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Letteratura scientifica selezionata sul tema "Tomographic scanner"

Autore: Grafiati

Pubblicato: 5 aprile 2025

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Articoli di riviste sul tema "Tomographic scanner"

Dao, Viet, Ekaterina Mikhaylova, Max L. Ahnen, Jannis Fischer, Kris Thielemans e Charalampos Tsoumpas. "Evaluation of STIR Library Adapted for PET Scanners with Non-Cylindrical Geometry". Journal of Imaging 8, n. 6 (18 giugno 2022): 172. http://dx.doi.org/10.3390/jimaging8060172.

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Software for Tomographic Image Reconstruction (STIR) is an open source C++ library used to reconstruct single photon emission tomography and positron emission tomography (PET) data. STIR has an experimental scanner geometry modelling feature to accurately model detector placement. In this study, we test and improve this new feature using several types of data: Monte Carlo simulations and measured phantom data acquired from a dedicated brain PET prototype scanner. The results show that the new geometry class applied to non-cylindrical PET scanners improved spatial resolution, uniformity, and image contrast. These are directly observed in the reconstructions of small features in the test quality phantom. Overall, we conclude that the revised “BlocksOnCylindrical” class will be a valuable addition to the next STIR software release with adjustments of existing features (Single Scatter Simulation, forward projection, attenuation corrections) to “BlocksOnCylindrical”.

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Karp, Joel S., Margaret E. Daube-Witherspoon e Gerd Muehllehner. "Factors Affecting Accuracy and Precision in PET Volume Imaging". Journal of Cerebral Blood Flow & Metabolism 11, n. 1_suppl (marzo 1991): A38—A44. http://dx.doi.org/10.1038/jcbfm.1991.35.

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Volume imaging positron emission tomographic (PET) scanners with no septa and a large axial acceptance angle offer several advantages over multiring PET scanners. A volume imaging scanner combines high sensitivity with fine axial sampling and spatial resolution. The fine axial sampling minimizes the partial volume effect, which affects the measured concentration of an object. Even if the size of an object is large compared to the slice spacing in a multiring scanner, significant variation in the concentration is measured as a function of the axial position of the object. With a volume imaging scanner, it is necessary to use a three-dimensional reconstruction algorithm in order to avoid variations in the axial resolution as a function of the distance from the center of the scanner. In addition, good energy resolution is needed in order to use a high energy threshold to reduce the coincident scattered radiation.

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Mangiorou, Eleni. "A Critical Assessment of the Four Basic Methods of Tomographic Imaging". Key Engineering Materials 605 (aprile 2014): 657–60. http://dx.doi.org/10.4028/www.scientific.net/kem.605.657.

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Τhe incidence of and mortality from cancer have been increasing steadily for the past 50 years. Most cancers are not localized when first detected, but early detection is mandatory to improve prognosis. In this article, we performed a comparison of four basic methods of tomographic imaging, Positron emission tomography (PET), the computerized tomography (CT), Magnetic Resonance Imaging (MRI) scanner and the ultrasound scanner (US), in respect to their advantages and disadvantages.

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Michail, Christos, George Karpetas, Nektarios Kalyvas, Ioannis Valais, Ioannis Kandarakis, Kyriakos Agavanakis, George Panayiotakis e George Fountos. "Information Capacity of Positron Emission Tomography Scanners". Crystals 8, n. 12 (9 dicembre 2018): 459. http://dx.doi.org/10.3390/cryst8120459.

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Background: The aim of the present study was to assess the upper information content bound of positron emission tomography (PET) images, by means of the information capacity (IC). Methods: The Geant4 Application for the Tomographic Emission (GATE) Monte Carlo (MC) package was used, and reconstructed images were obtained by using the software for tomographic image reconstruction (STIR). The case study for the assessment of the information content was the General Electric (GE) Discovery-ST PET scanner. A thin-film plane source aluminum (Al) foil, coated with a thin layer of silica and with a 18F-fludeoxyglucose (FDG) bath distribution of 1 MBq was used. The influence of the (a) maximum likelihood estimation-ordered subsets-maximum a posteriori probability-one step late (MLE-OS-MAP-OSL) algorithm, using various subsets (1 to 21) and iterations (1 to 20) and (b) different scintillating crystals on PET scanner’s performance, was examined. The study was focused on the noise equivalent quanta (NEQ) and on the single index IC. Images of configurations by using different crystals were obtained after the commonly used 2-dimensional filtered back projection (FBP2D), 3-dimensional filtered back projection re-projection (FPB3DRP) and the (MLE)-OS-MAP-OSL algorithms. Results: Results shown that the images obtained with one subset and various iterations provided maximum NEQ values, however with a steep drop-off after 0.045 cycles/mm. The single index IC data were maximized for the range of 8–20 iterations and three subsets. The PET scanner configuration incorporating lutetium orthoaluminate perovskite (LuAP) crystals provided the highest NEQ values in 2D FBP for spatial frequencies higher than 0.028 cycles/mm. Bismuth germanium oxide (BGO) shows clear dominance against all other examined crystals across the spatial frequency range, in both 3D FBP and OS-MAP-OSL. The particular PET scanner provided optimum IC values using FBP3DRP and BGO crystals (2.4829 bits/mm2). Conclusions: The upper bound of the image information content of PET scanners can be fully characterized and further improved by investigating the imaging chain components through MC methods.

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Izevbekhai, O. S., P. F. I. Irabor, S. U. Eluehike, B. Oriaifo e O. Otaigbe. "A Tally of Computed Tomographic Scan Findings in the Immediate Post-Installation Period in a Rural Based Hospital in Sub-Saharan Africa". Journal of Advances in Medicine and Medical Research 35, n. 20 (29 agosto 2023): 197–204. http://dx.doi.org/10.9734/jammr/2023/v35i205190.

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Background: The utilization of Computed Tomographic scanners for imaging has gradually evolved in Nigeria since the installation of the first scanner at the University College Hospital, Ibadan in 1989. However, most rural and sub-urban health facilities in Sub-Saharan Africa still lack this all-important modality. Aim and Objectives: To retrospectively determine the pattern of distribution of CT requests, indications and findings on imaging amongst a small cohort of patients scanned in the immediate post-installation phase of a 32-slice Canon CT scanner. Methods: We retrospectively reviewed the requests and reports of thirty patients who had undergone CT examinations of different body regions within the first ten days of installation of a 32-slice Aquilion CT scanner at the Radiology department of one of Nigerias’ leading infectious disease hospital (Irrua Specialist Teaching Hospital) in Irrua town. The data were retrieved, coded and entered into Microsoft excel spreadsheet and further analysed using SPSS version 21. Results: Male patients were more than females in an approximate ratio of 2:1. Majority of patients fell within the age range of 18-64 years. Stroke was the commonest indication and accounted for 33.3% of patients imaged. Although, the craniofacial region was the most commonly imaged region for suspected neurological diseases accounting for 20(67%) of patients, the brain was observed to be grossly normal in 7(23.3%) patients. Rhinosinusitis was the commonest finding seen. Conclusions: Males were the most commonly scanned group, while the craniofacial region was the most imaged region. Neurological disorders and stroke cases together accounted for most CT referrals with stroke being the commonest. Rhinosinusitis and normal brain morphology were the most commonly encountered findings.

