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Guy, Matthew John. "The application of quantitative single emission tomography." Thesis, Institute of Cancer Research (University Of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326266.
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Aly, Moamen. "The application of positron emission tomography in radiotherapy treatment planning." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/the-application-of-positron-emission-tomography-in-radiotherapy-treatment-planning(23a8d56c-c6da-4e3f-a27e-6ecbc979c86e).html.
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Positron emission tomography (PET) is a molecular imaging technique that provides a direct and accurate evaluation of tissue function in vivo. PET of the glucose analogue 18F-fluoro-deoxy-glucose, is increasingly in use to aid in gross target volume delineation in radiotherapy treatment planning (RTP) where it shows reduced inter-observer variability. The aim of this thesis was to develop and investigate a new technique for delineating PET-GTV with sufficient accuracy for RTP. A new technique, volume and contrast adjusted thresholding (VCAT), has been developed to automatically determine the optimum threshold value that measures the true volume on PET images. The accuracy was investigated in spherical and irregular lesions in phantoms using both iterative and filtered back-projection reconstructions and different image noise levels. The accuracy of delineation for the irregular lesions was assessed by comparison with CT using the Dice Similarity Coefficient and Euclidean Distance Transformation. A preliminarily investigation of implementing the newly developed technique in patients was carried out. VCAT proved to determine volumes and delineate tumour boundaries on PET/CT well within the acceptable errors for radiotherapy treatment planning irrespective of lesion contrast, image noise level and reconstruction technique.
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Persson, Daniel. "Application of GEANT4 toolkit for simulations of high gradient phenomena." Thesis, Uppsala universitet, FREIA, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353347.
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To study electron emissions and dark currents in the accelerating structures in particle colliders, a test facility with a spectrometer has been constructed at CERN. This spectrometer has been simulated in the C++ toolkit GEANT4 and in this project the simulation has been improved to handle new realistic input data of the emitted electrons. The goal was to find relations between where the electrons are emitted inside the accelerating structure and the energy or position of the particles measured by the spectrometer. The result was that there is a linear relation between the initial position of the electrons and the width in the positions of the particles measured by the spectrometer. It also appears to be a relations between energy the emitted electrons get in the accelerating structure, which is related to the position, and the energy they deposit in the spectrometer. Further studies where the simulations are compared with real measurement data are required to determine whether these relations are true or not, find better reliability in the relations and get a better understanding of the phenomena.
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Maguire, Ralph Paul. "Application of pharmacokinetic models to projection data in positron emission tomography." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/844467/.
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In positron emission tomography (PET), coincidence detection of annihilation photons enables the measurement of Radon transforms of the instantaneous activity concentration of labelled tracers in the human body. Using reconstruction algorithms, spatial maps of the activity distribution can be created and analysed to reveal the pharmacokinetics of the labelled tracer. This thesis considers the possibility of applying pharmacokinetic modelling to the count rate data measured by the detectors, rather than reconstructed images, A new concept is proposed - parameter projections - Radon transforms of the spatial distribution of the parameters of the model, which simplifies the problem considerably. Using this idea, a general linear least squares GLLS framework is developed and applied to the one and two tissue-compartment models for [O-15]water and [F-18]FDG. Simulation models are developed from first principles to demonstrate the accuracy of the GLLS approach to parameter estimation. This requires the validation of the whole body distribution of each of the tracers, using pharmacokinetic techniques, leading to novel compartment based whole body models for [O-15]water and [F-18]FDG. A simplified Monte-Carlo framework for error estimation of the tissue models is developed, based on system parameters. It is also shown that the variances of maps of the spatial variance of the parameters of the model - parametric images - can be calculated in projection space. It is clearly demonstrated that the precision of the variance estimates is higher than that obtained from estimates based on reconstructed images. Using the methods, it is shown how statistical parametric maps of the difference between two neuronal activation conditions can be calculated from projection data. The methods developed allow faster results analysis, avoiding lengthy reconstruction of large data sets, and allow access to robust statistical techniques for activation analysis through use of the known, Poisson distributed nature, of the measured projection data.
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Cree, Michael J. "The Compton Scattering Camera in application to single photon emission computed tomography." Thesis, University of Canterbury. Electrical and Electronic Engineering, 1994. http://hdl.handle.net/10092/6756.
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A study of the Compton Scattering Camera in application to single photon emission computed tomography has been carried out and is presented in this thesis. It is shown that conventional gamma camera technology is fundamentally restricted by the collimator. The collimator places restrictions on camera sensitivity and on achievable reconstructed spatial resolution. The Compton scattering camera is proposed as an alternative to conventional gamma camera technology. The Compton scattering camera uses the process of Compton scattering to determine where a photon has come from. This results in a significant improvement to camera sensitivity and opens up the potential for improved spatial resolving power. An analytical model describing the Compton scattering camera is applied and studied. Suggestions are made regarding the design of a practical camera. It is shown that while a significant gain in sensitivity is achieved by the use of the alternative camera, many more measurement data bins are generated. The latter leads to poor photon counts in each data bin in situations encountered in practical medical imaging. Suggestions are made as to how to combat this problem.
The use of Compton scattering to localise a photon direction vector leads to a new and complicated image reconstruction problem. Iterative algorithms have been devised for the image reconstruction by others and are reviewed herein. Progress towards developing a theory of direct image reconstruction is reported. To this end the notion of the cone-surface projection is introduced. It is shown that a certain subset of data, namely the restricted cone-surface projection, is invertible leading to a formula giving the source distribution in terms of the projections. Hence, the reconstruction problem, in the absence of noise uncertainties, is overspecified. Two possible reconstruction paths are outlined. One is direct reconstruction based on the restricted cone-surface projections. The other forms the cone-beam projections from the cone-surface projections and employs standard cone-beam reconstruction. Results of computer simulation of the reconstruction paths are reported. The direct reconstruction is robust with respect to some angular uncertainty and missing low angle scattering. The formation of the parallel-ray projection from the restricted cone-surface projection appears to be adversely susceptible to such measurement uncertainty. These studies are carried out without accounting for photon noise. For the algorithms to be practically useful, it is necessary that the theorems relating to the restricted cone-surface projection be generalised to cover the full cone-surface projection. Suggestions as to how this may be done are given.
To perform the direct reconstruction from the restricted cone-surface projection. it is necessary to numerically evaluate the Hankel transform. The literature on Hankel transform algorithms is somewhat fragmented; a review of Hankel transform algorithms is therefore presented. Results of testing of a variety of zero-order Hankel transform algorithms are reported. It is found that algorithms based on the trapezoidal rule and the back-projection method with Fourier interpolation lead to the most accurate Hankel transforms in general. Unfortunately these algorithms are relatively computationally expensive. More efficient algorithms, such as the projection-slice method with Hansen and Law's method of evaluating the Abel transform, may be suitable in applications where less accuracy can be tolerated.
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Aryal, Bijaya. "Transfer of learning with an application to the physics of positron emission tomography." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/351.
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Mills, J. A. "Theory of longitudinal emission computed tomography and the practical application to cardiac imaging." Thesis, University of Warwick, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383293.
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Dunkley, Paul. "The investigation and application of OET (Optical Emission Tomography) as a combustion diagnostic." Thesis, University of Warwick, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403115.
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Link, Jeanne Meyers. "Mixed-mode chromatographic separation and whole column radiation detection to improve sensitivity in radiometabolite analysis : application to (Carbon-11)-meta-hydroxyephedrine in plasma /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8578.
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Yu, Haiming. "Analog ASICs for a Depth of Interaction (DOI) Positron Emission Tomography (PET) dectector module /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/6066.
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Alaamer, Abdulaziz. "Quantification in single photon emission computed tomography and its application to targeted radiotherapy and dosimetry." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296162.
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Fuin, N. "Estimation of the image quality in emission tomography : application to optimization of SPECT system design." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1417803/.
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In Emission Tomography the design of the Imaging System has a great influence on the quality of the output image. Optimisation of the system design is a difficult problem due to the computational complexity and to the challenges in its mathematical formulation. In order to compare different system designs, an efficient and effective method to calculate the Image Quality is needed. In this thesis the statistical and deterministic methods for the calculation of the uncertainty in the reconstruction are presented. In the deterministic case, the Fisher Information Matrix (FIM) formalism can be employed to characterize such uncertainty. Unfortunately, computing, storing and inverting the FIM is not feasible with 3D imaging systems. In order to tackle the problem of the computational load in calculating the inverse of the FIM a novel approximation, that relies on a sub-sampling of the FIM, is proposed. The FIM is calculated over a subset of voxels arranged in a grid that covers the whole volume. This formulation reduces the computational complexity in inverting the FIM but nevertheless accounts for the global interdependence between the variables, for the acquisition geometry and for the object dependency. Using this approach, the noise properties as a function of the system geometry parameterisation were investigated for three different cases. In the first study, the design of a parallel-hole collimator for SPECT is optimised. The new method can be applied to evaluating problems like trading-off collimator resolution and sensitivity. In the second study, the reconstructed image quality was evaluated in the case of truncated projection data; showing how the subsampling approach is very accurate for evaluating the effects of missing data. Finally, the noise properties of a D-SPECT system were studied for varying acquisition protocols; showing how the new method is well-suited to problems like optimising adaptive data sampling schemes.
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Lau, Yiu Hon. "Application of joint intensity algorithms to the registration of emission topography and anatomical images /." Electronic version, 2004. http://adt.lib.uts.edu.au/public/adt-NTSM20040901.094913/index.html.
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Cluckie, Alice Jane. "Development and application of an automated analysis method for individual cerebral perfusion single photon emission tomography images." Thesis, King's College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249675.
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Vafaee, Manouchehr S. "Aerobic glycolysis in response to visual stimulation studied by positron emission tomography (PET) : preliminary application to mitochondrial disorders." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0018/NQ55389.pdf.
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Yunusa, Garba Haruna. "Assessment of the impact of the application single photon emission computerized tomography and SPECT-CT on lesion catergorization." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16777.
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Includes bibliographical referencesObjectives: To assess initial experience with the use of a new SPECT-CT in the evaluation of lesions. Methods: The folder number, radiopharmaceutical used and type of scan of patients examined with a new Siemens T6 SPECT-CT between 2 April and 31 December 2013 were retrieved. The number of 99m Tc -MDP bone scans was sufficient for a detailed analysis. The scans were re-processed and reported by the observer before he was given any clinical information. Whole body planar, whole body planar plus SPECT and whole body planar plus SPECT-CT images were assessed successively in three separate sessions at least two weeks apart. At each session, the certainties of detection, localisation, and categorisation of each lesion were recorded. Results: A total of 539 lesions were seen on the whole body, SPECT and CT images in 133 patients. The whole body images showed no lesions in three patients and 378 lesions in 130 patients, 117(31%) lesions in areas not covered by the SPECT. SPECT detected 122 additional lesions in 79 patients. Thirty-nine (12.2%) lesions were seen only on CT in 32 (24.1%) patients. F or the 261 lesions seen on the planar images in the SPECT FOV, lesion detection was definite in 233 (89.3%), localisation definite in 151(57.9%) and categorisation definite in 123 (47.1%) lesions. On the SPECT, definite lesion detection, localisation and categorisation were recorded respectively for 259 (99.2%), 228 (87.4%) and 176 (67.4%) of the 261 lesions. Lesion detection, localisation and categorisation certainties were definite for 100%, 99.1% and 94.7% of the SPECT-CT lesions respectively. Conclusion: Whole body planar scintigraphy is essential in lesion detection. SPECT markedly improves lesion detection and localisation and CT enhances lesion categorisation.
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Ahmadi, Ali. "Application of Collagen Matrices for Enhancing Cardiac Regeneration." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31342.
