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Wyszukujesz frazę "X-ray method" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Simulation of computed tomography (CT) images using a Monte Carlo approach
Autorzy:
Wysocka-Rabin, A. M.
Qamhiyeh, S.
Jäkel, O.
Powiązania:
https://bibliotekanauki.pl/articles/147601.pdf
Data publikacji:
2011
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
X-ray tomography
Monte Carlo (MC) method
treatment planning
hadrontherapy
Opis:
Heavy ion treatment planning uses an empirical scanner-dependent calibration relation between computed tomography (CT) numbers and ion range. Any deviation in the values of CT numbers will cause a drift in the calibration curve of the CT scanner, which can reduce the accuracy of treatment beam delivery. To reduce uncertainty in the empirical estimation of CT numbers, we developed a simulation that takes into consideration the geometry, composition, and physical process that underlie their measurement. This approach uses Monte Carlo (MC) simulations, followed by a simple filtered back-projection reconstruction. The MC code used is BEAMnrc/EGSnrc. With the manufacturer’s permission, we simulated the components (X-ray tube, associated filters and beam shapers) of a Siemens Emotion CT. We then generated an initial beam shape and spectra, and performed further simulations using the phantom with substitutes. We analyzed the resulting phase space file to calculate projections, taking into account the energy response of the CT detectors. Then, we applied a simple reconstruction algorithm to the calculated projections in order to receive the CT image.
Źródło:
Nukleonika; 2011, 56, 4; 299-304
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo calculated CT numbers for improved heavy ion treatment planning
Autorzy:
Qamhiyeh, S.
Wysocka-Rabin, A.
Jäkel, O.
Powiązania:
https://bibliotekanauki.pl/articles/148658.pdf
Data publikacji:
2014
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
X-ray tomography
Monte Carlo (MC) method
treatment planning
hadrontherapy
Opis:
Better knowledge of CT number values and their uncertainties can be applied to improve heavy ion treatment planning. We developed a novel method to calculate CT numbers for a computed tomography (CT) scanner using the Monte Carlo (MC) code, BEAMnrc/EGSnrc. To generate the initial beam shape and spectra we conducted full simulations of an X-ray tube, filters and beam shapers for a Siemens Emotion CT. The simulation output files were analyzed to calculate projections of a phantom with inserts. A simple reconstruction algorithm (FBP using a Ram-Lak filter) was applied to calculate the pixel values, which represent an attenuation coefficient, normalized in such a way to give zero for water (Hounsfield unit (HU)). Measured and Monte Carlo calculated CT numbers were compared. The average deviation between measured and simulated CT numbers was 4 ± 4 HU and the standard deviation σ was 49 ± 4 HU. The simulation also correctly predicted the behaviour of H-materials compared to a Gammex tissue substitutes. We believe the developed approach represents a useful new tool for evaluating the effect of CT scanner and phantom parameters on CT number values.
Źródło:
Nukleonika; 2014, 59, 1; 15-23
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study on closed cell foam structure damage mechanisms
Autorzy:
Miedzińska, D.
Powiązania:
https://bibliotekanauki.pl/articles/246654.pdf
Data publikacji:
2012
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
closed cell foam
finite element method
X-ray tomography
damage
Opis:
Metallic foams are currently being looked at as a new material for automobiles. The main goal of the use of metallic foams in vehicles is to increase sound dampening, reduce the weight of the automobile, and increase energy absorption in case of crashes, or in military applications, to combat the concussive force of IEDs. The metallic foams that are being looked at currently, are aluminum and its alloys due to their low density (0.4-0.9 g/cm3). In addition these foams have a high stiffness, are fire resistant, do not give off toxic fumes, are fully recyclable, have high energy absorbance, have low thermal conductivity, have low magnetic permeability, and are efficient at sound dampening, especially in comparison to light weight hollow parts. In addition, partial addition of metallic foams in hollow parts of the car will decrease weakness points usually associated with car crashes and noisy vibrations. These foams are cheap to cast by using powder metallurgy (as compared to casting of other hollow parts). The aim of the research was to describe and to assess the main mechanisms that appear in the foam structure during the compression. The development process of the finite element model of the closed cell foam microstructure is presented in the paper. The model geometry was based on the real structure research, which was carried out with the use of computed tomography. The model was built with the use of a unique computer code created to transform the scan point cloud into FE raster model based on solid 8-node elements. The experimental and numerical compression test results were compared and showed good compatibility. The stress distributions were studied to describe the main mechanisms in the structure.
Źródło:
Journal of KONES; 2012, 19, 2; 321-327
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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