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Shampo, Marc A., e Robert A. Kyle. "Allan Cormack—Codeveloper of Computed Tomographic Scanner". Mayo Clinic Proceedings 71, n. 3 (marzo 1996): 288. http://dx.doi.org/10.4065/71.3.288.

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TAGUCHI, Isamu. "Computerized tomographic scanner for iron and steel." Analytical Sciences 1, n. 1 (1985): 93–94. http://dx.doi.org/10.2116/analsci.1.93.

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Jofre, L., M. S. Hawley, A. Broquetas, E. de los Reyes, M. Ferrando e A. R. Elias-Fuste. "Medical imaging with a microwave tomographic scanner". IEEE Transactions on Biomedical Engineering 37, n. 3 (marzo 1990): 303–12. http://dx.doi.org/10.1109/10.52331.

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Abdelkarim, Ayman, Sion K. Roy, April Kinninger, Azadeh Salek, Olivia Baranski, Daniele Andreini, Gianluca Pontone et al. "Evaluation of Image Quality for High Heart Rates for Coronary Computed Tomographic Angiography with Advancement in CT Technology: The CONVERGE Registry". Journal of Cardiovascular Development and Disease 10, n. 9 (19 settembre 2023): 404. http://dx.doi.org/10.3390/jcdd10090404.

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Objective: This study aims to evaluate image quality in patients with heart rates above or equal to 70 beats per minute (bpm), performed on a 16 cm scanner (256-slice General Electric Revolution) in comparison to a CT scanner with only 4 cm of coverage (64 slice Volume CT). Background: Recent advancements in image acquisition, such as whole-heart coverage in a single rotation and post-processing methods in coronary computed tomographic angiography (CCTA), include motion-correction algorithms, such as SnapShot Freeze (SSF), which improve temporal resolution and allow for the assessment of coronary artery disease (CAD) with lower motion scores and better image qualities. Studies from the comprehensive evaluation of high temporal- and spatial-resolution cardiac CT using a wide coverage system (CONVERGE) registry (a multicenter registry at four centers) have shown the 16 cm CT scanner having a better image quality in comparison to the 4 cm scanner. However, these studies failed to include patients with undesirable or high heart rates due to well-documented poor image acquisition on prior generations of CCTA scanners. Methods: A prospective, observational, multicenter cohort study comparing image quality, quantitively and qualitatively, on scans performed on a 16 cm CCTA in comparison to a cohort of images captured on a 4 cm CCTA at four centers. Participants were recruited based on broad inclusion criteria, and each patient in the 16 cm CCTA arm of the study received a CCTA scan using a 256-slice, whole-heart, single-beat scanner. These patients were then matched by age, gender, and heart rate to patients who underwent CCTA scans on a 4 cm CT scanner. Image quality was graded based on the signal-to-noise ratio, contrast-to-noise ratio, and on a Likert scale of 0–4: 0, very poor—4, excellent. Results: 104 patients were evaluated for this study. The mean heart rate was 75 ± 7 in the 4 cm scanner and 75 ± 7 in the 16 cm one (p = 0.426). The signal-to-noise and contrast-to-noise ratios were higher in the 16 cm scanner (p = 0.0001). In addition, more scans were evaluated as having an excellent quality on the 16 cm scanner than on the 4 cm scanner (p < 0.0001) based on a 4-point Likert scale. Conclusions: The 16 cm scanner has a superior image quality for fast heart rates compared to the 4 cm scanner. This study shows that there is a significantly higher frequency of excellent and good studies showing better contrast-to-noise and signal-to-noise ratios with the 16 cm scanner compared to the 4 cm scanner.

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Chindasombatjaroen, Jira, Naoya Kakimoto, Hiroaki Shimamoto, Shumei Murakami e Souhei Furukawa. "Correlation Between Pixel Values in a Cone-Beam Computed Tomographic Scanner and the Computed Tomographic Values in a Multidetector Row Computed Tomographic Scanner". Journal of Computer Assisted Tomography 35, n. 5 (settembre 2011): 662–65. http://dx.doi.org/10.1097/rct.0b013e31822d9725.

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Più fonti

Tesi sul tema "Tomographic scanner"

Laurendeau, Matthieu. "Tomographic incompleteness maps and application to image reconstruction and stationary scanner design". Electronic Thesis or Diss., Lyon, INSA, 2024. http://www.theses.fr/2024ISAL0130.

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La tomographie par rayons X est l'une des modalités d'imagerie les plus couramment utilisées dans les domaines médical et industriel. Ces dernières années, de nouvelles sources à rayons X ont été développées sur la base de cathodes en nanotubes de carbone (CNT). Leur taille compacte permet de concevoir une nouvelle génération de scanner multi-sources. Contrairement aux systèmes traditionels dotés d'une seule source mobile, ces scanners adoptent des architectures stationnaires où plusieurs sources sont fixées à des positions précises. Cela profiterait à la fois à l'industrie, avec des scanners moins chers, et aux applications médicales, avec des scanners légers et mobiles qui pourraient être déployés directement sur les sites d'urgence. Cependant, ce type de scanner a une couverture angulaire limitée, posant des défis importants en reconstruction d'images. Cette thèse se concentre sur la conception de tels scanners stationnaires. Trois axes d'étude sont examinés. La première contribution est le développement d'une métrique indépendante de l'objet, afin d'évaluer la capacité de reconstruction d'une géométrie de scanner. Basée sur la condition de Tuy, la métrique évalue l'incomplétude tomographique locale et est visualisée selon des cartes de champs vectoriels 3D. Elle est ensuite améliorée pour traiter les projections tronquées, la rendant plus applicable aux configurations du monde réel. Ces cartes permettent de classer différentes géométries, de prédire la qualité de reconstruction et d'identifier l'origine des artefacts géométriques. Elle est calculée pour une variété de géométries, y compris des scanners existants. La seconde est une nouvelle méthode de régularisation locale qui permet de relever les défis de la reconstruction à angle limité. Basée sur une régularisation de type variation totale directionnelle (DTV), la méthode adapte la force et les poids directionnels à chaque voxel sélectionné à partir de la métrique introduite précédemment. Deux approches sont explorées : des poids directionnels basés sur le ratio par rapport aux axes de l'image ou basés sur l'ellipse. L'algorithme de reconstruction est évalué dans des simulations 2D et 3D, en considérant des données bruitées et non bruitées, ainsi que des données réelles. La troisième est un outil d'optimisation de la géométrie des scanners. Étant donné un nombre fixe de sources et une surface disponible pour leur positionnement, l'outil optimise l'emplacement des sources en minimisant l'incomplétude tomograhique de la région imagée. Plusieurs algorithmes d'optimisation sont implémentés et testés sur des scénarios simples 2D et 3D
Computed tomography (CT) is one of the most commonly used modality for three-dimensional (3D) imaging in the medical and industrial fields. In the past few years, new X-ray sources have been developed based on carbon nanotube (CNT) cathodes. Their compact size enables the design of a new generation of multi-source CT scanners. In contrast to traditional systems with a single moving source, these scanners often adopt stationary architectures where multiple sources are static. It would benefit both industry with cheaper and motionless systems and medical applications with light-weight and mobile scanners which could be brought to emergency sites. However, this type of scanner uses a fewer number of measurements, known as projections, and may acquire data with a limited range of angles, leading to well-known image reconstruction challenges. This thesis focuses on the design of such stationary CT scanners. Three axes of study were investigated. The first contribution is the development of an object-independent metric to assess the reconstruction capability of a given scanning geometry. Based on Tuy's condition, the metric evaluates local tomographic incompleteness and is visualized through 3D vector field maps. It is further extended to handle truncated projections, improving its applicability to real-world configurations. The metric enables ranking different geometries, predicting image quality reconstruction, and identifying the origin of geometric artifacts. It is applied to a variety of geometries, including existing scanners. The second is a novel local regularization method to address limited-angle reconstruction challenges. The method employs a directional total variation (DTV) regularizer whose strength and directional weights are adaptively selected at each voxel. The weights are determined based on the previously introduced metric. Two approaches for directional weights were explored: ratio-based weighting relative to image axes and ellipse-based weighting. The reconstruction algorithm is evaluated in both 2D and 3D simulations, considering noiseless and noisy data, as well as real data. The third is a tool for optimizing the geometry of CT scanners. Given a fixed number of sources and the surface area available for their positions, the tool optimizes the placement of sources based on the proposed metric. Several state-of-the-art optimization algorithms were implemented and tested on simple 2D and 3D scenarios

