Monochromatic X-ray microscopy in the water window with a compact laser system

It is a dream of biologist to observe the intact structure of a biological specimen at high resolution without any artifacts. The development of high resolution x-ray microscopy is a new technique well suited to this purpose. The advantages of x-ray microscopy are seen to be: (i) the contrast can be provided by its components, thereby avoiding possible artifacts caused by the staining and fixation of specimens; (ii) x-ray microscopy is capable of observing thicker specimens (up to a few (μm)than electron microscopy with less damage; (iii) the actual location of the element can be visualizedwhen the proper x-ray wavelength is chosen. (iv) three-dimensional observation may be possible with asingle exposure of x rays. X-ray contact microscopy is presendy the most suitable method by which to evaluate these advantages.It is generally accepted that the highest contrast in x-ray images of in-vitro biological specimens will be obtained with radiation have a wavelength in the so-called “water window”, (2.3-4.4 nm). Both laser plasmas and synchrotrons are bright source of radiation in this region.

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Hard X-ray polarizer to enable simultaneous three-dimensional nanoscale imaging of magnetic structure and lattice strain

Journal of Synchrotron Radiation ◽

10.1107/s1600577516009632 ◽

2016 ◽

Vol 23 (5) ◽

pp. 1210-1215 ◽

Cited By ~ 3

Author(s):

Jonathan Logan ◽

Ross Harder ◽

Luxi Li ◽

Daniel Haskel ◽

Pice Chen ◽

...

Keyword(s):

Magnetic Circular Dichroism ◽

Three Dimensional ◽

Control Sample ◽

Magnetic Ordering ◽

X Rays ◽

Diffractive Imaging ◽

X Ray ◽

Coherent Diffractive Imaging ◽

Diffraction Patterns ◽

A New Technique

Recent progress in the development of dichroic Bragg coherent diffractive imaging, a new technique for simultaneous three-dimensional imaging of strain and magnetization at the nanoscale, is reported. This progress includes the installation of a diamond X-ray phase retarder at beamline 34-ID-C of the Advanced Photon Source. The performance of the phase retarder for tuning X-ray polarization is demonstrated with temperature-dependent X-ray magnetic circular dichroism measurements on a gadolinium foil in transmission and on a Gd5Si2Ge2crystal in diffraction geometry with a partially coherent, focused X-ray beam. Feasibility tests for dichroic Bragg coherent diffractive imaging are presented. These tests include (1) using conventional Bragg coherent diffractive imaging to determine whether the phase retarder introduces aberrations using a nonmagnetic gold nanocrystal as a control sample, and (2) collecting coherent diffraction patterns of a magnetic Gd5Si2Ge2nanocrystal with left- and right-circularly polarized X-rays. Future applications of dichroic Bragg coherent diffractive imaging for the correlation of strain and lattice defects with magnetic ordering and inhomogeneities are considered.

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Correction for patient sway in radiographic biplanar imaging for three-dimensional reconstruction of the spine: in vitro study of a new method

Acta Radiologica ◽

10.1080/02841850903036272 ◽

2009 ◽

Vol 50 (7) ◽

pp. 781-790 ◽

Cited By ~ 6

Author(s):

J. Legaye ◽

P. Saunier ◽

R. Dumas ◽

C. Vallee

Keyword(s):

3D Reconstruction ◽

Three Dimensional ◽

In Vitro Study ◽

X Rays ◽

3D Reconstructions ◽

X Ray ◽

Scoliosis Research Society ◽

The Impact ◽

Corrective Method

Background: Three-dimensional (3D) reconstructions of the spine in the upright position are classically obtained using two-dimensional, non-simultaneous radiographic imaging. However, a subject's sway between exposures induces inaccuracy in the 3D reconstructions. Purpose: To evaluate the impact of patient sway between successive radiographic exposures, and to test if 3D reconstruction accuracy can be improved by a corrective method with simultaneous Moiré–X-ray imaging. Material and Methods: Using a calibrated deformable phantom perceptible by both techniques (Moiré and X-ray), the 3D positional and rotational vertebral data from 3D reconstructions with and without the corrective procedure were compared to the corresponding data of computed tomography (CT) scans, considered as a reference. All were expressed in the global axis system, as defined by the Scoliosis Research Society. Results: When a sagittal sway of 10° occurred between successive biplanar X-rays, the accuracy of the 3D reconstruction without correction was 8.8 mm for the anteroposterior vertebral locations and 6.4° for the sagittal orientations. When the corrective method was applied, the accuracy was improved to 1.3 mm and 1.5°, respectively. Conclusion: 3D accuracy improved significantly by using the corrective method, whatever the subject's sway. This technique is reliable for clinical appraisal of the spine, if the subject's sway does not exceed 10°. For greater sway, improvement persists, but a risk of lack of accuracy exists.

