نتایج جستجو برای: mlem algorithm
تعداد نتایج: 754023 فیلتر نتایج به سال:
A positron emission tomography (PET) scan does not measure an image directly. Instead, a PET scan measures a sinogram at the boundary of the field-ofview that consists of measurements of the sums of all the counts along the lines connecting the two detectors. Because there is a multitude of detectors built in a typical PET structure, there are many possible detector pairs that pertain to the me...
introduction: scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. accurate estimation of scatter in projection data of spect is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. methods: the objective of this paper is to develop and validate a scatter correction technique t...
Simulated measurements of traditional shipping container screening infrastructure based on large-area polyvinyl-toluene (PVT) or sodium-iodide detectors (NaI) are used alongside an iterative reconstruction algorithm to characterize the activity and location a radioactive point source concealed within loaded with cargo. A maximum likelihood expectation maximization method is employed reconstruct...
In emission tomography imaging, respiratory motion causes artifacts in lungs and cardiac reconstructed images, which lead to misinterpretations, imprecise diagnosis, impairing of fusion with other modalities, etc. Solutions like respiratory gating, correlated dynamic PET techniques, list-mode data based techniques and others have been tested, which lead to improvements over the spatial activity...
In inverse problems like tomography reconstruction we need to solve an over-determined linear system corrupted with noise. The MLEM algorithm finds the solution for Poisson noise as the fixed point of iterating a forward projection and a non-linear back projection. In tomography we have several hundred million equations and unknowns. The elements of the huge matrix are high-dimensional integral...
Accurate and robust tomographic reconstruction from dynamic positron emission tomography (PET) acquired data is a difficult problem. Conventional methods, such as the maximum likelihood expectation maximization (MLEM) algorithm for reconstructing the activity distribution-based on individual frames, may lead to inaccurate results due to the checkerboard effect and limitation of photon counts. I...
Synchrotron X-ray fluorescence (SXRF) microtomography has emerged as a powerful technique for the 3D visualization of the elemental distribution in biological samples. The mechanical stability, both of the instrument and the specimen, is paramount when acquiring tomographic projection series. By combining the progressive lowering of temperature method (PLT) with femtosecond laser sectioning, we...
UNLABELLED (111)In-Capromab pendetide imaging is indicated for postprostatectomy patients at risk for residual or recurrent disease. However, this study is complicated by relatively long times for tumor uptake and background washout that require imaging to be performed several days after radiopharmaceutical administration. In addition, (111)In-capromab pendetide demonstrates uptake in normal st...
objective(s): in spect, the sinogram contains scatter and lack of attenuated counts that degrade the reconstructed image quality and quantity. many techniques for attenuation and scatter correction have been proposed. an acceptable method of correction is to incorporate effects into an iterative statistical reconstruction. here, we propose new maximum likelihood expectation maximization (mlem) ...
Time-of-flight (TOF) positron emission tomography (PET) technology has recently regained popularity in clinical PET studies for improving image quality and lesion detectability. Using TOF information, the spatial location of annihilation events is confined to a number of image voxels along each line of response, thereby the cross-dependencies of image voxels are reduced, which in turns results ...
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