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Heathcote, Alan D. "The dual development of an optical tomographic scanner and three dimensional gel dosimeter for complex radiotherapy verification". Thesis, University of Hull, 2008. http://hydra.hull.ac.uk/resources/hull:764.

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The state-of-the-art radiotherapy delivery treatments available today require that the intended dose distributions delivered are verified by volumetric gel dosimetry. The development of tissue equivalent gel dosimeters that provide an integrated assessment of the dynamic treatments, are primarily imaged with Magnetic Resonance Imaging (MRI). This thesis describes the dual development and assessment of an optical tomographic scanner and normoxic gel dosimeter. MRI centers are currently limited in both time and resources in providing the routine imaging necessary for treatment verification. An alternative bench top imaging modality has been designed, built and developed to provide both complementary and comparable observations to MRI. It is hoped that this cost effective optical imaging system could alleviate this technological reliance. The optical tomography scanner is evaluated from a series of investigations into the capabilities and limitations of optical tomographic imaging used in conjunction with gel dosimetry. Previously, the manufacture of gel dosimeters required anoxic environments in which the presence of oxygen in the dosimeter is limited. This requirement limited the production of gel dosimeters to chemistry laboratories that possessed the required technical expertise. MRI and optical imaging have been used to investigate the properties, dose response and the batch-to-batch reproducibility of a normoxic MAGIC gel dosimeter. The results obtained are encouraging having shown successfully reconstructed optical images obtained from various dose distributions delivered to the MAGIC gel dosimeter.

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BARUFFALDI, FILIPPO. "Development of a Proton Tomography scanner". Doctoral thesis, Università degli studi di Padova, 2022. http://hdl.handle.net/11577/3455159.

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iMPACT, innovative Medical Proton Achromatic Calorimeter and Tracker, is a University of Padova and INFN research project, funded by the European Research Council. The project aims to design, develop and prototype a fast and accurate proton Computed Tomography (pCT) Scanner, with the ultimate goal of demonstrating the technology necessary to realize a clinically viable pCT system. The overall development, current state, and projected performances of the scanner will be illustrated and discussed. Monte Carlo simulation, a selection of data collected with cosmic rays, and tests with a proton beam will be reviewed as well to quantitatively assess the performance of the apparatus. Preliminary studies on proton track reconstruction, based on a Maximum Likelihood path formalism, will be also presented, together with a supporting object shape identification algorithm. The iMPACT scanner is essentially made by a multi-layer silicon pixels sensors tracker stage using the ALPIDE sensors, and a scintillators-based range calorimeter. There will be an in-depth review of the innovative, highly segmented structure of the calorimeter, based on multiple, orthogonal scintillating elements, and of its read-out architecture, which exploits massive FPGAs parallelism and distributed memory to achieve the triggering and data collection performance necessary to cope with the extremely high event-rate requested by pCT applications. On the tracker side, an overview of the ALPIDE sensor, developed within the ALICE Collaboration for its Inner Tracking System (ITS), and currently adopted for the prototyping phase of the iMPACT tracker, will be illustrated as well, together with the general tracker layout and operations. In parallel, in order improve upon the techniques and methods used in particle physics for tracking purposes, specific studies have been performed to optimize the ALICE ITS alignment, which results will be also presented. Finally, a brief mention will be given to the INFN project ARCADIA, focused on the development of innovative Monolithic Active Pixel Sensors characterized by fully depleted substrate to improve the charge collection efficiency and timing characteristics over a wide range of operational and environmental conditions. The iMPACT project in fact plans to employ the ARCADIA technology to build a pixel detector more suited for the pCT application respect to the ALPIDE sensor.
iMPACT, innovative Medical Proton Achromatic Calorimeter and Tracker, is a University of Padova and INFN research project, funded by the European Research Council. The project aims to design, develop and prototype a fast and accurate proton Computed Tomography (pCT) Scanner, with the ultimate goal of demonstrating the technology necessary to realize a clinically viable pCT system. The overall development, current state, and projected performances of the scanner will be illustrated and discussed. Monte Carlo simulation, a selection of data collected with cosmic rays, and tests with a proton beam will be reviewed as well to quantitatively assess the performance of the apparatus. Preliminary studies on proton track reconstruction, based on a Maximum Likelihood path formalism, will be also presented, together with a supporting object shape identification algorithm. The iMPACT scanner is essentially made by a multi-layer silicon pixels sensors tracker stage using the ALPIDE sensors, and a scintillators-based range calorimeter. There will be an in-depth review of the innovative, highly segmented structure of the calorimeter, based on multiple, orthogonal scintillating elements, and of its read-out architecture, which exploits massive FPGAs parallelism and distributed memory to achieve the triggering and data collection performance necessary to cope with the extremely high event-rate requested by pCT applications. On the tracker side, an overview of the ALPIDE sensor, developed within the ALICE Collaboration for its Inner Tracking System (ITS), and currently adopted for the prototyping phase of the iMPACT tracker, will be illustrated as well, together with the general tracker layout and operations. In parallel, in order improve upon the techniques and methods used in particle physics for tracking purposes, specific studies have been performed to optimize the ALICE ITS alignment, which results will be also presented. Finally, a brief mention will be given to the INFN project ARCADIA, focused on the development of innovative Monolithic Active Pixel Sensors characterized by fully depleted substrate to improve the charge collection efficiency and timing characteristics over a wide range of operational and environmental conditions. The iMPACT project in fact plans to employ the ARCADIA technology to build a pixel detector more suited for the pCT application respect to the ALPIDE sensor.

