Consistency conditions and linear reconstruction methods in diffraction tomography

2000 ◽  
Vol 19 (1) ◽  
pp. 51-54 ◽  
Author(s):  
Xiaochuan Pan
Keyword(s):  
Diffraction Tomography ◽  
Consistency Conditions ◽  
Reconstruction Methods ◽  
Linear Reconstruction

scholarly journals A practical guideline for T1 reconstruction from various flip angles in MRI

2016 ◽  
Vol 10 (4) ◽  
pp. 213-223 ◽  
Author(s):  
Constantin Sandmann ◽  
Erlend Hodneland ◽  
Jan Modersitzki
Keyword(s):  
Sensitivity Analysis ◽  
Linear Method ◽  
Real Data ◽  
Flip Angle ◽  
Robust Method ◽  
Variable Flip Angle ◽  
Nonlinear Approach ◽  
Reconstruction Methods ◽  
The Family ◽  
Linear Reconstruction

A fast and robust method for T1 estimation in MRI is the so-called variable flip angle technique. We introduce a novel family of T1 reconstruction methods from data acquired with various flip angles and propose a family member which combines the robustness of a nonlinear- with the computational advantages of a linear reconstruction. The constructed family contains the most common approaches for T1 estimation, namely a linear and a nonlinear approach. A general sensitivity analysis for arbitrary members of the family is established. Advantages of the optimized reconstruction are demonstrated on phantom- as well as real data, showing improvements of up to 24% as compared with the linear method. As a further means to stabilize T1 estimation, spatial stabilization methods are compared. We demonstrate on phantom and on real data that improved results can be obtained if not only T1 but also a second unknown M0 in the reconstruction is stabilized.

Reconstruction and Prediction of Short-Crested Seas Based on the Application of a 3D-FFT on Synthetic Waves: Part 2 — Prediction

2012 ◽  
Author(s):  
E. Blondel-Couprie ◽  
P. Naaijen
Keyword(s):  
Fourier Transform ◽  
Specific Area ◽  
Wave Fields ◽  
Linear Waves ◽  
Reconstruction Methods ◽  
Analysis Technique ◽  
Specific Analysis ◽  
Spectral Components ◽  
Linear Reconstruction

This paper is the natural follow-up of the paper [6] also presented at OMAE 2012 by the authors. In [6] the authors describe various linear reconstruction methods for short-crested seas. Each of them is based on a specific analysis technique for the spectral components obtained when applying a 3D Fourier Transform to a series of snap shots of the ocean surface. The efficiency and the accuracy of each method is investigated in [6] for the reconstruction of synthetic images of linear short-crested wave fields. The purpose of the second part of the paper is to test the most accurate methods described in [6] for the prediction of synthetic linear waves. The predicted wave fields are calculated within a specific area in space and time called the prediction zone, which is determined theoretically. The method for determining the theoretical prediction zone is also described in this part of the paper.

scholarly journals Linear Reconstruction Methods for Large Thick Aperture Imaging

2018 ◽  
Vol 232 ◽  
pp. 02030
Author(s):  
Zhiming Yao ◽  
Baojun Duan ◽  
Weipeng Yan ◽  
Yan Song ◽  
Changcai Han ◽  
...  
Keyword(s):  
Blind Deconvolution ◽  
Wiener Filter ◽  
Source Image ◽  
Imaging Method ◽  
Reconstruction Method ◽  
Knife Edge ◽  
Ct Reconstruction ◽  
Reconstruction Methods ◽  
Linear Reconstruction ◽  
The Right

Large thick aperture imaging method is proposed to measure the radiation intensity distribution of radiation source whose size is several centimetres. The new method contains two steps which are coded imaging and image reconstruction. Geant4 is used to simulate the coded imaging process. Wiener filter, Lucy-Richardson, Regularized filter, blind deconvolution and CT reconstruction method are realized using Matlab software. Wiener filter and Regularized filter produce artifacts. CT reconstruction method can’t reveal the right size of 60Co-γ source because of the overlapping of knife edge images. Both L-R and blind deconvolution are effective. If the aperture is moved 0 mm, 2 mm, 4 mm, 6 mm along x-axis, the reconstruction result using L-R method has a larger correlation coefficient with source image. However, L-R method gets bad result if the aperture rotates more than 1.4°. Under this condition, blind deconvolution is the better choice.

High-resolution scanning electron microscopy (HRSEM) of mitochondria from various rat tissues

1988 ◽  
Vol 46 ◽  
pp. 14-15
Author(s):  
P.J. Lea ◽  
M.J. Hollenberg
Keyword(s):  
Electron Microscopy ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Rat Hepatocytes ◽  
Three Dimensions ◽  
Objective Lens ◽  
Rat Tissues ◽  
Thin Sections ◽  
Reconstruction Methods ◽  
Scanning Electron

Our current understanding of mitochondrial ultrastructure has been derived primarily from thin sections using transmission electron microscopy (TEM). This information has been extrapolated into three dimensions by artist's impressions (1) or serial sectioning techniques in combination with computer processing (2). The resolution of serial reconstruction methods is limited by section thickness whereas artist's impressions have obvious disadvantages.In contrast, the new techniques of HRSEM used in this study (3) offer the opportunity to view simultaneously both the internal and external structure of mitochondria directly in three dimensions and in detail.The tridimensional ultrastructure of mitochondria from rat hepatocytes, retinal (retinal pigment epithelium), renal (proximal convoluted tubule) and adrenal cortex cells were studied by HRSEM. The specimens were prepared by aldehyde-osmium fixation in combination with freeze cleavage followed by partial extraction of cytosol with a weak solution of osmium tetroxide (4). The specimens were examined with a Hitachi S-570 scanning electron microscope, resolution better than 30 nm, where the secondary electron detector is located in the column directly above the specimen inserted within the objective lens.

3-D reconstruction and analysis of mammalian mitotic spindle structure

1992 ◽  
Vol 50 (1) ◽  
pp. 578-579
Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh
Keyword(s):  
Cross Sections ◽  
Mitotic Spindle ◽  
Experimental Studies ◽  
Video Camera ◽  
Three Dimensions ◽  
Mitotic Spindles ◽  
Black And White ◽  
Reconstruction Methods ◽  
Spindle Structure ◽  
Tissue Culture Line

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.

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