On the Danger of Applying Statistical Reconstruction Methods in the Case of Missing Phase Information

1979 ◽  
pp. 95-101 ◽  
Author(s):  
J. C. Dainty ◽  
M. A. Fiddy ◽  
A. H. Greenaway
Keyword(s):  
Phase Information ◽  
Statistical Reconstruction ◽  
Reconstruction Methods

scholarly journals On the Danger of Applying Statistical Reconstruction Methods in the Case of Missing Phase Information

1979 ◽  
Vol 49 ◽  
pp. 95-101
Author(s):  
J.C. Dainty ◽  
M.A. Fiddy ◽  
A.H. Greenaway
Keyword(s):  
Fourier Transform ◽  
Real Data ◽  
Reconstruction Algorithm ◽  
Object Image ◽  
Reconstruction Algorithms ◽  
Phase Information ◽  
Object Reconstruction ◽  
Statistical Reconstruction ◽  
Reconstruction Methods ◽  
Actual Use

The use of entropy as a basis for object/image reconstruction procedures is not new, but with the appearance of new, faster algorithms the actual use of these algorithms for the reconstruction of objects from ‘real’ data is likely to increase.The purpose of this contribution is not to discourage such applications, but to illustrate that, under certain circumstances, there is a need for caution in interpreting the results obtained from such algorithms. Specifically, we shall show that the application of statistical methods to problems of object reconstruction, in situations where only the modulus of the object Fourier transform is known, could lead to wholly false conclusions. Indeed, we shall primarily be concerned here with situations for which there is no ‘correct’ solution. In such situations it is pointless to speak of ‘safe’ object reconstruction algorithms. The important point here is that the user of a statistically based ‘object reconstruction algorithm’ may be totally ignorant of whether or not he is working in this régime.

scholarly journals A New Statistical Reconstruction Method for the Computed Tomography Using an X-Ray Tube with Flying Focal Spot

2021 ◽  
Vol 11 (4) ◽  
pp. 271-286
Author(s):  
Robert Cierniak ◽  
Piotr Pluta ◽  
Marek Waligóra ◽  
Zdzisław Szymański ◽  
Konrad Grzanek ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Focal Spot ◽  
Reconstruction Method ◽  
Reconstruction Procedure ◽  
X Ray ◽  
Statistical Reconstruction ◽  
Reconstruction Methods ◽  
Ct Scanners ◽  
The Impact

Abstract This paper presents a new image reconstruction method for spiral cone- beam tomography scanners in which an X-ray tube with a flying focal spot is used. The method is based on principles related to the statistical model-based iterative reconstruction (MBIR) methodology. The proposed approach is a continuous-to-continuous data model approach, and the forward model is formulated as a shift-invariant system. This allows for avoiding a nutating reconstruction-based approach, e.g. the advanced single slice rebinning methodology (ASSR) that is usually applied in computed tomography (CT) scanners with X-ray tubes with a flying focal spot. In turn, the proposed approach allows for significantly accelerating the reconstruction processing and, generally, for greatly simplifying the entire reconstruction procedure. Additionally, it improves the quality of the reconstructed images in comparison to the traditional algorithms, as confirmed by extensive simulations. It is worth noting that the main purpose of introducing statistical reconstruction methods to medical CT scanners is the reduction of the impact of measurement noise on the quality of tomography images and, consequently, the dose reduction of X-ray radiation absorbed by a patient. A series of computer simulations followed by doctor’s assessments have been performed, which indicate how great a reduction of the absorbed dose can be achieved using the reconstruction approach presented here.

Shape Reconstruction of Liquid Ligaments and Droplets Model via Multi-View Digital Inline Holography

2021 ◽  
Author(s):  
Weixiao Shang ◽  
Mateo Gomez ◽  
Terrence R. Meyer ◽  
Jun Chen
Keyword(s):  
Cross Section ◽  
Test Model ◽  
Phase Information ◽  
Post Process ◽  
Reconstruction Methods ◽  
Hologram Plane ◽  
Plane Direction ◽  
The Cross ◽  
The One ◽  
Reconstructed Model