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Yao, Yongjia. "Wearable sensor scanner using electrical impedance tomography". Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600214.

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Electrical impedance tomography (EIT) is an imaging system that can generate a map of electrical conductivity. The aim of this project is to develop a pressure mapping imaging device, which we also call Wearable Scanners using EIT (WSEIT) system. WSEIT are being developed based on electrical conductivity imaging of the conductive area generated in a fabric structure. This thesis demonstrates the application of conductive fabric as a pressure mapping imaging device together with the EIT imaging system. For the first time, multiple-deformation and pressure points are detected. This thesis will also show quantitative analysis of this pressure mapping imaging solution. We envisage a number of applications for WSEIT, especially in the areas of robotics and bio-mechanics. In this project, we are interested in measuring the pressure that has been applied to a 2D surface. There are three major parts to this project: the sensor design, the hardware electronics and, finally, tomographic image reconstruction. The sensors are elastomeric conductive areas that can be integrated in a number of ways into a garment. It will be shown that the conductivity of the area will change as the surface topology changes; as pressure is applied, the electrical impedances of the sensor area are measured from a number of peripheral points. The impedance data is then transferred to the image reconstruction software. Finally, the inversion technique is applied to the data to generate a pressure and deformation map of the body. The measurement system has been developed using a multiplexer circuit and a USB-based DAQ card, from National Instruments (NI). The performance of the EIT system was tested using traditional saline phantoms. Several different types of materials have been considered and tested for the design of fabric based pressure sensor.

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BARUFFALDI, FILIPPO. "Development of a proton computed tomography scanner". Doctoral thesis, Università degli studi di Padova, 2022. http://hdl.handle.net/11577/3453783.

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Bergeron, Mélanie. "Construction et expérimentation d'un scanner bimodal TEP/TDM combiné de résolution spatiale submillimétrique pour petits animaux". Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/6755.

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Résumé : La tomographie d’émission par positrons (TEP) permet une imagerie fonctionnelle et moléculaire qui peut bénéficier de l’utilisation conjointe de la tomodensitométrie (TDM), d’abord pour fournir un support anatomique aux images TEP, mais aussi pour permettre une correction plus précise des images TEP. Les appareils existants sont composés de deux scanners juxtaposés nécessitant un déplacement du sujet entre les deux acquisitions, ce qui peut causer des artéfacts de mouvement dans l’image fusionnée TEP/TDM. De plus, le mode de fonctionnement des scanners TDM, basé sur l’intégration du flux de rayons X, délivre une dose de radiations relativement élevée qui peut interférer avec la réalisation d’études/protocoles d’imagerie longitudinales. La réalisation d’un appareil TEP/TDM partageant le même système de détection basé sur le détecteur LabPET II pourrait remédier à ces problèmes. Dans un premier temps, le module de détection LabPET II a été caractérisé pour la TEP et la TDM. Les premières études d’imagerie TDM avec ce détecteur ont aussi été conduites avec un simulateur. Ce travail a permis de déceler un phénomène de diaphonie optique au sein du module de détection. La recherche d’une solution à ce problème a motivé l’évaluation de nouveaux types de réflecteurs métallisés, donc plus opaques, pour en limiter les effets. Le signal relativement faible détecté en TDM a par la suite mené à explorer des scintillateurs alternatifs présentant un rendement lumineux supérieur. L’un de ces scintillateurs permettra d’améliorer sensiblement les performances du scanner LabPET I et pourrait être retenu pour la génération future de scanners LabPET II. || Abstract : Positron emission tomography (PET) provides functional and molecular imaging capabilities that can benefit from joint use with computed tomography (CT), first to provide anatomical support to PET images, but also to allow a more precise correction of PET images. Existing devices are composed of two back-to-back scanners which require displacing the subject between the two acquisitions, possibly causing motion artifacts in the fused PET/CT images. Moreover, the operation mode of CT scanners based on the X-ray signal integration delivers a relatively high radiation dose that can interfere with longitudinal imaging studies/protocols. The realization of a PET/CT scanner sharing the same detection system for both 511 keV and X-ray photons and based on the LabPET II could remedy these problems. As a first step, a characterization of the detection module LabPET II was performed in PET and CT mode. The first CT imaging studies with this detector were also conducted with a simulator. This work allowed identifying an optical crosstalk phenomenon in the detection module. The search for a solution to this problem has motivated the evaluation of new types of metallized, more opaque, reflectors to limit crosstalk effects. The relatively low signal detected in CT led us to explore alternative scintillators having a higher light output. One of these scintillators will significantly improve the performance of the LabPET I scanner and could be used for the next generation of LabPET II scanners.

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Kemgue, Alain Trésor. "Modélisation des formes volumiques complexes par des volumes quadriques. Application à la représentation de l'espace poral du sol à partir des images tomographiques 3D". Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS158.pdf.

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Les structures naturelles sont constituées de formes complexes qui sont pour la plupart difficiles à modéliser avec de simples équations analytiques. La complexité de la représentation est due à l'hétérogénéité du milieu physique et à la variété des phénomènes impliqués. Nous nous intéressons dans notre étude à la représentation des structures volumiques complexes issues des images tomographiques. Grâce aux récentes avancées technologiques en tomographie assisté par ordinateur, l’acquisition d'images de formes avec les scanners est maintenant possible. Cependant, ces données images, constituées de voxels, ne sont pas directement utilisables pour simuler un certain nombre de phénomènes. Dans cette thèse, nous proposons une approche de modélisation de ces formes qui consiste à effectuer une approximation par morceaux des données images par des volumes quadriques. Nous proposons d'utiliser une stratégie de division-fusion et un algorithme de croissance de régions pour optimiser une fonctionnelle incluant à la fois un terme erreur d'approximation et un facteur d'échelle. Les données en entrée de notre algorithme sont un ensemble brut de voxels qui décrit une forme volumique complexe et le résultat en sortie est un ensemble de volumes quadriques tangents ou disjoints représentant la forme de départ de façon intrinsèque. Nous appliquons notre méthode pour représenter l'espace poral 3D du sol obtenu à partir des capteurs d'images tomographiques. Ainsi, dans ce contexte spécifique, nous validons notre modélisation géométrique en procédant aux simulations du drainage de l'eau et de l'activité de décomposition microbienne sur des données réelles d'échantillons de sol. Cette étude comporte plusieurs enjeux d’ordres écologique, agricole et industriel
Most of the natural shapes have complex volume forms that are usually difficult to model using simple analytical equations. The complexity of the representation is due to the heterogeneity of the physical environment and the variety of phenomena involved. In our study, we are interested by the complex volume shapes structures representation from computed tomographic images. Thanks to the technological advances in Computed Tomography scanners, the image acquisition of complex shapes becomes possible. However, these image data are not directly usable for simulation or modeling purposes. In this thesis, we investigate an approach of modeling of such shapes which consists in making a piecewise approximation of the image data by quadric volumes. We propose to use a split-merge strategy and a region growing algorithm to optimize a function that includes both an approximation error term and a scale factor term that is opposed to it. The input of our algorithms is voxel-based shape description and the result is a set of tangent or disjoint quadric volumes representing the shape in an intrinsic way. We apply our method to represent 3D soil pore space obtained from the Computed Tomography scanners. Within this specific context, we validate our geometrical modeling by performing simulations of water draining and microbial decomposition activities on real data soil sample. This study involves several ecological, agricultural and industrial issues