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X-ray Gabor holography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100139433 ◽

1995 ◽

Vol 53 ◽

pp. 612-613

Author(s):

Steve Lindaas ◽

Chris Jacobsen ◽

Alex Kalinovsky ◽

Malcolm Howells

Keyword(s):

Surface Relief ◽

Biological Imaging ◽

Specimen Preparation ◽

X Rays ◽

X Ray ◽

Water Window ◽

Biological Objects ◽

Transmission Imaging ◽

Atomic Force ◽

Electron Microscopes

Soft x-ray microscopy offers an approach to transmission imaging of wet, micron-thick biological objects at a resolution superior to that of optical microscopes and with less specimen preparation/manipulation than electron microscopes. Gabor holography has unique characteristics which make it particularly well suited for certain investigations: it requires no prefocussing, it is compatible with flash x-ray sources, and it is able to use the whole footprint of multimode sources. Our method serves to refine this technique in anticipation of the development of suitable flash sources (such as x-ray lasers) and to develop cryo capabilities with which to reduce specimen damage. Our primary emphasis has been on biological imaging so we use x-rays in the water window (between the Oxygen-K and Carbon-K absorption edges) with which we record holograms in vacuum or in air.The hologram is recorded on a high resolution recording medium; our work employs the photoresist poly(methylmethacrylate) (PMMA). Following resist “development” (solvent etching), a surface relief pattern is produced which an atomic force microscope is aptly suited to image.

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Is Micro X-ray Computer Tomography a Suitable Non-Destructive Method for the Characterisation of Dental Materials?

Polymers ◽

10.3390/polym13081271 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1271

Author(s):

Andreas Koenig ◽

Leonie Schmohl ◽

Johannes Scheffler ◽

Florian Fuchs ◽

Michaela Schulz-Siegmund ◽

...

Keyword(s):

Flexural Strength ◽

Computer Tomography ◽

Mechanical Performance ◽

Dental Materials ◽

Three Dimensional ◽

X Rays ◽

Scanning Calorimetry ◽

X Ray ◽

Multiple Measurements ◽

High Doses

The aim of the study was to investigate the effect of X-rays used in micro X-ray computer tomography (µXCT) on the mechanical performance and microstructure of a variety of dental materials. Standardised bending beams (2 × 2 × 25 mm3) were forwarded to irradiation with an industrial tomograph. Using three-dimensional datasets, the porosity of the materials was quantified and flexural strength was investigated prior to and after irradiation. The thermal properties of irradiated and unirradiated materials were analysed and compared by means of differential scanning calorimetry (DSC). Single µXCT measurements led to a significant decrease in flexural strength of polycarbonate with acrylnitril-butadien-styrol (PC-ABS). No significant influence in flexural strength was identified for resin-based composites (RBCs), poly(methyl methacrylate) (PMMA), and zinc phosphate cement (HAR) after a single irradiation by measurement. However, DSC results suggest that changes in the microstructure of PMMA are possible with increasing radiation doses (multiple measurements, longer measurements, higher output power from the X-ray tube). In summary, it must be assumed that X-ray radiation during µXCT measurement at high doses can lead to changes in the structure and properties of certain polymers.

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Optimization of X-ray Investigations in Dentistry Using Optical Coherence Tomography

Sensors ◽

10.3390/s21134554 ◽

2021 ◽

Vol 21 (13) ◽

pp. 4554

Author(s):

Ralph-Alexandru Erdelyi ◽

Virgil-Florin Duma ◽

Cosmin Sinescu ◽

George Mihai Dobre ◽

Adrian Bradu ◽

...

Keyword(s):

Optical Coherence Tomography ◽

Radiation Dose ◽

Imaging Techniques ◽

Image Resolution ◽

Optical Coherence ◽

X Rays ◽

High Quality ◽

X Ray

The most common imaging technique for dental diagnoses and treatment monitoring is X-ray imaging, which evolved from the first intraoral radiographs to high-quality three-dimensional (3D) Cone Beam Computed Tomography (CBCT). Other imaging techniques have shown potential, such as Optical Coherence Tomography (OCT). We have recently reported on the boundaries of these two types of techniques, regarding. the dental fields where each one is more appropriate or where they should be both used. The aim of the present study is to explore the unique capabilities of the OCT technique to optimize X-ray units imaging (i.e., in terms of image resolution, radiation dose, or contrast). Two types of commercially available and widely used X-ray units are considered. To adjust their parameters, a protocol is developed to employ OCT images of dental conditions that are documented on high (i.e., less than 10 μm) resolution OCT images (both B-scans/cross sections and 3D reconstructions) but are hardly identified on the 200 to 75 μm resolution panoramic or CBCT radiographs. The optimized calibration of the X-ray unit includes choosing appropriate values for the anode voltage and current intensity of the X-ray tube, as well as the patient’s positioning, in order to reach the highest possible X-rays resolution at a radiation dose that is safe for the patient. The optimization protocol is developed in vitro on OCT images of extracted teeth and is further applied in vivo for each type of dental investigation. Optimized radiographic results are compared with un-optimized previously performed radiographs. Also, we show that OCT can permit a rigorous comparison between two (types of) X-ray units. In conclusion, high-quality dental images are possible using low radiation doses if an optimized protocol, developed using OCT, is applied for each type of dental investigation. Also, there are situations when the X-ray technology has drawbacks for dental diagnosis or treatment assessment. In such situations, OCT proves capable to provide qualitative images.