Abstract Digital inline holography (DIH), as a three-dimensional (3D) measurement technique, is widely used in characterizations of the particles, droplets or bubbles under different multi-phase flow circumstances. By analyzing the phase information carried by the interference pattern, the reconstruction of shape and the location of a test target is then achieved. However, such reconstruction mechanism produces different levels of uncertainty between the in-plane (the plane parallel to the hologram plane) direction and out-of-plane (the plane normal to the hologram plane) direction, and the uncertainty of the latter is larger than the former. Also, the reconstruction algorithm fails when the interference patterns of some sections of the target are overlapped on the hologram since the overlapped patterns are merged into a pure shadow which doesn’t carry any phase information. This paper tested a method, the Multi-view Digital Inline Holography (MvDIH), that combines the holograms recorded from multiple views to overcome the addressed defects of the single view DIH. This technique uses the similar setup as the DIH but applies a different post-process method to implement the reconstruction. As the DIH is applied to each view, one can not only acquire the cross-section of the target in the hologram plane but also the outline of such cross-section in the space. Then, two reconstruction methods with different ideologies are developed as, the one based on the outline and the one based on the cross-section. A post-process algorithm is developed to realize these two reconstruction methods with the holograms recorded from different views. To evaluate the performance of the Multi-view DIH, a test model which imitates the droplet and liquid ligament structure is 3D printed and measured by the proposed method. The results demonstrate that, with only three view, both method provides limited reconstruction result. When comparing to the true test model, for the outline based method, some parts of the reconstructed model are missing and some details are merged into one piece with simple geometry. Yet, for the cross-section based method, the reconstructed model contains redundant parts which also make such result unsatisfied. As the used holograms are increased to six views, the reconstructed result for cross-section based method is approaching to the true model, but still some sections are reconstructed with certain level of ambiguity.

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.

Electron holography of catalysts

1995 ◽  
Vol 53 ◽  
pp. 416-417
Author(s):  
A. K. Datye ◽  
D. S. Kalakkad ◽  
L. F. Allard ◽  
E. Völkl
Keyword(s):  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Scale ◽  
Nano Particles ◽  
Phase Image ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Phase Information ◽  
Particle Structure

The active phase in heterogeneous catalysts consists of nanometer-sized metal or oxide particles dispersed within the tortuous pore structure of a high surface area matrix. Such catalysts are extensively used for controlling emissions from automobile exhausts or in industrial processes such as the refining of crude oil to produce gasoline. The morphology of these nano-particles is of great interest to catalytic chemists since it affects the activity and selectivity for a class of reactions known as structure-sensitive reactions. In this paper, we describe some of the challenges in the study of heterogeneous catalysts, and provide examples of how electron holography can help in extracting details of particle structure and morphology on an atomic scale.Conventional high-resolution TEM imaging methods permit the image intensity to be recorded, but the phase information in the complex image wave is lost. However, it is the phase information which is sensitive at the atomic scale to changes in specimen thickness and composition, and thus analysis of the phase image can yield important information on morphological details at the nanometer level.

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.

Structural Studies on the Eukaryotic Ribosome

1990 ◽  
Vol 48 (1) ◽  
pp. 256-257
Author(s):  
Adriana Verschoor ◽  
Ronald Milligan ◽  
Suman Srivastava ◽  
Joachim Frank
Keyword(s):  
Chick Embryo ◽  
3D Reconstruction ◽  
Single Particle ◽  
Mass Density ◽  
Particle Surface ◽  
Uranyl Acetate ◽  
Electron Microscopic ◽  
Eukaryotic Ribosome ◽  
Negative Stain ◽  
Reconstruction Methods

We have studied the eukaryotic ribosome from two vertebrate species (rabbit reticulocyte and chick embryo ribosomes) in several different electron microscopic preparations (Fig. 1a-d), and we have applied image processing methods to two of the types of images. Reticulocyte ribosomes were examined in both negative stain (0.5% uranyl acetate, in a double-carbon preparation) and frozen hydrated preparation as single-particle specimens. In addition, chick embryo ribosomes in tetrameric and crystalline assemblies in frozen hydrated preparation have been examined. 2D averaging, multivariate statistical analysis, and classification methods have been applied to the negatively stained single-particle micrographs and the frozen hydrated tetramer micrographs to obtain statistically well defined projection images of the ribosome (Fig. 2a,c). 3D reconstruction methods, the random conical reconstruction scheme and weighted back projection, were applied to the negative-stain data, and several closely related reconstructions were obtained. The principal 3D reconstruction (Fig. 2b), which has a resolution of 3.7 nm according to the differential phase residual criterion, can be compared to the images of individual ribosomes in a 2D tetramer average (Fig. 2c) at a similar resolution, and a good agreement of the general morphology and of many of the characteristic features is seen.Both data sets show the ribosome in roughly the same ’view’ or orientation, with respect to the adsorptive surface in the electron microscopic preparation, as judged by the agreement in both the projected form and the distribution of characteristic density features. The negative-stain reconstruction reveals details of the ribosome morphology; the 2D frozen-hydrated average provides projection information on the native mass-density distribution within the structure. The 40S subunit appears to have an elongate core of higher density, while the 60S subunit shows a more complex pattern of dense features, comprising a rather globular core, locally extending close to the particle surface.

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