" glasses protects them from darkening under radiation, we show that there is a lack of literature on the effects of high doses. In order to fill it and to improve the radiation induced attenuation measurements, we have developed an optical set-up allowing to measure the darkening of glasses during irradiation rather than post mortem. We carried systematic measurements on hardened and standard glasses as a function of dose rate and temperature. We have shown that certain standard optical glasses are highly promising for use at MGy dose levels, the followed approach has led to the filing of a patent
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Jones, Martin. "The development of a Compton camera for the imaging of gamma rays in the energy range 0.662 MeV to 6.130 MeV." Thesis, University of Liverpool, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.632425.
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Experimental and GEANT4 simulated Compton camera images and results are presented. This thesis aims to assess the contrasting performance of two seperate detector configurations which include a two germanium Compton camera (GeGe) and a germanium caesium iodide (GeCsI) Compton camera. GEANT4 software has previously been validated. All images were reconstructed using an existsing image reconstruction algorithm which utilises a simple back projection method.
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Trezza, Maicol. "Imaging medico-nucleare: Principi di funzionamento e campi applicativi." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/6989/.
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Takada, Atsushi. "Development of advanced Compton imaging camera with gaseous electron tracker and first flight of sub-MeV gamma-ray imaging loaded-on-balloon experiment." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/73213.
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Blue, Randall Eric. "Targeting the Sodium Iodide Symporter for in Vivo Detection and Characterization of Mammary Tumors in the Murine Model using a Novel Gamma Camera." W&M ScholarWorks, 2009. https://scholarworks.wm.edu/etd/1539626885.
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