نتایج جستجو برای: object scatter

تعداد نتایج: 310250  

Afshin Akbarzadeh Hossein Ghadiri, Mohammad Rreza Ay, Saied Sarkar

Introduction: One of the most important parameters in x-ray CT imaging is the noise induced by detected scattered radiation. The detected scattered radiation is completely dependent on the scanner geometry as well as size, shape and material of the scanned object. The magnitude and spatial distribution of the scattered radiation in x-ray CT should be quantified for development of robust scatter...

2014
Donghak Shin Joon-Jae Lee Byung-Gook Lee

In this paper, we present a recognition method for a 3D object in scattering media by using the axially distributed sensing (ADS) method and nonlinear correlation operation. Since the scatter noise for a 3D object is recorded into the elemental images by ADS method, we apply a statistical image-processing algorithm to convert the scattering elemental images into the scatter-reduced ones. After ...

2012
Matthias Baer Michael Hammer Michael Knaup Ingomar Schmidt Ralf Christoph Marc Kachelrieß

The purpose of this study was to evaluate different approaches for scatter artifact reduction in the field of dimensional computed tomography (CT). The methods we investigated can be subdivided into one software-based method and three hardware-based methods. The software-based method uses a Monte Carlo scatter simulation to estimate scatter intensities for an initial model of the geometrical an...

Journal: :iranian journal of medical physics 0
afshin akbarzadeh ph.d. student, department of medical physics and biomedical engineering and research center for science and technology in medicine, tehran university of medical sciences, tehran, iran mohammad rreza ay assistant professor in biomedical engineering, biomedical systems & medical physics dept., tehran university of medical sciences & research center for science and technology in medicine, tehran, iran. hossein ghadiri ph.d. student, department of medical physics and biomedical engineering and research center for science and technology in medicine, tehran university of medical sciences, tehran, iran saied sarkar associate professor in biomedical engineering, biomedical systems & medical physics dept., tehran university of medical sciences & research center for science and technology in medicine, tehran, iran.

introduction: one of the most important parameters in x-ray ct imaging is the noise induced by detected scattered radiation. the detected scattered radiation is completely dependent on the scanner geometry as well as size, shape and material of the scanned object. the magnitude and spatial distribution of the scattered radiation in x-ray ct should be quantified for development of robust scatter...

Journal: :Medical physics 1997
M S Westmore A Fenster I A Cunningham

A new special-purpose computed tomographic (CT) imaging system is described which produces images based on measurements of the low-angle (0-10 degrees) x-ray diffraction properties of an object. Low-angle scatter in the diagnostic x-ray energy range is dominated by coherent scatter, and the system uses first-generation CT geometry to acquire a diffraction pattern for each pencil beam. The patte...

2017
Magnus Wrenninge Ryusuke Villemin Christophe Hery

An important distinction of diffusion models is that they only model multiple scattering. We generally distinguish between scatter events at different path depths: Zero-scatter events are photons that enter a surface and immediately reach an exit point without having scattered in the medium itself. Single scatter events do the same with a single interaction inside the volume. Multiple scatter e...

Introduction: In radionuclide imaging, object scatter is one of the major factors leading to image quality degradation. Therefore, the correction of scattered photons might have a great impact on improving the image quality. Regarding this, the present study aimed to determine the main and sub-energy windows for triple energy window (TEW) scatter correction method usin...

2016
Dongcai Hu Hao Chen Yuan Wang Yunbin Chen Zhou Xu

In the flat panel detector-based cone beam CT system, the scatter photons which reach the flat panel detector increase the detected signal, produce the image cupping artifact and reduce the image contrast. To conquer the X-Ray scatter problem, this study proposes the beam attenuation grid -based scatter correction algorithm that needs to add a beam attenuation grid (BAG) between the X-Ray sourc...

2002
P. Bristow A. Alexov F. Kerber M. Rosa

The dark flux correction step of the Faint Object Spectrograph calibration pipeline was investigated with the joint aims of applying a more physical model and improving the performance of the pipeline. After processing with the original calfos pipeline, dark calibration data shows a large scatter in count rates. We were able to reduce this scatter to some extent by scaling the correction accord...

2001
Chuanyong Bai Gengsheng L. Zeng Grant T. Gullberg

The modeling of 3D Compton scatter in SPECT is complicated by the use of a variety of collimator geometry. To date, effective and efficient modeling of 3D Compton scatter in parallel-beam SPECT has been made possible by Frey and Tsui [1], Zeng et al [2], and Bai et al [3]. For fan-beam and cone-beam SPECT, the model in [3] can effectively model first order 3D Compton scatter. But for varying-fo...

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