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Louis, Nicolas Desgranges Pascal. "Étude au scanner multibarrettes des dissections aigues de type A opérées". Créteil : Université de Paris-Val-de-Marne, 2006. http://doxa.scd.univ-paris12.fr:80/theses/th0247917.pdf.

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Quatrehomme, Auréline. "Caractérisation des lésions hépatiques focales sur des acquisitions scanner multiphasiques". Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20207/document.

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L'évolution des techniques d'acquisition des imageries médicales et leur importance de plus en plus grande dans la prise en charge du patient (diagnostic, préparation d'intervention, suivi, etc.), font émerger de nouveaux besoins autour du traitement informatique des images. La reconnaissance du type de lésions hépatiques est un grand enjeu, notamment car le cancer du foie, létal et très répandu, est souvent diagnostiqué trop tard pour sauver le patient. C'est dans ce cadre qu'est né le projet de recherche de ce manuscrit, fruit d'une collaboration entre la société IMAIOS et le Laboratoire d'Informatique, de Robotique et de Microélectronique de Montpellier (LIRMM).Cette thèse présente un système complet et automatique permettant, à partir d'images de lésions au format médical DICOM, d'extraire des descripteurs visuels de divers nodules hépatiques puis de les différencier à l'aide de ces derniers. Les contributions décrites s'articulent autour de divers axes : normalisation des niveaux de gris des images de lésions par rapport au foie sain, proposition, analyse et tests de descripteurs visuels (s'appuyant notamment sur les informations temporelles ou de densité des tissus), caractérisations diverses des différents types de lésions grâce à ces descripteurs et à un algorithme de classification. Les données sur lesquelles ces travaux ont été effectués sont des examens scanner multiphasiques
Medical imaging acquisition has taken benefits from recent advances and is becoming more and more important in the patient care process. New needs raise, which are related to image processing. Hepatic lesion recognition is a hot topic, especially because liver cancer is wide-spread and leads to death, most of the time because of the diagnosis which is made too late. In this context is born this manuscrit research project, a collaboration between IMAIOS company and the Laboratory of Informatics, Robotics and Micro-electronics ofMontpellier (LIRMM).This thesis presents a complete and automated system that extracts visual features from lesion images in the medical format DICOM, then differenciate them on these features.The various described contributions are: intensity normalization using healthy liver values, analysis and experimentations around new visual features, which use temporal information or tissue density, different kind of caracterisation of the lesions. This work has been done on multi-phase Computed Tomography acquisitions

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McFarland, Sheila J. "Development of a prototype scanner for pulsed ultrasound computed tomography". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61142.pdf.

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Libri sul tema "Tomographic scanner"

L, Arrivé, a cura di. Guide d'interprétation en scanner. Paris: Masson, 2001.

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Lionel, Arrivé, a cura di. Guide d'interprétation en scanner. 3^a ed. Paris: Masson, 2005.

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Olivier, Vigneaux, a cura di. Imagerie cardiaque: Scanner et IRM. Issy-les-Moulineaux: Masson, 2005.

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Canadian Coordinating Office for Health Technology Assessment. A comparison of fixed and mobile CT and MRI scanners. Ottawa, Ont: The Office, 1995.

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Trajtenberg, Manuel. Economic analysis of product innovation: The case of CT scanners. Cambridge, Mass: Harvard University Press, 1990.

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Jacqueline, Vignaud, Jardin Caroline e Rosen Lawrence, a cura di. The ear, diagnostic imaging: CT scanner, tomography, and magnetic resonance. New York: Masson Pub., U.S.A., 1986.

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Caroline, Jardin, Rosen Lawrence e Vignaud Jacqueline, a cura di. The ear, diagnostic imaging: CT scanners, tomography and magnetic resonance. New York: Masson Pub., 1986.

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K, Fishman Elliot, e Jeffrey R. Brooke, a cura di. Multidetector CT: Principles, techniques, and clinical applications. Philadelphia: Lippincott Williams & Wilkins, 2004.

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Hsieh, Jiang. Computed tomography: Principles, design, artifacts, and recent advances. Bellingham, Washington: SPIE, 2015.

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1930-, Stanford William, e Rumberger John A, a cura di. Ultrafast computed tomography in cardiac imaging: Principles and practice. Mount Kisco, NY: Futura Pub. Co., 1992.

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Capitoli di libri sul tema "Tomographic scanner"

Williams, Mark B., Patricia G. Judy, Mitali J. More, Jennifer A. Harvey, Stan Majewski, James Proffitt, John McKisson et al. "Tomographic Dual Modality Breast Scanner". In Digital Mammography, 99–107. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-70538-3_15.

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Meerhoff, Walter, e Guillermo Meerhoff. "Variability of topographic measurements after trabeculectomy in primary angle closure glaucoma with the laser tomographic scanner". In Laser Scanning: Update 1, 29–35. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0322-3_6.

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Knisely, J. P. S., L. Liu, M. J. Maryanski, M. Ranade, R. J. Schulz e J. C. Gore. "Three-Dimensional Dosimetry for Complex Stereotactic Radiosurgery Using a Tomographic Optical Density Scanner and BANG_TMPolymer Gels". In Radiosurgery 1997, 251–60. Basel: KARGER, 1997. http://dx.doi.org/10.1159/000062284.

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Raja, Aamir Y., Steven P. Gieseg, Sikiru A. Adebileje, Steven D. Alexander, Maya R. Amma, Fatemeh Asghariomabad, Ali Atharifard et al. "Spectral CT Imaging Using MARS Scanners". In Spectral, Photon Counting Computed Tomography, 117–38. First edition. | Boca Raton : CRC Press, 2020. | Series: Devices, circuits, & systems: CRC Press, 2020. http://dx.doi.org/10.1201/9780429486111-7.