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Injectable biomaterials have emerged as a treatment for myocardial infarction (MI). They can be applied either as an enhancement for cell therapy or as a stand-alone treatment for MI. The main focus of this study was to apply circulating angiogenic cells (CACs) with or without an injectable collagen matrix for MI treatment in a mouse model. Furthermore, a collagen-chitosan matrix was tested for modulating the myocardial maladaptive remodeling post-MI. First, the in vivo thermo-gelling and retention properties of the collagen matrix were validated using positron emission tomography (PET) tracer and quantum dot (Qdot) labelled matrix in MI mouse hearts. The therapeutic potential of the matrix ± CACs was then tested in a mouse MI model. The results showed that CACs-only and matrix-only treatments were associated with cardiac function preservation. However, in combination, CAC + matrix therapy had a synergistic effect and significantly improved cardiac function (echocardiography), perfusion and viability (PET scan), increased cell engraftment and arteriole density, and reduced the infarct size. CAC-matrix interaction through the integrin alpha2 receptor was essential for the observed therapeutic effect. In a third study, the addition of chitosan (a polysaccharide) to the collagen matrix was shown to reduce maladaptive remodeling post-MI by limiting cardiac fibroblast-to-myofibroblast differentiation and scar formation. In conclusion, these collagen-based hydrogels hold promise to enhance cardiac repair as a delivery scaffold for therapeutic cells, and/or as a stand-alone treatment, which can actively modulate the environment including the fibrotic process after MI.
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Visser, Thomas Jakob. "Development of new muscarinic and [beta]-adrenergic receptor radiopharmaceuticals for Positron Emission Tomography application to lungs, heart and brain /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1997. http://irs.ub.rug.nl/ppn/297496689.
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Wilczek, Brigitte. "Application of nuclear medicine methods in patients with breast cancer /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-340-X/.
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Thomas, Adam J. "Characterization of cAMP-Specific Phosphodiesterase-4 (R)-[11C]Rolipram Small Animal Positron Emission Tomography and Application in a Streptozotocin-Induced Model of Hyperglycemia." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19877.
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Elevated sympathetic nervous system (SNS) tone contributes to excess cardiac mortality associated with type 2 diabetes mellitus (T2DM). Chronic SNS stimulation has detrimental effects to the heart, in particular, with its cell signaling abilities. (R)-[11C]Rolipram small animal positron emission tomography (PET), an noninvasive nuclear imaging modality, was used to assess phosphodiesterase-4 (PDE4) alterations in a high fat diet (HFD), streptozotocin (STZ) induced model of hyperglycemia in rats. Prior to investigation in the animal model, characterization of (R)-[11C]rolipram small animal PET was completed. (R)-[11C]Rolipram binds specifically to PDE4 in the rat heart demonstrated by competitive blockade with (R)-rolipram with the PDE4 enzyme susceptible to saturation with increasing injected masses of unlabeled rolipram. (R)-[11C]Rolipram cardiac retention was elevated by acute norepinephrine stimulation via desipramine pharmacologic challenge. Quantitative (R)-[11C]rolipram PET was highly reproducible in the heart and presents an ideal avenue to investigate PDE4 alterations. (R)-[11C]rolipram small animal PET did not reveal changes in PDE4 expression and activity in STZ-treated hyperglycemic animals compared to STZ-treated euglycemic and control groups. In vitro measures of PDE4 enzyme expression and activity, with or without desipramine, were also not altered between treatment groups. Although (R)-[11C]rolipram small animal PET does not reveal PDE4 alterations in this animal model of diabetes, its utility to assess PDE4 alterations in other over active SNS pathologies, such as heart failure and obesity, remains.
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Tadday, Klaus Alexander [Verfasser], and Hans-Christian [Akademischer Betreuer] Schultz-Coulon. "Scintillation Light Detection and Application of Silicon Photomultipliers in Imaging Calorimetry and Positron Emission Tomography / Klaus Alexander Tadday ; Betreuer: Hans-Christian Schultz-Coulon." Heidelberg : Universitätsbibliothek Heidelberg, 2011. http://d-nb.info/1179783301/34.
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Cselényi, Zsolt. "Development, validation and application of advanced neuroimaging analysis tools for in vivo neuroreceptor studies /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-261-6/.
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Handa, Nobuhiro. "Quantitative myocardial FDG uptake by positron emission tomography in rat heart and its application for longitudinal multiple studies in progressive hypertrophy of heart model." Kyoto University, 2008. http://hdl.handle.net/2433/135924.
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Velikyan, Irina. "Synthesis, Characterisation and Application of 68Ga-labelled Macromolecules." Doctoral thesis, Uppsala universitet, Kemiska institutionen, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5876.
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The positron emitting radionuclide 68Ga (T1/2 = 68 min) might become of practical interest for clinical positron emission tomography (PET). The metallic cation, 68Ga(III), is suitable for complexation with chelators, either naked or conjugated with biological macromolecules. Such labelling procedures require pure and concentrated preparations of 68Ga(III), which cannot be sufficiently fulfilled by the presently available 68Ge/68Ga generator eluate. This thesis presents methods to increase the concentration and purity of 68Ga obtained from a commercial 68Ge/68Ga generator. The use of the preconcentrated and purified 68Ga eluate along with microwave heating allowed quantitative 68Ga-labelling of peptide conjugates within 15 min. The specific radioactivity of the radiolabelled peptides was improved considerably compared to previously applied techniques using non-treated generator eluate and conventional heating. A commercial 68Ge/68Ga generator in combination with the method for preconcentration/purification and microwave heated labelling might result in an automated device for 68Ga-based radiopharmaceutical kit production with quantitative incorporation of 68Ga(III). Macromolecules were labelled with 68Ga(III) either directly or via a chelator. The bifunctional chelator, DOTA, was conjugated in solution to peptides, an antibody and oligonucleotides. The peptides had varied pI values, constitution, and length ranging from 8 to 53 amino acid residues. The oligonucleotides were of various sequences and length with modifications in backbone, sugar moiety and both 3' and 5' ends with a molecular weight up to 9.8 kDa. The bioconjugates were labeled with 68Ga(III), and the resulting tracers were characterised chemically and biologically. The identity of the 68Ga-labelled bioconjugates was verified. The tracers were found to be stable and their biological activity maintained. Specific radioactivity was shown to be an important parameter influencing the feasibility of accurate imaging data quantification. Furthermore, 68Ga-labelled peptide imaging was shown to be a useful tool to study peptide adsorption to microstructures in a chemical analysis device.
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Rohling, Heide. "Simulation studies for the in-vivo dose verification of particle therapy." Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-175213.
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An increasing number of cancer patients is treated with proton beams or other light ion beams which allow to deliver dose precisely to the tumor. However, the depth dose distribution of these particles, which enables this precision, is sensitive to deviations from the treatment plan, as e.g. anatomical changes. Thus, to assure the quality of the treatment, a non-invasive in-vivo dose verification is highly desired. This monitoring of particle therapy relies on the detection of secondary radiation which is produced by interactions between the beam particles and the nuclei of the patient’s tissue.
Up to now, the only clinically applied method for in-vivo dosimetry is Positron Emission Tomography which makes use of the beta+-activity produced during the irradiation (PT-PET). Since from a PT-PET measurement the applied dose cannot be directly deduced, the simulated distribution of beta+-emitting nuclei is used as a basis for the analysis of the measured PT-PET data. Therefore, the reliable modeling of the production rates and the spatial distribution of the beta+-emitters is required. PT-PET applied during instead of after the treatment is referred to as in-beam PET. A challenge concerning in-beam PET is the design of the PET camera, because a standard full-ring scanner is not feasible. For instance, a double-head PET camera is applicable, but low count rates and the limited solid angle coverage can compromise the image quality. For this reason, a detector system which provides a time resolution allowing the incorporation of time-of-flight information (TOF) into the iterative reconstruction algorithm is desired to improve the quality of the reconstructed images.
Secondly, Prompt Gamma Imaging (PGI), a technique based on the detection of prompt gamma-rays, is currently pursued. Concerning the emissions of prompt gamma-rays during particle irradiation, experimental data is not sufficiently available, making simulations necessary. Compton cameras are based on the detection of incoherently scattered photons and are investigated with respect to PGI. Monte Carlo simulations serve for the optimization of the camera design and the evaluation of criteria for the selection of measured events.
Thus, for in-beam PET and PGI dedicated detection systems and, moreover, profound knowledge about the corresponding radiation fields are required. Using various simulation codes, this thesis contributes to the modelling of the beta+-emitters and photons produced during particle irradiation, as well as to the evaluation and optimization of hardware for both techniques.
Concerning the modeling of the production of the relevant beta+-emitters, the abilities of the Monte Carlo simulation code PHITS and of the deterministic, one-dimensional code HIBRAC were assessed. The Monte Carlo tool GEANT4 was applied for an additional comparison. For irradiations with protons, helium, lithium, and carbon, the depth-dependent yields of the simulated beta+-emitters were compared to experimental data. In general, PHITS underestimated the yields of the considered beta+-emitters in contrast to GEANT4 which provided acceptable values. HIBRAC was substantially extended to enable the modeling of the depth-dependent yields of specific nuclides. For proton beams and carbon ion beams HIBRAC can compete with GEANT4 for this application. Since HIBRAC is fast, compact, and easy to modify, it could be a basis for the simulations of the beta+-emitters in clinical application. PHITS was also applied to the modeling of prompt gamma-rays during proton irradiation following an experimental setup. From this study, it can be concluded that PHITS could be an alternative to GEANT4 in this context.
Another aim was the optimization of Compton camera prototypes. GEANT4 simulations were carried out with the focus on detection probabilities and the rate of valid events. Based on the results, the feasibility of a Compton camera setup consisting of a CZT detector and an LSO or BGO detector was confirmed. Several recommendations concerning the design and arrangement of the Compton camera prototype were derived. Furthermore, several promising event selection strategies were evaluated. The GEANT4 simulations were validated by comparing simulated to measured energy depositions in the detector layers. This comparison also led to the reconsideration of the efficiency of the prototype. A further study evaluated if electron-positron pairs resulting from pair productions could be detected with the existing prototype in addition to Compton events. Regarding the efficiency and the achievable angular resolution, the successful application of the considered prototype as pair production camera to the monitoring of particle therapy is questionable.
Finally, the application of a PET camera consisting of Resistive Plate Chambers (RPCs) providing a good time resolution to in-beam PET was discussed. A scintillator-based PET camera based on a commercially available scanner was used as reference. This evaluation included simulations of the detector response, the image reconstructions using various procedures, and the analysis of image quality. Realistic activity distributions based on real treatment plans for carbon ion therapy were used. The low efficiency of the RPC-based PET camera led to images of poor quality. Neither visually nor with the semi-automatic tool YaPET a reliable detectability of range deviations was possible. The incorporation of TOF into the iterative reconstruction algorithm was especially advantageous for the considered RPC-based PET camera in terms of convergence and artifacts.
The application of the real-time capable back projection method Direct TOF for the RPCbased PET camera resulted in an image quality comparable to the one achieved with the iterative algorihms. In total, this study does not indicate the further investigation of RPC-based PET cameras with similar efficiency for in-beam PET application.
To sum up, simulation studies were performed aimed at the progress of in-vivo dosimetry. Regarding the modeling of the beta+-emitter production and prompt gamma-ray emissions, different simulation codes were evaluated. HIBRAC could be a basis for clinical PT-PET simulations, however, a detailed validation of the underlying cross section models is required. Several recommendations for the optimization of a Compton Camera prototype resulted from systematic variations of the setup. Nevertheless, the definite evaluation of the feasibility of a Compton camera for PGI can only be performed by further experiments. For PT-PET, the efficiency of the detector system is the crucial factor. Due to the obtained results for the considered RPC-based PET camera, the focus should be kept to scintillator-based PET cameras for this purpose.
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Velikyan, Irina. "Synthesis, Characterisation and Application of 68Ga-labelled Macromolecules." Doctoral thesis, Uppsala : Acta Universitetis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5876.
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Maingueneau, Clémence. "Valorisation des sultones et boratranes comme plateformes de radiomarquage au fluor-18 : application au développement de radiotraceurs pour l'imagerie de l'hypoxie par Tomographie par Emission de Positons." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC228.
