Search results for "RECONSTRUCTION"
showing 10 items of 784 documents
Comparaison de la mesure des déformations de fantômes de l’aorte à partir d’image obtenues par IRM et stéréovision
2015
International audience; The study of the wall strain distribution could be helpful to improve the decision criterion for surgery of aortic aneurysm. Recently, numerical simulations can complete the data obtained from imaging measurement in order to develop reliable models. However, the used medical imaging tools are not experimentally validated, in metrological point of view. The aim of this study focused on accuracy and reliability of measurement obtained from kinetic MR sequences. The measures of deformations from MRI were compare to those obtained from stereovision system. Cylindrical phantom of silicone material similar to arterial behavior simulated a symmetric aneurysm was designed. A…
Superresolved imaging in digital holography by superposition of tilted wavefronts
2006
A technique based on superresolution by digital holographic microscopic imaging is presented. We used a two dimensional (2-D) vertical-cavity self-emitting laser (VCSEL) array as spherical-wave illumination sources. The method is defined in terms of an incoherent superposition of tilted wavefronts. The tilted spherical wave originating from the 2-D VCSEL elements illuminates the target in transmission mode to obtain a hologram in a Mach-Zehnder interferometer configuration. Superresolved images of the input object above the common lens diffraction limit are generated by sequential recording of the individual holograms and numerical reconstruction of the image with the extended spatial frequ…
Holographically aided iterative phase retrieval
2012
Fourier transform holography (FTH) is a noise-resistant imaging technique which allows for nanometer spatial resolution x-ray imaging, where the inclusion of a small reference scattering object provides the otherwise missing phase information. With FTH, one normally requires a considerable distance between the sample and the reference to ensure spatial separation of the reconstruction and its autocorrelation. We demonstrate however that this requirement can be omitted at the small cost of iteratively separating the reconstruction and autocorrelation. In doing so, the photon efficiency of FTH can be increased due to a smaller illumination area, and we show how the presence of the reference p…
Optically-undistorted digital holographic microscopy for quantitative phase-contrast imaging
2011
We propose a telecentric architecture for circumventing, by a pure-optical method, the residual phase distortion inherent to standard configuration of digital holographic microscopy (DHM). With this proposal there is no need for computer compensation of the parabolic phase during the phase map recovering procedure. Futhermore, in off-axis configuration, the spatial frequency useful domain is enlarged. The validity of the method is demonstrated by performing quantitative measurements of depth differences
Based on Compton Camera
2016
Compton Cameras have been proposed as an alternative to SPECT imaging with Gamma Camera, mainly due to factors such as the electronic collimation, which allows a bigger field of view and provides further information from the acquired events if compared to devices with mechanical collimation. By contrast, this involves a higher amount of data to be processed. In medical devices this leads to waiting times that are generally higher than desirable by the health-care professionals. In this work we have assessed the reconstruction of Compton images by making use of iterative and non-iterative techniques, and also evaluated its performances as a SPECT imaging technique.
A mammographic phantom image reconstruction through Monte Carlo techniques
2005
Mammographic phantoms are employed during quality control test in breast screening locations and other health centres. These quality controls are performed to achieve the image quality required to detect breast abnormalities, ensuring the minimum risk to radiographied women. The aim of this study is the development of a methodology to reproduce the image of a mammogram during a routine exposure in a breast screening programme. In a first step, the CIRS 11A (MAMMO PHANTOM SP01) mammographic phantom has been simplified and modelled with the Monte Carlo transport code MCNP-4c2. Different tallies (F2 and F5) have been used to score the photon flux under the phantom, and a group of aluminium lay…
The Fluorescence Detector of the Pierre Auger Observatory
2010
The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detecto…
A method for detection of muon induced electromagnetic showers with the ANTARES detector
2012
The primary aim of ANTARES is neutrino astronomy with upward going muons created in charged current muon neutrino interactions in the detector and its surroundings. Downward going muons are background for neutrino searches. These muons are the decay products of cosmic-ray collisions in the Earths atmosphere far above the detector. This paper presents a method to identify and count electromagnetic showers induced along atmospheric muon tracks with the ANTARES detector. The method is applied to both cosmic muon data and simulations and its applicability to the reconstruction of muon event energies is demonstrated. © 2012 Elsevier B.V. All rights reserved.
Future Linear Colliders: Detector R&D, Jet Reconstruction and Top Physics Potential
2016
RESUMEN: Durante el siglo XX, los descubrimientos de nuevas partículas y las medidas realizadas en los colisionadores, junto con el progreso de la física teórica, nos permitieron formular el Modelo Estándar (SM) de las interacciones entre los constituyentes de la materia. El descubrimiento del bosón de Higgs en el LHC fue un gran paso en nuestra compren- sión de las interacciones fundamentales de la naturaleza y la estructura de la materia descrita por el Modelo Estándar. Con el fin de establecer el mecanismo de ruptura de simetría electrodébil, todas las propiedades del bosón de Higgs (masa, acoplamientos, amplitud de desintegración, espín) deben medirse con precisión. El LHC tiene excelen…
Stochastic description of traffic breakdown
2003
We present a comparison of nucleation in an isothermal-isochoric container with traffic congestion on a one-lane freeway. The analysis is based, in both cases, on the probabilistic description by stochastic master equations. Further we analyze the characteristic features of traffic breakdowns. To describe this phenomenon we apply the stochastic model regarding the jam emergence to the formation of a large car cluster on the highway.