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Barzas, Konstantinos, Shereen Fouad, Gainer Jasa e Gabriel Landini. "An Explainable Deep Learning Framework for Mandibular Canal Segmentation from Cone Beam Computed Tomography Volumes". In Lecture Notes in Computer Science, 1–13. Cham: Springer Nature Switzerland, 2025. https://doi.org/10.1007/978-3-031-82768-6_1.

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Abstract Cone Beam Computed Tomography (CBCT) is an indispensable imaging modality in oral radiology, offering comprehensive dental anatomical information. Accurate detection of the mandibular canal (MC), a crucial anatomical structure in the lower jaw, within CBCT volumes is essential to support clinical dentistry workflows, including diagnosis, preoperative treatment planning, and postoperative evaluation. In this study, we present a deep learning-based (DL) approach for MC segmentation using 3D U-Net and 3D Attention U-Net networks. We collected a unique dataset of CBCT scans from 20 anonymous hemisected mandibular bones, which were further processed for analysis. The samples were scanned using a CBCT scanner after inserting a wire through the whole length of the MC to identify its location in space (as a gold standard). Our experimental results demonstrate that the 3D Attention U-Net outperforms the standard 3D U-Net in detecting the MC’s location, with Dice similarity score, Precision, and Recall values of 0.65, 0.75, and 0.60, respectively. Unlike current DL-enabled methods for MC segmentation, which face deployment and trust challenges due to their “black-box” nature, our approach incorporates a post-hoc visual explainability feature through the Grad-CAM++ (Gradient-weighted Class Activation Mapping) algorithm. This tool highlights important regions within the CBCT volumes that influence the model’s predictions, providing valuable insights into the segmentation process, and bridging the gap between cutting-edge DL technology and clinical practice.

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Miroshnychenko, Oleksandra, Sergii Miroshnychenko, Boris Goldberg, Sergey Guzeev, Andrii Nevgasymyi e Yurii Khobta. "Veterinary Self-protected Cone-Beam Computed Tomography Scanner". In Lecture Notes in Networks and Systems, 237–47. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-03877-8_21.

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Russo, P., G. Mettivier, A. Lauria e M. C. Montesi. "A Laboratory Scanner for Cone Beam Breast Computed Tomography". In IFMBE Proceedings, 563–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03879-2_157.

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Kritikos, Michaela, Jan Urminsky e Ivan Buransky. "Comparison of Optical Scanner and Computed Tomography Scan Accuracy". In Lecture Notes in Mechanical Engineering, 521–30. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-90421-0_44.

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Cierniak, Robert. "Technical Concepts of X-ray Computed Tomography Scanners". In X-Ray Computed Tomography in Biomedical Engineering, 21–62. London: Springer London, 2011. http://dx.doi.org/10.1007/978-0-85729-027-4_3.

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Yamada, F., A. Tamaki e Y. Obara. "Assessment of Time-Space Evolutions of Intertidal Flat Geo-Environments Using an Industrial X-Ray CT Scanner". In Advances in Computed Tomography for Geomaterials, 343–51. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118557723.ch41.

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Atti di convegni sul tema "Tomographic scanner"

Vidal, Franck, Shaghayegh Afshari, Sharif Ahmed, Carolyn Atkins, Eric Béchet, Alberto Corbi Bellot, Stefan Bosse et al. "X-ray simulations with gVXR as a useful tool for education, data analysis, set-up of CT scans, and scanner development". In Developments in X-Ray Tomography XV, a cura di Bert Müller e Ge Wang, 30. SPIE, 2024. http://dx.doi.org/10.1117/12.3025315.

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Koo, Kyoungmo, Lucia Lee, Morgan McCloud e Mark Draelos. "Reducing cost but not quality with digital scanner interfaces for optical coherence tomography". In Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXIX, a cura di Rainer A. Leitgeb e Yoshiaki Yasuno, 77. SPIE, 2025. https://doi.org/10.1117/12.3044047.

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Zhang, Jingyue, Hu Zhang, Ting Hu, Zhe Li, Zhonghua Sun, Kebin Jia e Jinchao Feng. "Rotational Cherenkov-excited luminescence scanned tomography reconstruction with symmetry vision mamba". In Seventeenth International Conference on Photonics and Imaging in Biology and Medicine (PIBM 2024), a cura di Valery V. Tuchin, Qingming Luo e Lihong V. Wang, 36. SPIE, 2025. https://doi.org/10.1117/12.3057819.

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Quanhu, Zhang, Li Sufen, Hou Suxia, Zhang Lin e Zuo Wenming. "A Prototype of Tomographic Gamma Scanner". In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67372.

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Tomographic gamma scanning (TGS) method is one of the most advanced non-destructive assay (NDA) methods. TGS method can determine quantitatively with high accuracy transuranic nuclides in heterogeneously distributed media with medium- and high-density, and is thus widely used to assay the location and quantity of selected radioisotopes in scraps and wastes within sealed containers. In this paper, a prototype of tomographic gamma scanner which we designed is introduced. The TGS system is composed with four parts: external source with front collimator, radioactive material drum turning table, HPGe γ detector assembly including back collimator and cooling system, and computer. Successful implementation of the work has broken through the difficult problems or restraints to the development and applications of TGS, it will be applied widely to the non-destructive assay of nuclear materials within sealed container in the nuclear safeguards, radwaste measurement and arms control fields.

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Weiss Cohen, Miri, John A. Kennedy, Archil Pirmisashvili e Gleb Orlikov. "An Automatic System for Analyzing Phantom Images to Determine the Reliability of PET/SPECT Cameras". In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46254.

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This paper describes an automatic system for analyzing phantom images from two types of PET/CT scanners. The system was developed for the purpose of obtaining tomographic image quality parameters, which determine a number of different performance parameters, primarily scanner sensitivity, tomographic uniformity, contrast and spatial resolution. The system provides a method for generating and altering image masks used for the analysis of PET images, which are then automatically aligned with the PET data. The system automatically generates Quality Control (QC) reports and is currently being used at clinical PET/CT center.

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Mason, J. A., A. C. Tolchard, A. C. N. Towner, K. Burke, R. A. Price, S. Dittrich, F. Zurey e D. Walraven. "A Tomographic Segmented Gamma Scanner for the Measurement of Decommissioning Wastes". In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4658.