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Les travaux de thèse ont porté sur le développement de deux plateformes de radiomarquage polyvalentes pour faciliter l’incorporation du fluor-18, un isotope de choix pour l’imagerie TEP (Tomographie par Emission de Positons). La première plateforme comporte une structure sultone conduisant à un [18F]fluorosulfonate par ouverture du cycle avec le [18F]fluorure. Celle-ci a été valorisée par le couplage avec des ligands 2-nitroimidazoliques pour former un agent d’imagerie TEP spécifique de l’hypoxie. Une série de dérivés caractérisés par des propriétés d’hydrophilie différentes a été synthétisée afin de comparer leur efficacité en imagerie. Parmi ces dérivés, le [18F]FLUSONIM a révélé dans différents modèles précliniques tumoraux (rhabdomyosarcome, tumeurs cérébrales et mélanome) des ratios tumeur sur bruit de fond inégalés jusqu’à présent, et ce à des temps très précoces post-injection. La deuxième plateforme est de nature boratrane. Celle-ci est capable de réagir avec le [18F]fluorure en milieu physiologique pour former un [18F]monofluoroborate zwitterionique facile à séparer du précurseur boratraneThis work focused on the development of versatile platforms for fluorine-18 labelling. The first platform contained a sultone moiety which was converted to [18F]fluorosulfonate by ring opening with [18F]fluoride. The sultone was coupled to 2-nitroimidazolyl ligands to obtain radiotracers for hypoxia PET imaging. A series of compounds were synthesized in order to compare their performance in PET imaging. Among them, [18F]FLUSONIM displayed high tumor/background ratios after a short delay post-injection on different animal models (rabdomyosarcoma, glioblastoma and melanoma). The second platform was based on a boratrane structure, that was able to captur [18F]fluoride in aqueous medium to form zwiterionic [18F]monofluoroborate
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Henriques, de Figueiredo Bénédicte. "Evaluation de l’integration des donnees issues de la tomographie par emission de positons en radiotherapie : application à deux modèles cliniques : les cancers ORL et les cancers pulmonaires." Thesis, Bordeaux 2, 2013. http://www.theses.fr/2013BOR22125/document.
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Objectif : Etudier l’impact volumétrique et dosimétrique de l’intégration des données de tomographie par émission de positons (TEP) en radiothérapie (RT) à travers deux modèles cliniques : les cancers oto-rhino-laryngologiques (ORL) et les cancers pulmonaires. Matériel et méthodes : Pour les cancers ORL, après un travail préalable sur fantôme pour mise au point d’une méthode de segmentation automatique par seuillage adaptatif, deux séries de neuf et 15 patients présentant un cancer ORL traité par RT, ont bénéficié d’une TEP respectivement au 18F-Fluorodeoxyglucose (18F-FDG) et au 18F-Fluoromisonidazole (18F-FMISO), traceur de l’hypoxie. Les modifications volumétriques et dosimétriques induites par ces examens ont été analysées. Pour le 18F-FMISO, différents temps d’acquisition et différentes méthodes de segmentation ont également été étudiés. Pour les cancers pulmonaires, l’impact sur la RT d’une TEP-4D au 18F-FDG avec correction des effets de volume partiel (EVP) et application de différentes méthodes de segmentation, a été évalué à travers l’analyse des sept premiers patients inclus dans le protocole PULMOTEP, promu par le CHU de Bordeaux. Résultats : Pour les cancers ORL, la TEP au 18F-FDG a conduit à une réduction des volumes de RT de 40% tout en individualisant des zones de « mismatch » entre TEP et scanner. Pour la TEP au 18F-FMISO, un meilleur contraste des images était retrouvé à 4h. Cependant, les volumes segmentés à 3 et 4h n’étaient pas significativement différents, permettant d’envisager en pratique courante des acquisitions moins tardives à 3h. L’utilisation d’une TEP au 18F-FMISO permettait d’envisager la réalisation d’une « escalade de dose » sur les zones hypoxiques avec une augmentation du taux de probabilité de contrôle tumoral de 18,1% sans augmentation excessive de la toxicité. Pour les cancers pulmonaires, il n’était pas retrouvé d’impact de la correction du mouvement respiratoire, un seul patient sur les sept étudiés présentant une tumeur mobile. Un impact constant de la correction des EVP était par contre retrouvé avec une augmentation de l’activité tumorale maximale de 27% et une diminution des volumes segmentés de 15%.Conclusion : Pour les cancers ORL, la validation de ces résultats nécessite la réalisation d’études cliniques. Pour les cancers pulmonaires, l’utilisation d’une TEP-4D avec correction du mouvement respiratoire doit être envisagée au cas par cas. L’implémentation en clinique de logiciels de correction des EVP semble, par contre, à encouragerObjective: To study the impact of Positron Emission Tomography (PET) data on radiotherapy (RT) planning through two clinical models: the head-and-neck cancers (HNC) and the pulmonary cancers. Methods and Materials: For HNC, after a previous phantom study in order to determinate an automatic segmentation method with adaptive thresholding, two series of nine and 15 patients selected for RT, underwent PET with 18F-Fluorodeoxyglucose (FDG) and 18F-Fluoromisonidazole (FMISO). The impact on RT target volumes (TV) and dosimetries was evaluated. For FMISO-PET, several time acquisitions and several segmentation methods were assessed. For pulmonary cancers, the use of a four-dimensional (4D) FDG-PET with partial volume effect (PVE) correction and several segmentation methods was evaluated through the first seven patients enrolled in the PULMOTEP protocol performed by the CHU of Bordeaux. Results: For HNC, FDG-PET led to a RT TV reduction of 40%, with mismatches between PET and CT data. For FMISO-PET images, a better contrast was obtained 4h after FMISO injection. However, segmented volumes obtained at 3 and 4h were not statistically different allowing PET- acquisitions at 3h in routine clinical practice. The use of FMISO-PET allows considering « dose escalation » on hypoxic TV with an increase of tumour control probability by 18,1% without excessive increase of toxicities. For pulmonary cancers, there was no impact of the respiratory motion correction but only one patient on seven presented a mobile tumour. PVE correction had impact on RT TV with an increase of the maximal tumoural activity by 27% and a volume reduction of 15%. Conclusion: For HNC, the validation of these results needs clinical and prospective studies. For pulmonary cancers, the use of 4D-PET must be decided case by case. On the other side, the implementation of automatic software for PVE correction seems interesting
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James, Damien. "Développement d'outils organométalliques en vue du transfert de méthyle, application à la synthèse de radiotraceurs pour la TEP." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13900/document.
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Le couplage de Stille modifié développé par l’équipe du Pr Fouquet a été appliqué à la méthylation de nucléosides, dinucléotides et oligonucléotides dans le but de mettre au point une méthodologie de marquage d’aptamères au carbone 11 pour le diagnostic précoce de cancer par TEP. Ce couplage pallado-catalysé est basé sur l’utilisation de monoorganoétain activé par une source de fluorure permettant d’accélérer la réaction. Dans un premier temps, les essais méthodologiques ont permis de mettre au point le transfert de groupement méthyle sur différents nucléosides et un dinucléotide modifiés dans des conditions compatibles avec la durée de demi-vie du carbone 11 (20,4 min) et la nature particulière des oligonucléotides. Puis, cette méthodologie a été appliquée à des oligonucléotides modèles obtenus après incorporation des nucléosides les plus prometteursThe modified Stille cross-coupling developed by Pr. Fouquet’s group was applied to the methylation of nucleosides, dinucleotides and oligonucleotides in order to develop a methodology for labelling aptamers with carbon 11 for the early diagnosis of cancer by PET. This pallado-catalyzed cross-coupling is based on the use of monoorganotin activated by a source of fluoride accelerating the reaction. Initial methodology tests helped to finalize the transfer of methyl group on various nucleosides and a dinucleotide, with reaction conditions compatible with the short half-life of carbon 11 (20.4 min) and the special nature of oligonucleotides. Then, this methodology was applied to oligonucleotide models obtained after incorporation of the most promising nucleosides
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Travere, Jean-Marcel. "Analyse automatique quantitative en tomographie par emission de positions : application a l'etude de la concentration en recepteurs muscariniques de la paroi ventriculaire gauche." Caen, 1987. http://www.theses.fr/1987CAEN2033.
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Jouvie, Camille. "Estimation de la fonction d’entrée en tomographie par émission de positons dynamique : application au fluorodesoxyglucose." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112303/document.
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La tomographie par émission de positons (TEP) est une méthode d’imagerie fonctionnelle, utilisée en particulier lors du développement de nouveaux médicaments et pour imager les tumeurs. En TEP, l’estimation de la concentration plasmatique artérielle d’activité du traceur non métabolisé (nommée « fonction d’entrée ») est nécessaire pour l’extraction des paramètres pharmacocinétiques. Ceux-ci permettent de quantifier le comportement du traceur dans les tissus, ou plus précisément le traitement du traceur par les tissus. Cette thèse constitue une contribution à l’étude de la fonction d’entrée, par l’élaboration d’une méthode d’estimation de la fonction d’entrée peu invasive à partir des images TEP et de prélèvements veineux. L’exemple du traceur FDG (analogue du glucose) dans le cerveau humain a été choisi. La méthode proposée repose sur la modélisation compartimentale de l’organisme : elle déconvolue le modèle à trois compartiments utilisé pour le FDG. L’originalité de la méthode repose sur trois points : l’utilisation d’un grand nombre de régions d’intérêt ; l’utilisation d’un grand nombre de jeux de trois régions d’intérêt différentes; une estimation itérative. Pour la validation de la méthode, un soin particulier a été porté à la simulation d’images TEP (simulation d’acquisition, reconstruction, corrections) de plus en plus réalistes, depuis une image simple simulée avec un simulateur analytique jusqu’à une image la plus proche possible de la réalité, simulée avec simulateur Monte-Carlo. Une chaîne de pré-traitement (segmentation des IRM associés, recalage entre images TEP et IRM et correction de l’effet de volume partiel par une variante de la méthode de Rousset) a ensuite été appliquée à ces images afin d’extraire les cinétiques des régions d’intérêt, données d’entrée de la méthode d’estimation de la fonction d’entrée. L’évaluation de la méthode sur différentes données, simulées et réelles, est présentée, ainsi que l’étude de la sensibilité de la méthode à différents facteurs tels que les erreurs de segmentation, de recalage, de mesure de l’activité des prélèvements sanguinsPositron Emission Tomography (PET) is a method of functional imaging, used in particular for drug development and tumor imaging. In PET, the estimation of the arterial plasmatic activity concentration of the non-metabolized compound (the "input function") is necessary for the extraction of the pharmacokinetic parameters. These parameters enable the quantification of the compound dynamics in the tissues. This PhD thesis contributes to the study of the input function by the development of a minimally invasive method to estimate the input function. This method uses the PET image and a few blood samples. In this work, the example of the FDG tracer is chosen. The proposed method relies on compartmental modeling: it deconvoluates the three-compartment-model. The originality of the method consists in using a large number of regions of interest (ROIs), a large number of sets of three ROIs, and an iterative process. To validate the method, simulations of PET images of increasing complexity have been performed, from a simple image simulated with an analytic simulator to a complex image simulated with a Monte-Carlo simulator. After simulation of the acquisition, reconstruction and corrections, the images were segmented (through segmentation of an IRM image and registration between PET and IRM images) and corrected for partial volume effect by a variant of Rousset’s method, to obtain the kinetics in the ROIs, which are the input data of the estimation method. The evaluation of the method on simulated and real data is presented, as well as a study of the method robustness to different error sources, for example in the segmentation, in the registration or in the activity of the used blood samples
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Nguyen, Pham Truong. "Imagerie corrélative : autoradiographie - tomographie par émission de positons : application à l’imagerie cérébrale dans le lupus." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAE027.