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Visualizing Fluid Flows With X-Rays

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2007-37023 ◽

2007 ◽

Cited By ~ 4

Author(s):

Theodore J. Heindel ◽

Terrence C. Jensen ◽

Joseph N. Gray

Keyword(s):

Computed Tomography ◽

Flow Visualization ◽

Three Dimensional ◽

Fluid Flows ◽

X Rays ◽

Radiographic Images ◽

Optical Access ◽

X Ray ◽

X Ray Computed ◽

Density Map

There are several methods available to visualize fluid flows when one has optical access. However, when optical access is limited to near the boundaries or not available at all, alternative visualization methods are required. This paper will describe flow visualization using an X-ray system that is capable of digital X-ray radiography, digital X-ray stereography, and digital X-ray computed tomography (CT). The unique X-ray flow visualization facility will be briefly described, and then flow visualization of various systems will be shown. Radiographs provide a two-dimensional density map of a three dimensional process or object. Radiographic images of various multiphase flows will be presented. When two X-ray sources and detectors simultaneously acquire images of the same process or object from different orientations, stereographic imaging can be completed; this type of imaging will be demonstrated by trickling water through packed columns and by absorbing water in a porous medium. Finally, local time-averaged phase distributions can be determined from X-ray computed tomography (CT) imaging, and this will be shown by comparing CT images from two different gas-liquid sparged columns.

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Recent Developments In Monochromatic Microprobe X-Ray Fluorescence (MMXRF)

Microscopy and Microanalysis ◽

10.1017/s1431927600022017 ◽

1998 ◽

Vol 4 (S2) ◽

pp. 378-379

Author(s):

Z. W. Chen ◽

D. B. Wittry

Keyword(s):

Materials Science ◽

High Vacuum ◽

Three Dimensional ◽

High Sensitivity ◽

X Rays ◽

Fluorescence Excitation ◽

X Ray ◽

Quantitative Microanalysis ◽

Recent Developments ◽

Fifth Order

A monochromatic x-ray microprobe based on a laboratory source has recently been developed in our laboratory and used for fluorescence excitation. This technique provides high sensitivity (ppm to ppb), nondestructive, quantitative microanalysis with minimum sample preparation and does not require a high vacuum specimen chamber. It is expected that this technique (MMXRF) will have important applications in materials science, geological sciences and biological science.Three-dimensional focusing of x-rays can be obtained by using diffraction from doubly curved crystals. In our MMXRF setup, a small x-ray source was produced by the bombardment of a selected target with a focused electron beam and a toroidal mica diffractor with Johann pointfocusing geometry was used to focus characteristic x-rays from the source. In the previous work ∼ 108 photons/s were obtained in a Cu Kα probe of 75 μm × 43 μm in the specimen plane using the fifth order reflection of the (002) planes of mica.

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Three-dimensional crystallization of membrane proteins

Quarterly Reviews of Biophysics ◽

10.1017/s0033583500004625 ◽

1988 ◽

Vol 21 (4) ◽

pp. 429-477 ◽

Cited By ~ 156

Author(s):

W. Kühlbrandt

Keyword(s):

High Resolution ◽

Membrane Proteins ◽

Membrane Protein ◽

Protein Complexes ◽

Three Dimensional ◽

Biological Macromolecules ◽

X Ray ◽

X Ray Crystallography ◽

Membrane Protein Complexes ◽

Essential Prerequisite

As recently as 10 years ago, the prospect of solving the structure of any membrane protein by X-ray crystallography seemed remote. Since then, the threedimensional (3-D) structures of two membrane protein complexes, the bacterial photosynthetic reaction centres of Rhodopseudomonas viridis (Deisenhofer et al. 1984, 1985) and of Rhodobacter sphaeroides (Allen et al. 1986, 1987 a, 6; Chang et al. 1986) have been determined at high resolution. This astonishing progress would not have been possible without the pioneering work of Michel and Garavito who first succeeded in growing 3-D crystals of the membrane proteins bacteriorhodopsin (Michel & Oesterhelt, 1980) and matrix porin (Garavito & Rosenbusch, 1980). X-ray crystallography is still the only routine method for determining the 3-D structures of biological macromolecules at high resolution and well-ordered 3-D crystals of sufficient size are the essential prerequisite.

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