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The ANTECH Tomographic Segmented Gamma Scanner (TSGS) combines: a) Conventional Segmented Gamma Scanner (SGS) analysis (compliant to ASTM C1133-96), b) Tomographic Gamma Scanner (TGS) analysis providing both attenuation and source distribution maps (effectively 3D images) of the interior of drums, and c) Isotopic ratio analysis for uranium and transuranic elements using PC-FRAM. In SGS mode the drum is rotated and scanned segment by segment along its height. A two-pass measurement, one for transmission and one for emission, results in two spectra for each segment. An assay is made by measuring the intensity of a characteristic gamma ray from each nuclide. Corrections are made for count rate-related losses and attenuation by the item (using a transmission source). Calibration standards are used to provide the relationship between observed gamma-ray intensity and nuclide content. On completion, count rates are summed, and mass values for the nuclides of interest in the entire drum are calculated based on comparisons to appropriate calibration materials. In the case of SGS, the matrix is assumed to be homogeneous on a segment by segment basis. TGS involves measuring drums in segments as for SGS. However, in the case of TGS, while the drum is rotated, it is also moved in the horizontal direction (translated). Also, instead of taking a single large spectrum for each segment, 150 separate spectra are taken as the drum rotates and is translated. These 150 spectra are obtained both for transmission and for emission measurements. The 150 spectra taken for transmission constitute a set of data that can be solved to yield the distribution, or map of attenuation coefficients throughout the segment of the sample or drum. The measurement equations are over specified and the solution uses a maximum likelihood analysis. This results in the determination of a map (after a geometric transformation) of attenuation coefficients in a rectangular grid suitably superimposed on each segment. The attenuation map enables the operator to ‘visulise’ the variation of the density (governed by the collimator size and voxe resolution) in regions of the drum. This serves a non-destructive examination function similar to ‘real time radiography’ but with lower resolution. For the analysis of the emission data, the additional information obtained from the transmission data allows the emission data to be corrected for attenuation. This attenuation correction is the essential and important characteristic of TGS measurements not present in other gamma-ray measurement systems. For the first time in the case of the TGS, the map of attenuation is used to correct the measured source distribution in the matrix (segment by segment). The TSGS extends the range of gamma-ray measurement technology, as it is able to correctly determine the attenuation corrected radionuclide inventory in heterogeneous matrices where previous techniques such as the SGS are only applicable to homogeneous matrices. In the case of TGS a single calibration based on a non-interfering or empty matrix is made and then corrections relating back to this non-interfering matrix are made using the attenuation information determined from the transmission scan.

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Ravindranath, B., S. S. Junnarkar, M. L. Purschke, S. H. Maramraju, S. S. Southekal, S. P. Stoll, J. F. Pratte, P. Vaska, C. L. Woody e D. J. Schlyer. "3D tomographic wrist scanner for non-invasive determination of input function". In 2009 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2009). IEEE, 2009. http://dx.doi.org/10.1109/nssmic.2009.5401613.

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Qiao, H., T. G. Murthy e C. Saldana. "Structure and Deformation of Gradient Metal Foams Produced by Machining". In ASME 2019 14th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/msec2019-2980.

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Abstract The effects of surface structure on mechanical performance for open-cell aluminum foam specimens was investigated in the present study. A surface gradient for pore structure and diameter was introduced into open cell aluminum foams by machining-based processing. The structure changes in the strut and pore network were evaluated by computed tomography characterization. The role of structure gradients in affecting mechanical performance was determined using digital volume correlation and in situ compression within the computed tomographic scanner. These preliminary results show that the strength of these materials may be enhanced through surface structural gradients.

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Bille, J. F., e S. I. Brown. "3D Imaging Of The Human Eye Using The Laser Tomographic Scanner Lts". In 14th Congress of the International Commission for Optics, a cura di Henri H. Arsenault. SPIE, 1987. http://dx.doi.org/10.1117/12.967146.

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Troiani, Francesco, Nadia Cherubini, Alessandro Dodaro, Franco Vittorio Frazzoli e Romolo Remetti. "L/ILW Waste Characterisation by the ENEA Multi-Technique Gamma System SRWGA". In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4730.

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The SEA Radioactive Waste Gamma Analyser (SRWGA), is the gamma assay system of the ENEA Laboratory for L/ILW Waste Characterisation, which started operating in 1996 as a simple gamma scanner and has been under a continuous improvement process to became a multi-techniques system. The SRWGA is designed for the assay of radioactive waste drums containing gamma emitting nuclides. The system operates with an XtRa (extended range) Ge coaxial detector. This is liquid nitrogen colled, and shielded by means of a lead cylinder with two collimation windows; one mixed transmission source is provided. The system allows the application of four different measuring techniques, each one with its peculiar field of application, depending on waste characteristics or measuring time: Open Geometry, Segmented Gamma Scanning (with multi-energy transmission correction), Angular Scanning and, recently, Low Resolution Emission and Transmission Tomography, as the SRWGA is now endowed with new mechanical motions systems for tomographic capabilities. Tomographic reconstructions are obtained by means of a backprojection filtered by convolution methods (for transmission tomography) and Best Likelihood Maximisation (for emission tomography). The information obtained with transmission and emission tomography allows the localisation of matrix dishomogeneities and hot spots, carrying out a strong reduction of total activity uncertainties. This work presents the experimental results obtained using certified γ sources located in known matrices.

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Rapporti di organizzazioni sul tema "Tomographic scanner"

Mercer, David J. Tomographic Gamma Scanner Experience: Three Cases. Office of Scientific and Technical Information (OSTI), giugno 2014. http://dx.doi.org/10.2172/1136107.

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Estep, R. J., D. Miko, S. Melton e M. W. Rawool-Sullivan. A demonstration of the gross count tomographic gamma scanner (GC-TGS) method for the nondestructive assay of transuranic waste. Office of Scientific and Technical Information (OSTI), dicembre 1998. http://dx.doi.org/10.2172/335195.

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Karimi, S., e H. Martz. Dose Measurement on Microfocus Computed Tomography Scanner. Office of Scientific and Technical Information (OSTI), aprile 2024. http://dx.doi.org/10.2172/2375414.

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Roberson, G. P., e C. M. Logan. Estimate of external background radiation interference on a tomography scanner. Office of Scientific and Technical Information (OSTI), luglio 2000. http://dx.doi.org/10.2172/15003405.

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Lin, Pei-Jan Paul, Thomas J. Beck, Caridad Borras, Gerald Cohen, Robert A. Jucius, Robert J. Kriz, Edward L. Nickoloff et al. Specification and Acceptance Testing of Computed Tomography Scanners. AAPM, 1993. http://dx.doi.org/10.37206/38.

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Kaplan, Daniel, Kenneth Gibbs, Abdullah Mamun e Brian Powell. Non-Destructive Imaging of a Liquid Moving Through Porous Media Using a Computer Tomography Scanner. Office of Scientific and Technical Information (OSTI), agosto 2020. http://dx.doi.org/10.2172/1647017.

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Atherosclerosis Biomarkers by Computed Tomography Angiography (CTA). Chair Andrew Buckler, Luca Saba e Uwe Joseph Schoepf. Radiological Society of North America (RSNA) / Quantitative Imaging Biomarkers Alliance (QIBA), marzo 2023. http://dx.doi.org/10.1148/qiba/20230328.