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L’imagerie nucléaire se révèle essentielle dans le domaine clinique et pré-clinique pour l’étude de la biodistribution du médicament et le suivi de l’évolution de la pathologie. La TEP (Tomographie par Émission de Positons) est aujourd’hui un standard pour l’imagerie fonctionnelle avec une sensibilité de l’ordre du picomole. Elle offre une résolution de l’ordre du millimètre. Dans le cadre de cette thèse, l’autoradiographie, avec des capteurs semi-conducteurs Mimosa-28, permet d’obtenir une résolution sub-millimètre tout en gardant une bonne sensibilité afin de mieux visualiser la distribution cérébrale du radiotraceur chez la souris. Préalablement à une utilisation, ce capteur est caractérisé avec des isotopes habituellement utilisés en préclinique dans le système TEP : 18F, 64Cu et 89Zr. Des mesures d’efficacité et de résolution spatiale sont effectuées afin de comparer par rapport aux autres systèmes actuellement disponibles comme les films à émulsion, la phosphorescence, la scintillation et les détecteurs gazeux. Les examens TEP permet tant d’explorer la biodistribution à l’échelle de l’animal avant de mieux visualiser la distribution avec l’autoradiographie dans un organe spécifique. Nous avons ensuite d’explorer la possibilité d’améliorer la qualité des images grâce à la simulation Monte-Carlo GATE (GEANT4 Application for Tomography Emission) et à la reconstruction via un algorithme MLEM (Maximum Likelihood Estimation Method). Les images autoradiographiques gagnent en contraste et l’effet de la diffusion des particules chargées dans le milieu est atténuéeNuclear imaging is essential in the clinical and pre-clinical field for studying the biodistribution of the drug and observing the evolution of the pathology. Positron Emission Tomography (PET) scan is today a gold standard functional imaging with picomolar sensitivity. It offers a resolution of the order of a millimetre. As part of this thesis, autoradiography, with Mimosa-28 semiconductor sensors, provides a sub-millimetre resolution while keeping a good sensitivity in order to visualize the cerebral distribution of the radiotracer in the mouse. Before the autoradiography acquisition, this sensor is characterized with isotopes usually used in preclinical systems in the PET system : 18F, 64Cu and 89Zr. Measurements of efficiency and spatial resolution are made to compare with other current systems such as emulsion films, phosphorescence, scintillation and gaseous detectors. PET scans enable both to explore biodistribution at the animal scale before to visualize the distribution with autoradiography at the tissue scale. We then explore the possibility of improving the quality of images through GEANT4 Application for Tomography Emission (GATE) Monte-Carlo simulation and reconstruction using a Maximum Likelihood Estimation Method (MLEM) algorithm. The autoradiographic images gain in contrast and the scattering effect of the charged particles into the medium is attenuated
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Irace, Zacharie. "Modélisation statistique et segmentation d'images TEP : application à l'hétérogénéité et au suivi de tumeurs." Phd thesis, Toulouse, INPT, 2014. http://oatao.univ-toulouse.fr/12201/1/irace.pdf.
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Cette thèse étudie le traitement statistique des images TEP. Plus particulièrement, la distribution binomiale négative est proposée pour modéliser l’activité d’une région mono-tissulaire. Cette représentation a l’avantage de pouvoir prendre en compte les variations d’activité biologique (ou hétérogénéité) d’un même tissu. A partir de ces résultats, il est proposé de modéliser la distribution de l’image TEP entière comme un mélange spatialement cohérent de lois binomiales négatives. Des méthodes Bayésiennes sont considérées pour la segmentation d’images TEP et l’estimation conjointe des paramètres du modèle. La cohérence spatiale inhérente aux tissus biologiques est modélisée par un champ aléatoire de Potts-Markov pour représenter la dépendance locale entre les composantes du mélange. Un algorithme original de Monte Carlo par Chaîne de Markov (MCMC) est utilisé, faisant appel aux notions d’échantillonnage dans un espace Riemannien et d’opérateurs proximaux. L’approche proposée est appliquée avec succès à la segmentation de tumeurs en imagerie TEP. Cette méthode est ensuite étendue d’une part en intégrant au processus de segmentation des informations anatomiques acquises par tomodensitométrie (TDM), et d’autre part en traitant une série temporelle d’images correspondant aux différentes phases de respiration. Un modèle de mélange de distributions bivariées binomiale négative - normale est proposé pour représenter les images dynamiques TEP et TDM fusionnées. Un modèle Bayésien hiérarchique a été élaboré comprenant un champ de Potts-Markov à quatre dimensions pour respecter la cohérence spatiale et temporelle des images PET-TDM dynamiques. Le modèle proposé montre une bonne qualité d’ajustement aux données et les résultats de segmentation obtenus sont visuellement en concordance avec les structures anatomiques et permettent la délimitation et le suivi de la tumeur.
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Fall, Mame Diarra. "Modélisation stochastique de processus pharmaco-cinétiques, application à la reconstruction tomographique par émission de positrons (TEP) spatio-temporelle." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112035.
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L'objectif de ce travail est de développer de nouvelles méthodes statistiques de reconstruction d'image spatiale (3D) et spatio-temporelle (3D+t) en Tomographie par Émission de Positons (TEP). Le but est de proposer des méthodes efficaces, capables de reconstruire des images dans un contexte de faibles doses injectées tout en préservant la qualité de l'interprétation. Ainsi, nous avons abordé la reconstruction sous la forme d'un problème inverse spatial et spatio-temporel (à observations ponctuelles) dans un cadre bayésien non paramétrique. La modélisation bayésienne fournit un cadre pour la régularisation du problème inverse mal posé au travers de l'introduction d'une information dite a priori. De plus, elle caractérise les grandeurs à estimer par leur distribution a posteriori, ce qui rend accessible la distribution de l'incertitude associée à la reconstruction. L'approche non paramétrique quant à elle pourvoit la modélisation d'une grande robustesse et d'une grande flexibilité. Notre méthodologie consiste à considérer l'image comme une densité de probabilité dans (pour une reconstruction en k dimensions) et à chercher la solution parmi l'ensemble des densités de probabilité de . La grande dimensionalité des données à manipuler conduit à des estimateurs n'ayant pas de forme explicite. Cela implique l'utilisation de techniques d'approximation pour l'inférence. La plupart de ces techniques sont basées sur les méthodes de Monte-Carlo par chaînes de Markov (MCMC). Dans l'approche bayésienne non paramétrique, nous sommes confrontés à la difficulté majeure de générer aléatoirement des objets de dimension infinie sur un calculateur. Nous avons donc développé une nouvelle méthode d'échantillonnage qui allie à la fois bonnes capacités de mélange et possibilité d'être parallélisé afin de traiter de gros volumes de données. L'approche adoptée nous a permis d'obtenir des reconstructions spatiales 3D sans nécessiter de voxellisation de l'espace, et des reconstructions spatio-temporelles 4D sans discrétisation en amont ni dans l'espace ni dans le temps. De plus, on peut quantifier l'erreur associée à l'estimation statistique au travers des intervalles de crédibilitéThe aim of this work is to develop new statistical methods for spatial (3D) and space-time (3D+t) Positron Emission Tomography (PET) reconstruction. The objective is to propose efficient reconstruction methods in a context of low injected doses while maintaining the quality of the interpretation. We tackle the reconstruction problem as a spatial or a space-time inverse problem for point observations in a \Bayesian nonparametric framework. The Bayesian modeling allows to regularize the ill-posed inverse problem via the introduction of a prior information. Furthermore, by characterizing the unknowns with their posterior distributions, the Bayesian context allows to handle the uncertainty associated to the reconstruction process. Being nonparametric offers a framework for robustness and flexibility to perform the modeling. In the proposed methodology, we view the image to reconstruct as a probability density in(for reconstruction in k dimensions) and seek the solution in the space of whole probability densities in . However, due to the size of the data, posterior estimators are intractable and approximation techniques are needed for posterior inference. Most of these techniques are based on Markov Chain Monte-Carlo methods (MCMC). In the Bayesian nonparametric approach, a major difficulty raises in randomly sampling infinite dimensional objects in a computer. We have developed a new sampling method which combines both good mixing properties and the possibility to be implemented on a parallel computer in order to deal with large data sets. Thanks to the taken approach, we obtain 3D spatial reconstructions without any ad hoc space voxellization and 4D space-time reconstructions without any discretization, neither in space nor in time. Furthermore, one can quantify the error associated to the statistical estimation using the credibility intervals
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Razifar, Pasha. "Novel Approaches for Application of Principal Component Analysis on Dynamic PET Images for Improvement of Image Quality and Clinical Diagnosis." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6053.
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Sihver, Sven. "Development of in vitro and ex vivo positron-emitting tracer techniques and their application to neurotrauma." Doctoral thesis, Uppsala universitet, Institutionen för neurovetenskap, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-485.
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The use of positron-emitting tracers has been extended beyond tomographic facilities in the last few years, giving rise to a general positron-emitting tracing technique. The methodological part of the present thesis involved the evaluation of the performance of storage phosphor (SP) plates, with tracers labeled with high-energy, short-lived, positron-emitting radionuclides, using homogenized tissue specimens and autoradiography with frozen brain sections. The SP plates showed superior sensitivity and a linear response over a wide radioactivity range. Autoradioradiography provided reliable results due to (a) adequate sensitivity for low radioactivity concentration, b) an excellent linear range, and (c) satisfactory resolution. Though equilibration time of receptor-ligand interaction was dependent upon section thickness, quantification was possib with thinner sections. An initial finding using frozen section autoradiography of rat brain and spinal cord showed preferential binding of [11C]4-NMPB, a muscarinic acetylcholine (mACh) receptor antagonist, to the M4 subtype of mACh receptors. Further work to ascertain this specificity, by use of binding studies on cell membranes from CHO-K1 cells expressing individual subtypes of human mACh receptors, suggested lack of subtype selectivity. With respect to the possible cliinical use in glutamatergic neuropathology, [11C]cyano-dizocilpine, as a potential PET tracer for the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors, was studied. The in vivo visualization of specific binding could not be achieved, though in vitro binding demonstrated good specificity and preferential binding to the activated for of the NMDA receptors. The use of the glucose analogue [18F]fluorodeoxyglucose (FDG) to study glucose utilization was evaluated in experimental traumatic brain injury (TBI). A trauma-induced increased uptake of FDG was seen, whereas the uptake of [1-14C]glucose remained unchanged. This discrepancy might be due to the increased postraumatic affinity of FDG for the endothelial glucose transporter proteins and/or to the hexokinase enzyme. [11C]Cyano-dizocilpine, [11C]4-NMPB, and [11C]flumazenil were utilized in autoradiography to evaluate changes in NMDA, mACh, and GABAA receptors, espectively, in experimental TBI. Observations showed a global decrease in the binding potential BP) of (i) [11C]cyano-dizocilpine acutely and 12 hrs after TBI, and (ii) of [11C]4-NMPB at 12 hrs after TBI, and (iii) a decrease in the BP of [11C]flumazenil in the cortex and hippocampus ipsilateral to the site of injury. The demonstrated changes in receptor binding after TBI are indicative of a widely dissipated effect of TBI on the particular neurotransmitter receptor systems as compared with what would be expected from FDG studies after TBI, i.e., a local disturbed neurotransmission.
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Macías, Montero José Gabriel. "VIPPIX: A readout ASIC for the next generation of human brain PET scanners." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663182.
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Positron emission tomography (PET) is a molecular imaging technique used for several decades in nuclear medicine that provides precise physiological information of the human body, what is crucial in oncology, cardiology, and neuropsychiatry. Due to physical, the best spatial resolution of PET is approximately 1 mm for human brain scanners. Unfortunately, the minimum resolution of the best commercial PET scanners for humans is 4-5 mm due to technological limitations.
In this thesis, an application specific integrated circuit (ASIC) to readout the energy and the time stamp of a high-density and highly-granulated Cadmium Telluride detector for a novel PET scanner design is presented. The research presented here was realized within the framework of Voxel Imaging PET pathfinder ERC project to develop detector modules for positron emission tomography applications and reach their actual physical limits.
The VIP PET scanner is based on the stacking of 2-mm thickness pixelated hybrid detectors. Every CdTe detector is pixelated into an array of 10 x 10 voxels of 1 mm x 1 mm x 2 mm size and is connected to a pixelated ASIC to readout independently the energy and the time stamp of every photon interaction. The VIP PET is based on more than 6 million voxels with independent energy and timing readout to reach the physical limits of PET. The simulated performance based on the properties of CdTe detectors shows a scatter fraction of approximately 4 % due to an excellent energy resolution of 1.6 % FWHM of the CdTe detectors. By simulation, the VIP PET is able to distinguish 1 mm size radioactive point-like source.
The characterization of 2-mm thickness CdTe detectors using commercially available single-channel readout electronics is reported. Using a Sodium-22 radioactive source, the 511 keV photopeak resolution and the coincidence time resolution of back-to-back photons were measured with – 1000 V/mm detector bias voltage at -8 Celsius degree. An energy resolution of
1.6 % FWHM and a time coincidence resolution of 6 ns FWHM were obtained for photoelectric interactions.
The architecture of the VIPPIX ASIC, i.e. the ASIC developed for VIP project, is based on an array of 10 x 10 independent pixel electronics controlled by a global controller and a common time to digital converter (TDC). Additional voltage and current references are generated in the ASIC’s back-end with a temperature sensor and a chip-ID cell. Every pixel electronics composes of a programmable gain preamplifier with detector’s leakage dynamic compensation, a tuneable peak-time pulse shaper connected to a peak-and-detect circuit, a 10-bit analog-to- digital converter (ADC), a pulse discriminator with adjustable offset, and a local pixel digital controller. The measured equivalent noise charge (ENC) of the pixel is 150 e- RMS and the trigger time jitter is approximately 1 ns for energy depositions larger than 200 keV. The time resolution of the integrated TDC is 600 ps FWHM.
Twelve wafers of VIPPIX ASIC has been fabricated and characterized. Best quality ASICs have been mounted on 720 CdTe detectors and stacked in 18 detector modules with 40 hybrid detectors each to build the VIP PET prototype. Five modules have been characterized with a Sodium-22 radioactive source. The performance of approximately 18000 pixels shows a resolution of 2.2 % FWHM and a coincidence time resolution of 60 ns FWHM for 511 keV photopeak at -250 V/mm detector bias.
Therefore, the main goal of the research has been accomplished. A new PET design based on pixelated Cadmium Telluride detectors using dedicated readout ASICs has been successfully fabricated, partly characterized, and is ready for image acquisition.
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Lian, Chunfeng. "Information fusion and decision-making using belief functions : application to therapeutic monitoring of cancer." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2333/document.
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La radiothérapie est une des méthodes principales utilisée dans le traitement thérapeutique des tumeurs malignes. Pour améliorer son efficacité, deux problèmes essentiels doivent être soigneusement traités : la prédication fiable des résultats thérapeutiques et la segmentation précise des volumes tumoraux. La tomographie d’émission de positrons au traceur Fluoro- 18-déoxy-glucose (FDG-TEP) peut fournir de manière non invasive des informations significatives sur les activités fonctionnelles des cellules tumorales. Les objectifs de cette thèse sont de proposer: 1) des systèmes fiables pour prédire les résultats du traitement contre le cancer en utilisant principalement des caractéristiques extraites des images FDG-TEP; 2) des algorithmes automatiques pour la segmentation de tumeurs de manière précise en TEP et TEP-TDM. La théorie des fonctions de croyance est choisie dans notre étude pour modéliser et raisonner des connaissances incertaines et imprécises pour des images TEP qui sont bruitées et floues. Dans le cadre des fonctions de croyance, nous proposons une méthode de sélection de caractéristiques de manière parcimonieuse et une méthode d’apprentissage de métriques permettant de rendre les classes bien séparées dans l’espace caractéristique afin d’améliorer la précision de classification du classificateur EK-NN. Basées sur ces deux études théoriques, un système robuste de prédiction est proposé, dans lequel le problème d’apprentissage pour des données de petite taille et déséquilibrées est traité de manière efficace. Pour segmenter automatiquement les tumeurs en TEP, une méthode 3-D non supervisée basée sur le regroupement évidentiel (evidential clustering) et l’information spatiale est proposée. Cette méthode de segmentation mono-modalité est ensuite étendue à la co-segmentation dans des images TEP-TDM, en considérant que ces deux modalités distinctes contiennent des informations complémentaires pour améliorer la précision. Toutes les méthodes proposées ont été testées sur des données cliniques, montrant leurs meilleures performances par rapport aux méthodes de l’état de l’artRadiation therapy is one of the most principal options used in the treatment of malignant tumors. To enhance its effectiveness, two critical issues should be carefully dealt with, i.e., reliably predicting therapy outcomes to adapt undergoing treatment planning for individual patients, and accurately segmenting tumor volumes to maximize radiation delivery in tumor tissues while minimize side effects in adjacent organs at risk. Positron emission tomography with radioactive tracer fluorine-18 fluorodeoxyglucose (FDG-PET) can noninvasively provide significant information of the functional activities of tumor cells. In this thesis, the goal of our study consists of two parts: 1) to propose reliable therapy outcome prediction system using primarily features extracted from FDG-PET images; 2) to propose automatic and accurate algorithms for tumor segmentation in PET and PET-CT images. The theory of belief functions is adopted in our study to model and reason with uncertain and imprecise knowledge quantified from noisy and blurring PET images. In the framework of belief functions, a sparse feature selection method and a low-rank metric learning method are proposed to improve the classification accuracy of the evidential K-nearest neighbor classifier learnt by high-dimensional data that contain unreliable features. Based on the above two theoretical studies, a robust prediction system is then proposed, in which the small-sized and imbalanced nature of clinical data is effectively tackled. To automatically delineate tumors in PET images, an unsupervised 3-D segmentation based on evidential clustering using the theory of belief functions and spatial information is proposed. This mono-modality segmentation method is then extended to co-segment tumor in PET-CT images, considering that these two distinct modalities contain complementary information to further improve the accuracy. All proposed methods have been performed on clinical data, giving better results comparing to the state of the art ones
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Lamprou, Efthymios. "Development and Performance Evaluation of High Resolution TOF-PET Detectors Suitable for Novel PET Scanners." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/162991.
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[ES] La Tomografía por Emisión de Positrones (PET) es una de las técnicas más importantes en la medicina de diagnóstico actual y la más representativa en el campo de la Imagen Molecular. Esta modalidad de imagen es capaz de producir información funcional única, que permite la visualización en detalle, cuantificación y conocimiento de una variedad de enfermedades y patologías. Áreas como la oncología, neurología o la cardiología, entre otras, se han beneficiado en gran medida de esta técnica. A pesar de que un elevado número de avances han ocurrido durante el desarrollo del PET, existen otros que son de gran interés para futuras investigaciones. Uno de los principales pilares actualmente en PET, tanto en investigación como en desarrollo, es la obtención de la información del tiempo de vuelo (TOF) de los rayos gamma detectados. Cuando esto ocurre, aumenta la sensibilidad efectiva del PET, mejorando la calidad señal-ruido de las imágenes. Sin embargo, la obtención precisa de la marca temporal de los rayos gamma es un reto que requiere, además de técnicas y métodos específicos, compromisos entre coste y rendimiento. Una de las características que siempre se ve afectada es la resolución espacial. Como discutiremos, la resolución espacial está directamente relacionada con el tipo de centellador y, por lo tanto, con el coste del sistema y su complejidad.
En esta tesis, motivada por los conocidos beneficios en imagen clínica de una medida precisa del tiempo y de la posición de los rayos gamma, proponemos configuraciones de detectores TOF- PET novedosos capaces de proveer de ambas características. Sugerimos el uso de lo que se conoce como métodos de "light-sharing", tanto basado en cristales monolíticos como pixelados de tamaño diferente al del fotosensor. Estas propuestas hacen que la resolución espacial sea muy alta. Sin embargo, sus capacidades temporales han sido muy poco abordadas hasta ahora. En esta tesis, a través de varios artículos revisados, pretendemos mostrar los retos encontrados en esta dirección, proponer determinadas configuraciones y, además, indagar en los límites temporales de éstas.
Hemos puesto un gran énfasis en estudiar y analizar las distribuciones de la luz centellante, así como su impacto en la determinación temporal. Hasta nuestro conocimiento, este es el primer trabajo en el que se estudia la relación de la determinación temporal y la distribución de luz de centelleo, en particular usando SiPM analógicos y ASICs. Esperamos que esta tesis motive y permita otros muchos trabajos orientados en nuevos diseños, útiles para instrumentación PET, así como referencia para otros trabajos.
Esta tesis esta organizada como se describe a continuación. Hay una introducción compuesta por tres capítulos donde se resumen los conocimientos sobre imagen PET, y especialmente aquellos relacionados con la técnica TOF-PET. Algunos trabajos recientes, pero aún no publicados se muestran también, con el objetivo de corroborar ciertas ideas. En la segunda parte se incluyen las cuatro contribuciones que el candidato sugiere para el compendio de artículos.[CA] La Tomografia per Emissió de Positrons (PET) és una de les tècniques més importants en la medicina de diagnòstic actual i la més representativa en el camp de la Imatge Molecular. Esta modalitat d'imatge és capaç de produir informació funcional única, que permet la visualització en detall, quantificació i coneixement d'una varietat de malalties i patologies. Àrees com l'oncologia, neurologia o la cardiologia, entre altres, s'han beneficiat en gran manera d'aquesta tècnica. Tot i que un elevat nombre d'avanços han ocorregut durant el desenvolupament del PET, hi ha altres que són de gran interés per a futures investigacions. Un dels principals pilars actuals en PET, tant en investigació com en desenvolupament, és l'obtenció de la informació del temps de vol (TOF en anglès) dels raigs gamma detectats. Quan açò ocorre, augmenta la sensibilitat efectiva del PET, millorant la qualitat senyal-soroll de les imatges. No obstant això, l'obtenció precisa de la marca temporal dels raigs gamma és un repte que requerix, a més de tècniques i mètodes específics, compromisos entre cost i rendiment. Una de les característiques que sempre es veu afectada és la resolució espacial. Com discutirem, la resolució espacial està directament relacionada amb el tipus de centellador, i per tant, amb el cost del sistema i la seua complexitat. En aquesta tesi, motivada pels coneguts beneficis en imatge clínica d'una mesura precisa del temps i de la posició dels raigs gamma, proposem nouves configuracions de detectors TOF-PET capaços de proveir d'ambduess característiques. Suggerim l'ús del que es coneix com a mètodes de "light-sharing", tant basat en cristalls monolítics com pixelats de diferent tamany del fotosensor. Aquestes propostes fan que la resolució espacial siga molt alta. No obstant això, les seues capacitats temporals han sigut molt poc abordades fins ara. En aquesta tesi, a través de diversos articles revisats, pretenem mostrar els reptes trobats en aquesta direcció, proposar determinades configuracions i, a més, indagar en els límits temporals d'aquestes. Hem posat un gran èmfasi a estudiar i analitzar les distribucions de la llum centellejant, així com el seu impacte en la determinació temporal. Fins al nostre coneixement, aquest és el primer treball en què s'estudia la relació de la determinació temporal i la distribució de llum de centelleig, en particular utilitzant SiPM analògics i ASICs. Esperem que aquesta tesi motive i permeta molts altres treballs orientats en nous dissenys, útils per a instrumentació PET, així com referència per a altres treballs. Aquesta tesi esta organitzada com es descriu a continuació. Hi ha una introducció composta per tres capítols on es resumeixen els coneixements sobre imatge PET i, especialmente, aquells relacionats amb la tècnica TOF-PET. Alguns treballs recents, però encara no publicats es mostren també, amb l'objectiu de corroborar certes idees. La segona part de la tesi conté els quatre articles revisats que el candidat suggereix.
[EN] Positron Emission Tomography (PET) is one of the greatest tools of modern diagnostic medicine and the most representative in the field of molecular imaging. This imaging modality, is capable of providing a unique type of functional information which permits a deep visualization, quantification and understanding of a variety of diseases and pathologies. Areas like oncology, neurology, or cardiology, among others, have been well benefited by this technique. Although numerous important advances have already been achieved in PET, some other individual aspects still seem to have a great potential for further investigation. One of the main trends in modern PET research and development, is based in the extrapolation of the Time- Of-Flight (TOF) information from the gamma-ray detectors. In such case, an increase in the effective sensitivity of PET is accomplished, resulting in an improved image signal-to-noise ratio. However, the direction towards a precise decoding of the photons time arrival is a challenging task that requires, besides specific approaches and techniques, tradeoffs between cost and performance. A performance characteristic very habitually compromised in TOF-PET detector configurations is the spatial resolution. As it will be discussed, this feature is directly related to the scintillation materials and types, and consequently, with system cost and complexity. In this thesis, motivated by the well-known benefits in clinical imaging of a precise time and spatial resolution, we propose novel TOF-PET detector configurations capable of inferring both characteristics. Our suggestions are based in light sharing approaches, either using monolithic detectors or crystal arrays with different pixel-to-photosensor sizes. These approaches, make it possible to reach a precise impact position determination. However, their TOF capabilities have not yet been explored in depth. In the present thesis, through a series of peer-reviewed publications we attempt to demonstrate the challenges encountered in these kinds of configurations, propose specific approaches improving their performance and eventually reveal their limits in terms of timing. High emphasis is given in analyzing and studying the scintillation light distributions and their impact to the timing determination. To the best of our knowledge, this is one of the first works in which such detailed study of the relation between light distribution and timing capabilities is carried out, especially when using analog SiPMs and ASICs. Hopefully, this thesis will motivate and enable many other novel design concepts, useful in PET instrumentation as well as it will serve as a helpful reference for similar attempts. The present PhD thesis is organized as follows. There is an introduction part composed by three detailed sections. We attempt to summarize here some of the knowledge related to PET imaging and especially with the technique of TOF-PET. Some very recent but still unpublished results are also presented and included in this part, aiming to support statements and theories. The second part of this thesis lists the four peer-reviewed papers that the candidate is including.