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The clinical application of Computed Tomography Angiography (CTA) is widely available as a technique to optimize the therapeutic approach to treating vascular disease. Evaluation of atherosclerotic arterial plaque characteristics is currently based on qualitative biomarkers. However, the reproducibility of such findings has historically been limited even among experts (1). Quantitative imaging biomarkers have been shown to have additive value above traditional qualitative imaging metrics and clinical risk scores regarding patient outcomes (2). However, many definitions and cut-offs are present in the current literature; therefore, standardization of quantitative evaluation of CTA datasets is needed before becoming a valuable tool in daily clinical practice. To establish these biomarkers in clinical practice, techniques are required to standardize quantitative imaging across different manufacturers with cross-calibration. Moreover, the post-processing of atherosclerotic plaque segmentation needs to be optimized and standardized. The goal of a Quantitative Imaging Biomarker Alliance (QIBA) Profile is to provide an implementation guide to generate a biomarker with an effective level of performance, mostly by reducing variability and bias in the measurement. The performance claims represent expert consensus and will be empirically demonstrated at a subsequent stage. Users of this Profile are encouraged to refer to the following site to understand the document’s context: http://qibawiki.rsna.org/index.php/QIBA_Profile_Stages. All statistical performance assessments are stated in carefully considered metrics and according to strict definitions as given in (3-8), which also includes detailed, peer-reviewed rationale on the importance of adhering to such standards. The expected performance is expressed as Claims (Section 1.2). To achieve those claims, Actors (Scanners, Reconstruction Software, Image Analysis Tools, Imaging Physicians, Physicists, and Technologists) must meet the Checklist Requirements (Section 3) covering Subject Handling, Image Data Acquisition, Image Data Reconstruction, Image QA, and Image Analysis. This Profile is at the Clinically Feasible stage (qibawiki.rsna.org/index.php/QIBA_Profile_Stages) which indicate that multiple sites have performed the Profile and found it to be practical and expect it to achieve the claimed performance. QIBA Profiles for other CT, MRI, PET, and Ultrasound biomarkers can be found at qibawiki.rsna.org

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Saba, Luca, e Uwe Joseph Schoepf. Atherosclerosis Biomarkers by Computed Tomography Angiography (CTA) - Maintenance version June 2024. Chair Andrew Buckler. Radiological Society of North America (RSNA) / Quantitative Imaging Biomarkers Alliance (QIBA), giugno 2024. http://dx.doi.org/10.1148/qiba/202406.

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The clinical application of Computed Tomography Angiography (CTA) is widely available as a technique to optimize the therapeutic approach to treating vascular disease. Evaluation of atherosclerotic arterial plaque characteristics is currently based on qualitative biomarkers. However, the reproducibility of such findings has historically been limited even among experts. Quantitative imaging biomarkers have been shown to have additive value above traditional qualitative imaging metrics and clinical risk scores regarding patient outcomes. However, many definitions and cut-offs are present in the current literature; therefore, standardization of quantitative evaluation of CTA datasets is needed before becoming a valuable tool in daily clinical practice. To establish these biomarkers in clinical practice, techniques are required to standardize quantitative imaging across different manufacturers with cross-calibration. Moreover, the post-processing of atherosclerotic plaque segmentation needs to be optimized and standardized. The goal of a Quantitative Imaging Biomarker Alliance (QIBA) Profile is to provide an implementation guide to generate a biomarker with an effective level of performance, mostly by reducing variability and bias in the measurement. The performance claims represent expert consensus and will be empirically demonstrated at a subsequent stage. Users of this Profile are encouraged to refer to the following site to understand the document’s context: http://qibawiki.rsna.org/index.php/QIBA_Profile_Stages. All statistical performance assessments are stated in carefully considered metrics and according to strict definitions as given in (3-8), which also includes detailed, peer-reviewed rationale on the importance of adhering to such standards. The expected performance is expressed as Claims (Section 1.2). To achieve those claims, Actors (Scanners, Reconstruction Software, Image Analysis Tools, Imaging Physicians, Physicists, and Technologists) must meet the Checklist Requirements (Section 3) covering Subject Handling, Image Data Acquisition, Image Data Reconstruction, Image QA, and Image Analysis. This Profile is at the Clinically Feasible stage (qibawiki.rsna.org/index.php/QIBA_Profile_Stages) which indicate that multiple sites have performed the Profile and found it to be practical and expect it to achieve the claimed performance. QIBA Profiles for other CT, MRI, PET, and Ultrasound biomarkers can be found at qibawiki.rsna.org.

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Gantzer, Clark J., Shmuel Assouline e Stephen H. Anderson. Synchrotron CMT-measured soil physical properties influenced by soil compaction. United States Department of Agriculture, febbraio 2006. http://dx.doi.org/10.32747/2006.7587242.bard.

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Methods to quantify soil conditions of pore connectivity, tortuosity, and pore size as altered by compaction were done. Air-dry soil cores were scanned at the GeoSoilEnviroCARS sector at the Advanced Photon Source for x-ray computed microtomography of the Argonne facility. Data was collected on the APS bending magnet Sector 13. Soil sample cores 5- by 5-mm were studied. Skeletonization algorithms in the 3DMA-Rock software of Lindquist et al. were used to extract pore structure. We have numerically investigated the spatial distribution for 6 geometrical characteristics of the pore structure of repacked Hamra soil from three-dimensional synchrotron computed microtomography (CMT) computed tomographic images. We analyzed images representing cores volumes 58.3 mm³ having average porosities of 0.44, 0.35, and 0.33. Cores were packed with < 2mm and < 0.5mm sieved soil. The core samples were imaged at 9.61-mm resolution. Spatial distributions for pore path length and coordination number, pore throat size and nodal pore volume obtained. The spatial distributions were computed using a three-dimensional medial axis analysis of the void space in the image. We used a newly developed aggressive throat computation to find throat and pore partitioning for needed for higher porosity media such as soil. Results show that the coordination number distribution measured from the medial axis were reasonably fit by an exponential relation P(C)=10⁻C/C0. Data for the characteristic area, were also reasonably well fit by the relation P(A)=10⁻ᴬ/ᴬ0. Results indicates that compression preferentially affects the largest pores, reducing them in size. When compaction reduced porosity from 44% to 33%, the average pore volume reduced by 30%, and the average pore-throat area reduced by 26%. Compaction increased the shortest paths interface tortuosity by about 2%. Soil structure alterations induced by compaction using quantitative morphology show that the resolution is sufficient to discriminate soil cores. This study shows that analysis of CMT can provide information to assist in assessment of soil management to ameliorate soil compaction.

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Positron Emission Tomography-Scanner at Children`s Hospital of Michigan at Detroit, Michigan. Office of Scientific and Technical Information (OSTI), dicembre 1992. http://dx.doi.org/10.2172/10110463.

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