This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 695536). It has also been supported by the Spanish Ministerio de Economía, Industria y Competitividad under Grants No. FIS2014-62341-EXP and TEC2016-79884-C2-1-R. Efthymios Lamprou has also been supported by Generalitat Valenciana under grant agreement GRISOLIAP-2018-026.
Lamprou, E. (2021). Development and Performance Evaluation of High Resolution TOF-PET Detectors Suitable for Novel PET Scanners [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/162991
TESIS
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Benoit, Didier. "Conception, reconstruction et évaluation d'une géométrie de collimation multi-focale en tomographie d'émission monophotonique préclinique." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00949951.
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La tomographie d'émission monophotonique (TEMP) dédiée au petit animal est une technique d'imagerie nucléaire qui joue un rôle important en imagerie moléculaire. Les systèmes TEMP, à l'aide de collimateurs pinholes ou multi-pinholes, peuvent atteindre des résolutions spatiales submillimétriques et une haute sensibilité pour un petit champ de vue, ce qui est particulièrement attractif pour imager des souris. Une géométrie de collimation originale a été proposée, dans le cadre d'un projet, appelé SIGAHRS, piloté par la société Biospace. Ce collimateur présente des longueurs focales qui varient spatialement dans le plan transaxial et qui sont fixes dans le plan axial. Une haute résolution spatiale est recherchée au centre du champ de vue, avec un grand champ de vue et une haute sensibilité. Grâce aux simulations Monte Carlo, dont nous pouvons maîtriser tous les paramètres, nous avons étudié cette collimation originale que nous avons positionnée par rapport à un collimateur parallèle et un collimateur monofocal convergent. Afin de générer des données efficacement, nous avons développé un module multi-CPU/GPU qui utilise une technique de lancer de rayons dans le collimateur et qui nous a permis de gagner un facteur ~ 60 en temps de calcul, tout en conservant ~ 90 % du signal, pour l'isotope ⁹⁹^mTc (émettant à 140,5 keV), comparé à une simulation Monte Carlo classique. Cependant, cette approche néglige la pénétration septale et la diffusion dans le collimateur. Les données simulées ont ensuite été reconstruites avec l'algorithme OSEM. Nous avons développé quatre méthodes de projection (une projection simple (S-RT), une projection avec volume d'intersection (S-RT-IV), une projection avec calcul de l'angle solide (S-RT-SA) et une projection tenant compte de la profondeur d'interaction (S-RT-SA-D)). Nous avons aussi modélisé une PSF dans l'espace image, anisotrope et non-stationnaire, en nous inspirant de la littérature existante. Nous avons étudié le conditionnement de la matrice système pour chaque projecteur et collimateur, et nous avons comparé les images reconstruites pour chacun des collimateurs et pour chacun des projecteurs. Nous avons montré que le collimateur original proposé est le système le moins bien conditionné. Nous avons aussi montré que la modélisation de la PSF dans l'image ainsi que de la profondeur d'intéraction améliorent la qualité des images reconstruites ainsi que le recouvrement de contraste. Cependant, ces méthodes introduisent des artefacts de bord. Comparé aux systèmes existants, nous montrons que ce nouveau collimateur a un grand champ de vue (~ 70 mm dans le plan transaxial), avec une résolution de 1,0 mm dans le meilleur des cas, mais qu'il a une sensibilité relativement faible (1,32x10⁻² %).
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Monteiro, André Miguel Martins Costa Correia. "GATE Model of a SPECT-CT equipment for breast cancer diagnosis." Master's thesis, 2016. http://hdl.handle.net/10451/26323.
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Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Radiações em Diagnóstico e Terapia)Universidade de Lisboa, Faculdade de Ciências, 2016Dedicated imaging systems for breast cancer imaging have been comprehensively studied over the past decade. However, since they comprise only one imaging modality these systems are only able to provide either anatomical or functional information of the object of interest. The aim of this work was to simulate and evaluate the implementation of a dedicated system that would be able to extract information regarding both systems in order to provide a complementary diagnostic tool which could be used in inconclusive diagnosis cases. The proposed solution was to develop two dedicated systems. A dedicated breast computed tomography (DBCT) system that would provide anatomical information and a dedicated single photon emission mammography (SPEM), using convergent collimators, that would retrieve functional information. To create a computer model of this multimodality system, Monte Carlo (MC) simulations were conducted with Geant4 Application for Emission Tomography (GATE) using a simple breast cylindrical phantom with 35 mm radius and 150 mm height, which had 5 mm radius spherical masses composed of aluminum inside it. For DBCT, the MC simulations were acquired with a PaxScan A® 2520D/CL Amorphous Silicon Digital X-Ray Imager with total dimensions of 192x242x4 mm and 0.508x0.508x4 mm pixels, over 16 projections covering 180º of the phantom, extended to 360º exploiting its cylindrical symmetry. Inside the phantom were placed 5 tumour masses equidistantly along two axis with a tumour mass at the center. For SPECT, the MC simulations were performed using a dual-head SPECT scanner designed by Dr. Ricardo Capote with 64.0x151.2x188.5 mm as dimensions with pixelated LYSO crystals of 20x2x2 mm and convergent collimators with the same phantom, but with the same 5 mm radius tumour masses placed solely in the x axis. The MC simulations were conducted in a computer cluster with 4 executions machines. The projections resultant of the simulations were reconstructed using different algorithms. For DBCT it was used an analytical method of filtered backprojection (FBP) and for SPEM it was used an iterative maximum likelihood expectation maximization (MLEM) algorithm. To validate the results two non-absolut metrics were calculated to make a relative evaluation of the image quality results. These metrics were only applied to DBCT, since the results obtained for SPEM were not as expected. Contrast and contrast to noise ratio demonstrated that the image quality degrades from the center to the periphery of the DBCT detector. In conclusion, the acquired results demonstrated the feasibility of breast dedicated systems to, especially for the DBCT system, which yielded the best results, but further development need to be pursued in order to take the most potential of the developed systems which have potential for being used in future studies with more complex and realistic conditions and voxelised phantoms.
O cancro da mama é o tipo de cancro mais diagnosticado nas mulheres, precedido apenas em termos de incidência estatística pelo cancro da pele. No que diz respeito ao número de mortes, o cancro da mama encontra-se também entre os mais importantes relativamente às mulheres, sendo secundado apenas pelo cancro do pulmão em mortalidade. A deteção precoce de neoplasias na mama ganha assim um papel fundamental de forma a garantir o sucesso do tratamento, melhorando as taxas de sobrevivência daqueles aos quais são diagnosticadas neoplasias mamárias. É nessa deteção que a imagiologia médica se apresenta atualmente como essencial. Não apenas no tremendo esforço nas últimas décadas por melhorar as modalidades imagiológicas já implementadas clinicamente, mas também pelo desenvolvimento de novas que possam adicionar nova informação relevante, especialmente quando perante casos em que o exame médico utilizado não é conclusivo. Atualmente, a mamografia por raios X é a técnica imagiológica utilizada em prática clínica corrente em rastreios de cancro da mama, rastreios esses que permitem um diagnóstico mais precoce, tendo contribuído nas últimas décadas para um aumento muito significativo das taxas de sobrevivência. No entanto, esta técnica apresenta diversas limitações que podem condicionar o correto diagnóstico dos doentes. Sendo uma técnica que fornece essencialmente informação anatómica e a duas dimensões, apesar de esta oferecer um elevado nível de sensibilidade, a sua especificidade é menor. Isto pode levar a uma menor capacidade de discernir entre lesão benigna e maligna, resultado principalmente da não incorporação de informação metabólica relativa às massas tumorais, bem como, da possibilidade da não identificação de neoplasias, resultado da sobreposição de planos sempre inerente a uma técnica imagiológica apenas a duas dimensões. Desta forma, torna-se necessário recorrer a outras técnicas que providenciem informação adicional sobre as neoplasias detetadas, mas também que possibilitem a visualização a três dimensões, evitando ao máximo procedimentos invasivos desnecessários, tais como biopsias. Sistemas dedicados para examinar a mama, tirando partido da cada vez maior miniaturização dos componentes eletrónicos essenciais para o desenvolvimento de novos detetores, que possibilitem a aquisição a três dimensões, com uma menor dose de radiação ionizante, surgem com grande expressão em todo o trabalho de investigação realizado no desenvolvimento na área da imagiologia médica. Este incide não só no sentido de restringir ao máximo a zona sobre a qual incide a radiação, mas também no sentido de dar novas ferramentas de diagnóstico para casos onde este é mais difícil, sobretudo quando relativo a mamas de maior densidade. Nesse sentido, e como forma de obter informação complementar, a tomografia computorizada (TC) por raios X – que fornece informação anatómica tridimensional – e a tomografia computorizada por emissão de fotão único (TCEFU), que ao ser aplicada em específico ao exame da mama toma o nome de mamografia por emissão de fotão único (MEFU) – que providencia informação funcional tridimensional – são duas modalidades que podem ser utilizadas em sistemas dedicados, como forma de meio de diagnóstico complementar, combatendo assim as limitações inerentes à mamografia. Nesta dissertaçãio, é apresentada uma solução que, por meio da incorporação de dois sistemas dedicados das modalidades acima mencionadas, tem como objetivo a implementação através de simulações de Monte Carlo (MC), com recurso ao programa Geant4 Application for Emission Tomography (GATE) que possui a sua própria linguagem macro dedicada para desenvolvimento de simulações de MC. Este programa, pela incorporação de outros programas externos a si (CLHEP, ROOT, for GEometry ANd Tracking (Geant4)), permite projetar simulações complexas, combinando a vantagem da utilização do Geant4 - com os seus processos físicos bem validados e geometria sofisticada - com funcionalidades próprias para tomografia de emissão. Uma vez que o GATE utiliza uma linguagem própria, a necessidade de uma programação de outra forma exaustiva em C++ é eliminada, necessidade essa que seria uma realidade caso fosse usado o Geant4 diretamente. Utilizando um fantoma cilíndrico com 35 mm de raio e 150 mm de altura, com composição semelhante a tecido mamário, foram realizadas simulações para ambas as modalidades, onde foram colocadas massas tumorais compostas por alumínio, ao longo de várias posições no mesmo eixo, de forma a avaliar a qualidade da imagem conseguida através da aquisição por parte destes equipamentos. A simulação de TC foi efetuada colocando no interior do fantoma 5 massas tumorais com 5 mm de raio equidistantes entre si ao longo do eixo do 𝑥 e do 𝑧, resultando numa disposição em L. A aquisição foi adquirida em 16 projeções de 10 s a 180o do cilindro, totalizando um tempo total de 160 s. De forma a englobar 360o em torno do fantoma as projeções obtidas foram posteriormente espelhadas e incorporados no resultado final, aproveitando a simetria simétrica do mesmo. A disposição em L permitiu assim verificar a qualidade da imagem reconstruída relativamente a dois tipos de distância em relação ao centro do detetor de 192x242x4 mm, compostos por pixéis quadrangulares de dimensões 0.508x0.508x4 mm. Para o MEFU foi utilizado o detetor desenvolvido pelo Dr. Ricardo Capote, utilizando os mesmos parâmetros de aquisição utilizados no trabalho desenvolvido pelo Dr. Ricardo Capote, composto por duas câmaras gama de 64x151.2x188.5 mm, constituídos por cristais pixelizados de LYSO, sendo que cada um tinha 20x2x2 mm. De forma a direcionar a radiação gama a detetar estas câmaras utilizavam também colimadores convergentes. Tal como no trabalho do Dr. Ricardo Capote foram feitas simulações com 64 projeções por câmara ao longo de uma órbita circular, totalizando 10 minutos de duração de exame. No entanto, ao contrário do que aconteceu para a modalidade de TC, apenas se realizaram simulações onde foram inseridas no interior massas tumorais que variavam a sua posição relativa, apenas em uma coordenada. Os ficheiros finais da TC foram posteriormente processados com recurso a um ficheiro de C++, utilizando comandos próprios do programa ROOT, de forma a extrair as projeções da imagem, sendo posteriormente feita a sua reconstrução tridimensional utilizando o algoritmo analítico Filtered BackProjection (FBP), implementado no MATLAB®. De forma similar, os resultados da MEFU foram tratados por um ficheiro .C que extraía as contagens nos detetores a partir do ficheiro resultado das simulações, sendo estes posteriormente reconstruídos tridimensionalmente com recurso ao algoritmo iterativo Maximum Likelihood Expectation Maximization (MLEM). Após ser feita a reconstrução de ambas as modalidades, os resultados foram validados por meio da utilização de métricas não-absolutas relativas apenas para a TC, nomeadamente o contraste e o rácio entre o contraste e o ruído. Os resultados obtidos demonstraram uma degradação da imagem do centro do detetor para a periferia, degradação essa que seria o expectável tendo em conta a geometria de toda a simulação. Desta forma, foram implementados ambos sistemas com a visualização de um fantoma cilíndrico simples. As métricas utilizadas para avaliação na TC comprovaram a sua viabilidade. No entanto, o desenvolvimento destes sistemas, teve como principal objetivo permitir a possibilidade de ser realizada uma futura implementação que incorporasse as duas modalidades, dando assim dois tipos de informação complementares no mesmo exame. De modo a que o modelo pudesse ser utilizado em ocasiões futuras, e até como ponto de referência para a utilização do próprio GATE em qualquer projeto, a metodologia empregue foi descrita exaustivamente. Espera-se que o modelo elaborado no decorrer deste trabalho, apesar dos resultados de MEFU não terem sido os melhores, possa servir como ponto de partida para novos estudos. Estudos futuros poderão incorporar algoritmos mais complexos de reconstrução, ou ainda efetuar a adaptação das simulações de MC para utilização computação em GPU, utilizando fantomas voxelizados, podendo assim diminuir drasticamente o tempo de computação das simulações.
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Agasthya, Greeshma Ananth. "Low-dose imaging of liver diseases through neutron stimulated emission computed tomography: Simulations in GEANT4." Diss., 2013. http://hdl.handle.net/10161/7121.
Full textAbstract:
Neutron stimulated emission computed tomography (NSECT) is a non-invasive, tomographic imaging technique with the ability to locate and quantify elemental concentration in a tissue sample. Previous studies have shown that NSECT has the ability to differentiate between benign and malignant tissue and diagnose liver iron overload while using a neutron beam tomographic acquisition protocol followed by iterative image reconstruction. These studies have shown that moderate concentrations of iron can be detected in the liver with moderate dose levels and long scan times. However, a low-dose, reduced scan time technique to differentiate various liver diseases has not been tested. As with other imaging modalities, the performance of NSECT in detecting different diseases while reducing dose and scan time will depend on the acquisition techniques and parameters that are used to scan the patients. In order to optimize a clinical liver imaging system based on NSECT, it is important to implement low-dose techniques and evaluate their feasibility, sensitivity, specificity and accuracy by analyzing the generated liver images from a patient population. This research work proposes to use Monte-Carlo simulations to optimize a clinical NSECT system for detection, localization, quantification and classification of liver diseases. This project has been divided into three parts; (a) implement two novel acquisition techniques for dose reduction, (b) modify MLEM iterative image reconstruction algorithm to incorporate the new acquisition techniques and (c) evaluate the performance of this combined technique on a simulated patient population.
The two dose-reduction, acquisition techniques that have been implemented are; (i) use of a single angle scanning, multi-detector acquisition system and (ii) the neutron-time resolved imaging (n-TRI) technique. In n-TRI, the NSECT signal has been resolved in time by a function of the speed of the incident neutron beam and this information has been used to locate the liver lesions in the tissue. These changes in the acquisition system have been incorporated and used to modify MLEM iterative image reconstruction algorithm to generate liver images. The liver images are generated from sinograms acquired by the simulated n-TRI based NSECT scanner from a simulated patient population.
The simulated patient population has patients of different sizes, with different liver diseases, multiple lesions with different sizes and locations in the liver. The NSECT images generated from this population have been used to validate the liver imaging system developed in this project. Statistical tests such as ROC and student t-tests have been used to evaluate this system. The overall improvement in dose and scan time as compared to the NSECT tomographic system have been calculated to verify the improvement in the imaging system. The patient dose was calculated by measuring the energy deposited by the neutron beam in the liver and surrounding body tissue. The scan time was calculated by measuring the time required by a neutron source to produce the neutron fluence required to generate a clinically viable NSECT image.
Simulation studies indicate that this NSECT system can detect, locate, quantify and classify liver lesions in different sized patients. The n-TRI imaging technique can detect lesions with wet iron concentration of 0.5 mg/g or higher in liver tissue in patients with 30 cm torso and can quantify lesions at 0.3 ns timing resolution with errors ≤ 17.8%. The NSECT system can localize and classify liver lesions of hemochromatosis, hepatocellular carcinoma, fatty liver tissue and cirrhotic liver tissue based on bulk and trace element concentrations. In a small patient with a torso major axis of 30 cm, the n-TRI based liver imaging technique can localize 91.67% of all lesions and classify lesions with an accuracy of 88.23%. The dose to the small patient is 0.37 mSv a reduction of 39.9% as compared to the NSECT tomographic system and scan times are comparable to that of an abdominal MRI scan. In a bigger patient with a torso major axis of 50cm, the n-TRI based technique can detect 75% of the lesions, while localizing 66.67% of the lesions, the accuracy of classification is 76.47%. The effective dose equivalent delivered to the larger patient is 1.57 mSv for a 68.8% decrease in dose as compared to a tomographic NSECT system.
The research performed for this dissertation has two important outcomes. First, it demonstrates that NSECT has the clinical potential for detection, localization and classification of liver diseases in patients. Second, it provides a validation of the simulation of a novel low-dose liver imaging technique which can be used to guide future development and experimental implementation of the technique.
Dissertation
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Kapadia, Anuj. "Accuracy and Patient Dose in Neutron Stimulated Emission Computed Tomography for Diagnosis of Liver Iron Overload: Simulations in GEANT4." Diss., 2007. http://hdl.handle.net/10161/380.
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Neutron stimulated emission computed tomography (NSECT) is being proposed as an experimental technique to diagnose iron overload in patients. Proof-of-concept experiments have suggested that NSECT may have potential to make a non-invasive diagnosis of iron overload in a clinical system. The technique's sensitivity to high concentrations of iron combined with tomographic acquisition ability gives it a unique advantage over other competing modalities. While early experiments have demonstrated the efficacy of detecting samples with high concentrations of iron, a tomography application for patient diagnosis has never been tested. As with any other tomography system, the performance of NSECT will depend greatly on the acquisition parameters that are used to scan the patient. In order to determine the best acquisition geometry for a clinical system, it is important to evaluate and understand the effects of varying each individual acquisition parameter on the accuracy of the reconstructed image. This research work proposes to use Monte-Carlo simulations to optimize a clinical NSECT system for iron overload diagnosis.Simulations of two NSECT systems have been designed in GEANT4, a spectroscopy system to detect uniform concentrations of iron in the liver, and a tomography system to detect non-uniform iron overload. Each system has been used to scan simulated samples of both disease models in humans to determine the best scanning strategy for each. The optimal scanning strategy is defined as the combination of parameters that provides maximum accuracy with minimum radiation dose. Evaluation of accuracy is performed through ROC analysis of the reconstructed spectrums and images. For the spectroscopy system, the optimal acquisition geometry is defined in terms of the number of neutrons required to detect a clinically relevant concentration of iron. For the tomography system, the optimal scanning strategy is defined in terms of the number of neutrons and the number of spatial and angular translation steps used during acquisition. Patient dose for each simulated system is calculated by measuring the energy deposited by the neutron beam in the liver and surrounding body tissue. Simulation results indicate that both scanning systems can detect wet iron concentrations of 5 mg/g or higher. Spectroscopic scanning with sufficient accuracy is possible with 1 million neutrons per scan, corresponding to a patient dose of 0.02 mSv. Tomographic scanning requires 8 angles that sample the image matrix at 1 cm projection intervals with 4 million neutrons per projection, which corresponds to a total body dose of 0.56 mSv. The research performed for this dissertation has two important outcomes. First, it demonstrates that NSECT has the clinical potential for iron overload diagnosis in patients. Second, it provides a validated simulation of the NSECT system which can be used to guide future development and experimental implementation of the technique.Dissertation
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Kapadia, Anuj Jawahar. "Accuracy and Patient Dose in Neutron Stimulated Emission Computed Tomography for Diagnosis of Liver Iron Overload Simulations in GEANT4." Diss., 2007. http://hdl.handle.net/10161/380.
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"Application of Joint Intensity Algorithms to the Registration of Emission Tomography and Anatomical Images." University of Technology, Sydney. Department of Applied Physics, 2004. http://hdl.handle.net/2100/288.
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In current practice, it is common in medical diagnosis or treatment monitoring for a patient to require multiple examinations using different imaging techniques. Magnetic resonance (MR) imaging and computed tomography (CT) are good at providing anatomical information. Three-dimensional functional information about tissues and organs is often obtained with radionuclide imaging modalities: positron emission tomography (PET) and single photon emission tomography (SPET). In nuclear medicine, such techniques must contend with poor spatial resolution, poor counting statistics of functional images and the lack of correspondence between the distribution of the radioactive tracer and anatomical boundaries. Information gained from anatomical and functional images is usually of a complementary nature. Since the patient cannot be relied on to assume exactly the same pose at different times and possibly in different scanners, spatial alignment of images is needed. In this thesis, a general framework for image registration is presented, in which the optimum alignment corresponds to a maximum of a similarity measure. Particular attention is drawn to entropy-based measures, and variance-based measures. These similarity measures include mutual information, normalized mutual information and correlation ratio which are the ones being considered in this study. In multimodality image registration between functional and anatomical images, these measures manifest superior performance compared to feature-based measures. A common characteristic of these measures is the use of the joint-intensity histogram, which is needed to estimate the joint probability and the marginal probability of the images. A novel similarity measure is proposed, the symmetric correlation ratio (SCR), which is a simple extension of the correlation ratio measure. Experiments were performed to study questions pertaining to the optimization of the registration process. For example, do these measures produce similar registration accuracy in the non-brain region as in the brain? Does the performance of SPET-CT registration depend on the choice of the reconstruction method (FBP or OSEM)? The joint-intensity based similarity measures were examined and compared using clinical data with real distortions and digital phantoms with synthetic distortions. In automatic SPET-MR rigid-body registration applied to clinical brain data, a global mean accuracy of 3.9 mm was measured using external fiducial markers. SCR performed better than mutual information when sparse sampling was used to speed up the registration process. Using the Zubal phantom of the thoracic-abdominal region, SPET projections for Methylenediphosponate (MDP) and Gallium-67 (67Ga) studies were simulated for 360 degree data, accounting for noise, attenuation and depth-dependent resolution. Projection data were reconstructed using conventional filtered back projection (FBP) and accelerated maximum likelihood reconstruction based on the use of ordered subsets (OSEM). The results of SPET-CT rigid-body registration of the thoracic-abdominal region revealed that registration accuracy was insensitive to image noise, irrespective of which reconstruction method was used. The registration accuracy, to some extent, depended on which algorithm (OSEM or FBP) was used for SPET reconstruction. It was found that, for roughly noise-equivalent images, OSEM-reconstructed SPET produced better registration than FBP-reconstructed SPET when attenuation compensation (AC) was included but this was less obvious for SPET without AC. The results suggest that OSEM is the preferable SPET reconstruction algorithm, producing more accurate rigidbody image registration when AC is used to remove artifacts due to non-uniform attenuation in the thoracic region. Registration performance deteriorated with decreasing planar projection count. The presence of the body boundary in the SPET image and matching fields of view were shown not to affect the registration performance substantially but pre-processing steps such as CT intensity windowing did improve registration accuracy. Non-rigid registration based on SCR was also investigated. The proposed algorithm for non-rigid registration is based on overlapping image blocks defined on a 3D grid pattern and a multi-level strategy. The transformation vector field, representing image deformation is found by translating each block so as to maximize the local similarity measure. The resulting sparsely sampled vector field is interpolated using a Gaussian function to ensure a locally smooth transformation. Comparisons were performed to test the effectiveness of SCR, MI and NMI in 3D intra- and inter-modality registration. The accuracy of the technique was evaluated on digital phantoms and on patient data. SCR demonstrated a better non-rigid registration than MI when sparse sampling was used for image block matching. For the high-resolution MR-MR image of brain region, the proposed algorithm was successful, placing 92% of image voxels within less than or equal to 2 voxels of the true position. Where one of the images had low resolution (e.g. in CT-SPET, MR-SPET registration), the accuracy and robustness deteriorated profoundly. In the current implementation, a 3D registration process takes about 10 minutes to complete on a stand alone Pentium IV PC with 1.7 GHz CPU and 256 Mbytes random access memory on board.
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Ma, Kuo-Hsing, and 馬國興. "Application and evaluation of dual-isotope single photon emission tomography in non-human primates." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/01243234491396911211.
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博士國防醫學院
生命科學研究所
91
Parkinson's disease (PD) is a degeneration of the nigrostriatal dopaminergic pathway, leading to a selective loss of dopamine in the striatum (ST). In addition to decline of dopamine, serotonergic neurons are affected by the disease process. [99mTc]TRODAT and [123I]IBZM are two imaging radioligands, respectively specific for pre- and post-synaptic dopamine binding sites. Using single-photon emission computed tomography (SPECT), [99mTc]TRODAT can demonstrate the status of dopaminergic neurons in vivo, whereas [123I]IBZM reflect the density of dopamine D2 receptor. These two radioligands can differentiate patients with Parkinson’s disease from healthy individuals based on co-evaluated differences in uptake on brain SPECT. [123I]ADAM is an imaging agent of serotonin transporters (SERT), with potential application for the study of neuropsychiatry diseases such as depression, drug addiction, suicide, anxiety, and eating disorders. Here we underwent three studies using [99mTc]TRODAT/SPECT , [123I]IBZM/SPECT, and [123I]ADAM/SPECT in Formosan rock monkeys to test the following hypotheses:1)There was a positive correlation between specific uptake ratio (SUR) measures obtained for [99mTc]TRODAT/SPECT and 6-[18F]fluoro-dopa in monkeys. 2) Dual SPECT imaging using [99mTc]TRODAT and [123I]IBZM could differentiate normal monkeys from a bilateral 6-OHDA-lesioned monkey 3) brain serotonin transporters could decrease after a bilateral 6-OHDA lesion on the nigra-striatal pathway. The first study was to compare [99mTc]TRODAT/SPECT with 6-[18F]fluoro-dopa/PET in the evaluation of PD using a primate model. Three monkeys including one bilateral 6-OHDA-lesioned monkey (2 years after 6-OHDA treatment) and two controls were examined by both [99mTc]TRODAT/SPECT and 6-[18F]fluoro-dopa/PET. For the PD monkey, expression of parkinsonian behavior and 6-[18F]fluoro-dopa/PET were used to evaluate the severity of the lesion. [99mTc]TRODAT was prepared from a lyophilized kit. After intravenous injection of the radiotracer, SPECT was acquired over 4 h using a dual-head camera equipped with ultra-high resolution fan-beam collimators. Both uptake measurement and visual assessment were performed. Data were compared with motor behavior and PET imaging. The striatal uptake in both healthy and PD monkeys increased continuously during the study, although the gradient of increase was less prominent in the diseased monkey. The increased uptake in the controls appeared becoming blunt around 4 h after injection. A profound decrease of [99mTc] TRODAT uptake was found in the ST of the PD monkey compared with the controls. In the PD monkey, the decrease of ST uptake contralateral to the more affected side of the body was more prominent compared to the ipsilateral side. In addition, greater loss occurred in the contralateral side of the putamen. Changes of uptake ratios in ST and its subnuclei of the PD monkey were significantly correlated with those measured from PET. The loss of ST uptake appeared greater in SPECT than the corresponding PET with both visual and uptake analyses. In conclusion, our data indicate that [99mTc]TRODAT with conventional nuclear medicine camera system may provide a suitable tool in evaluating pakinsonism in a primate model. In second study, we evaluated pre- and post-synaptic binding sites of the dopamine system in three normal and one parkinsonian (2 years after 6-OHDA treatment) monkeys using simultaneous [99mTc]TRODAT and [123I]IBZM imaging. [99mTc]TRODAT and [123I]IBZM were administered almost simultaneously and the SPECT images were acquired over 4 h using a dual-headed gamma camera equipped with ultra-high resolution fan-beam collimators. Data were obtained using energy window of 15% centered on 140 keV for 99mTc in conjunction with 10% asymmetric energy window in a lower bound at 159 keV for 123I. Single SPECT studies of [99mTc]TRODAT and [123I]IBZM were also performed. We found a comparable image quality and uptake ratios between single- and dual-isotope studies. There are higher TRODAT uptakes in the controls monkeys than the 6-OHDA-lesioned monkey. The uptake of [123I] IBZM showed no significant difference between controls and 6-OHDA-lesioned monkey. Our results suggest that dual isotope imaging using [99mTc]TRODAT and [123I]IBZM may be a useful means in evaluating the changes of both pre- and post-synaptic dopamine system in a primate model of parkinsonism. The third study was undertaken to image central SERT using [123I]ADAM/SPECT in healthy and parkinsonian primates. Two healthy and a 6-OHDA induced PD monkey (6 years after 6-OHDA treatment) were studied. SPECT images of each monkey were obtained after [123I]ADAM (180 MBq) injection for 4 h using a dual-headed camera equipped with ultrahigh resolution fan-beam collimators (GE, Millennium VG Hawkeye). Except for visual inspection, SUR of midbrain (MB), thalamus (TH), striatum (ST), and frontal lobe (FL) using cerebellum as reference were measured. The SPECT images showed discernable uptake of [123I]ADAM in the MB, TH, ST, and FL of normal monkeys, whereas cerebellum had little uptake. A comparable SUR of MB was found between normal and PD monkey, but decreased SURs were found in the TH, ST, and FL of PD monkey. The brain distribution of [123I]ADAM in normal monkeys appears correlated with the known distribution of SERT. The decreased SUR of TH, ST, and FL in the PD monkey are consistent with the postmortem study, suggesting that PD might also affect SERT in TH, ST, and FL.
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Hsu, Shih Chieh, and 許詩婕. "Investigation on the preparative requirements of hydroxymethyl fenbufen octyl amide for application in positron emission tomography." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/tq995p.
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Lin, Chang-Shiun, and 林昌勳. "Application of the Intraoperative Dual Photon Emission Computed Tomography System in Sentinel Lymph Node Detection: A Simulation Study." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/55283983834524927141.
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博士國立清華大學
生醫工程與環境科學系
104
The sentinel lymph node (SLN) hypothesis is applied as part of the standard procedure for identifying early-stage breast cancer. Thus, an imaging system that can locate SLNs in operating rooms is desired. Several 2-D probe imaging systems and a freehand single-photon emission-computed tomography (fhSPECT) system have been proposed. However, 2-D probe imaging systems are affected by shine-through and shadowing effects. Here, we proposed an alternative to 3D imaging systems, i.e., a dual-photon emission computed tomography (DuPECT) system, which integrates both preoperative and intraoperative information to locate SLNs using cascade photons emitted isotopes such as Se-75 and In-111. The system consists of a LaBr3-based probe and planar head, a collimation system, and a coincidence circuit. When two photons from each disintegration were detected simultaneously, the slat and parallel-hole collimator define a plane and a line, respectively, which represent the possible flight paths of each photon. SLNs can be located using the line-plane intersection. In this study, Se-75 was used to evaluate the DuPECT concept, performance, and optimization of collimator configurations using Monte Carlo software developed in our laboratory. The result of the performance evaluation indicates that the randoms rate increases with increased initial activities, while the scatter rate is lower than 1.2 count/s for various activities. The sensitivity is 0.23±0.01 cps/MBq, which is significantly lower than that of most 2-D probe imaging systems (6.5–2,200 cps/MBq). In a simulated imaging study, four injection sites and two LNs placed at various depths are minimally distinguishable. However, the LNs are clearly identifiable in the absence of injection sites, indicating that photons emitted from the injection sites seriously deteriorate the image quality. To reduce the influence of injection sites, a pinhole-slat collimation system was proposed. Preliminary results show that the pinhole-slat collimation system succeeds in eliminating photons emitted from injection sites. In addition, a feasibility study of In-111 was conducted with a delay-time-window technique. In-111 was another potential cascade isotope for its appropriategamma energies (171 and 245 keV), short half-life (2.8 days), and relative low dose equivalent. Preliminary result indicates that In-111 is not appropriate for the DuPECT system due to its relative long half-time (85 ns) of the 245 keV gamma-ray. The number of random events increases significantly, leading to failed SLNs identification, as a wide coincidence time window is needed to accommodate the long life-lived 245 keV gamma. The proposed three-dimensional imaging system has the potential to identify injection sites and SLNs. However, difficulties with the low sensitivity for LN detection and in the choice of appropriate radioisotope must be overcome before its clinical usage.
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Chuang, Yen-Chi, and 莊彥騏. "Application of machine learning methodology on the diagnosis of Parkinson''s disease with single photon emission computed tomography." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/gvn95x.
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Lu, Kuan-Pai, and 陸冠百. "Application of A Dual Photons Emission Computed Tomography (DuPECT) System in the Sentinel Lymph Node Location Detection : A Monte Carlo Simulation Study." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/49015349973724801655.
Full textAbstract:
碩士國立清華大學
生醫工程與環境科學系
100
In clinic, the detection of breast metastasis utilizes the aggregating effect of 99mTc labeled pharmaceuticals in sentinel lymph node (SLN). The doctor hold the gamma counting probe to locate the most radioactive (“hottest”) node (i.e. SLN) during operation and perform the resection. But the gamma counting probe technique is susceptible to noise and lack of depth information. In recent years, many groups devoted to develop an imaging probe suitable for the use in the operating room, hoping to overcome the drawbacks of the gamma counting probe. However, traditional single photon emission computed tomography (SPECT) needs to scan 180 degrees to enable the reconstruction of the three dimensional image. As a result, it is impossible to perform real-time imaging for operation purpose. Our laboratory proposes the DuPECT (dual photons emission computed tomography) system employing the radioisotopes that emit two photons simultaneously. The DuPECT system uses the collimator pairs to restrict the direction of incoming photons and the coincidence circuit to determine whether the detected two photons are emitted in the same decay. The source position is simply the intersecting of the trajectory of the detected photons. The DuPECT system provides three-dimensional spatial information without requiring the rotation of the system. Since the biggest limitation of the DuPECT is its low sensitivity, we try to take advantage of the converging collimators (including the fan-beam collimator and cone-beam collimator) to improve the sensitivity. We utilized the GATE Monte-Carlo simulation (MCS) to validate the feasibility of the DuPECT. However, GATE is time-consuming and can’t simulate the geometry with small focal length. So it is essential to develop a more efficient and flexible geometry-based simulation system. In GATE, the interaction between the photons and collimator takes a large portion of the simulation time. Therefore in this study, we design a new Virtual collimator combined with the SimSET to speed up the simulation. The projection data of the Virtual collimator are compared with GATE to validate the accuracy of the proposed system. Both 99mTc and 75Se are used in the slat collimator and the fan-beam collimator simulation. After demonstrating the feasibility of the Virtual collimator, it was used to construct the DuPECT system. In the study, the optimal focal length of the converging collimator was determined first, and then testing the sensitivity and resolution of fan-beam collimator and cone-beam collimator separately to pair with the slat collimator. According to both slat and fan-beam collimator experimental results, we demonstrate that Virtual collimators are in good agreement with GATE simulation in terms of resolution and sensitivity. In Comparison to GATE, the Virtual collimator improve 2~3 and 20~60 times simulating efficiency for slat collimator and fan-beam collimator, respectively. We conclude that the Virtual collimator boost simulating efficiency and produce the accurate results even on complex geometry. The preliminary results suggest the use of Cone-beam collimator for the DuPECT system as it show better resolution and sensitivity than fan-beam collimator. The system sensitivity is 5.42 cps/kBq with resolution of 2.12*2.12*4.38 mm at x, y, and z direction when the source is placed at the focal point. The results demonstrate that the DuPECT system is feasible for intraoperative detection of the SLN. Although the system is strongly position dependent, we believe that the DuPECT-SLN Probe System will come into clinical trial stage in the future.