Tensor Tomography of Dark Field Scatter using X-ray Interferometry with Bi-prisms

Simulation study towards quantitative X-ray and neutron tensor tomography regarding the validity of linear approximations of dark-field anisotropy

Scientific Reports ◽

10.1038/s41598-021-97389-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jonas Graetz

Keyword(s):

Simulation Study ◽

Full Range ◽

Dark Field ◽

Orientation Dependence ◽

Field Tensor ◽

Axis Orientation ◽

X Ray ◽

Tensor Tomography ◽

Order Of Magnitude ◽

Linear Contrast

AbstractTensor tomography is fundamentally based on the assumption of a both anisotropic and linear contrast mechanism. While the X-ray or neutron dark-field contrast obtained with Talbot(-Lau) interferometers features the required anisotropy, a preceding detailed study of dark-field signal origination however found its specific orientation dependence to be a non-linear function of the underlying anisotropic mass distribution and its orientation, especially challenging the common assumption that dark-field signals are describable by a function over the unit sphere. Here, two approximative linear tensor models with reduced orientation dependence are investigated in a simulation study with regard to their applicability to grating based X-ray or neutron dark-field tensor tomography. By systematically simulating and reconstructing a large sample of isolated volume elements covering the full range of feasible anisotropies and orientations, direct correspondences are drawn between the respective tensors characterizing the physically based dark-field model used for signal synthesization and the mathematically motivated simplified models used for reconstruction. The anisotropy of freely rotating volume elements is thereby confirmed to be, for practical reconstruction purposes, approximable both as a function of the optical axis’ orientation or as a function of the interferometer’s grating orientation. The eigenvalues of the surrogate models’ tensors are found to exhibit fuzzy, yet almost linear relations to those of the synthesization model. Dominant orientations are found to be recoverable with a margin of error on the order of magnitude of 1$$^{\circ }$$ ∘ . Although the input data must adequately address the full orientation dependence of dark-field anisotropy, the present results clearly support the general feasibility of quantitative X-ray dark-field tensor tomography within an inherent yet acceptable statistical margin of uncertainty.

Download Full-text

Nanostructure-specific X-ray tomography reveals myelin levels, integrity and axon orientations in mouse and human nervous tissue

Nature Communications ◽

10.1038/s41467-021-22719-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Marios Georgiadis ◽

Aileen Schroeter ◽

Zirui Gao ◽

Manuel Guizar-Sicairos ◽

Marianne Liebi ◽

...

Keyword(s):

Mouse Brain ◽

Nervous Tissue ◽

Signal Transmission ◽

X Ray ◽

Tensor Tomography ◽

Quantitative Studies ◽

X Ray Scattering ◽

Imaging Approach ◽

Non Destructive ◽

Mri Measurements

AbstractMyelin insulates neuronal axons and enables fast signal transmission, constituting a key component of brain development, aging and disease. Yet, myelin-specific imaging of macroscopic samples remains a challenge. Here, we exploit myelin’s nanostructural periodicity, and use small-angle X-ray scattering tensor tomography (SAXS-TT) to simultaneously quantify myelin levels, nanostructural integrity and axon orientations in nervous tissue. Proof-of-principle is demonstrated in whole mouse brain, mouse spinal cord and human white and gray matter samples. Outcomes are validated by 2D/3D histology and compared to MRI measurements sensitive to myelin and axon orientations. Specificity to nanostructure is exemplified by concomitantly imaging different myelin types with distinct periodicities. Finally, we illustrate the method’s sensitivity towards myelin-related diseases by quantifying myelin alterations in dysmyelinated mouse brain. This non-destructive, stain-free molecular imaging approach enables quantitative studies of myelination within and across samples during development, aging, disease and treatment, and is applicable to other ordered biomolecules or nanostructures.

Download Full-text

Correlation of image quality parameters with tube voltage in X-ray dark-field chest radiography: a phantom study

Scientific Reports ◽

10.1038/s41598-021-93716-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Andreas P. Sauter ◽

Jana Andrejewski ◽

Manuela Frank ◽

Konstantin Willer ◽

Julia Herzen ◽

...

Keyword(s):

Image Quality ◽

Imaging Modality ◽

Signal Strength ◽

Dark Field ◽

Tube Voltage ◽

X Ray ◽

Dose Area Product ◽

Dark Field Imaging ◽

Field Imaging

AbstractGrating-based X-ray dark-field imaging is a novel imaging modality with enormous technical progress during the last years. It enables the detection of microstructure impairment as in the healthy lung a strong dark-field signal is present due to the high number of air-tissue interfaces. Using the experience from setups for animal imaging, first studies with a human cadaver could be performed recently. Subsequently, the first dark-field scanner for in-vivo chest imaging of humans was developed. In the current study, the optimal tube voltage for dark-field radiography of the thorax in this setup was examined using an anthropomorphic chest phantom. Tube voltages of 50–125 kVp were used while maintaining a constant dose-area-product. The resulting dark-field and attenuation radiographs were evaluated in a reader study as well as objectively in terms of contrast-to-noise ratio and signal strength. We found that the optimum tube voltage for dark-field imaging is 70 kVp as here the most favorable combination of image quality, signal strength, and sharpness is present. At this voltage, a high image quality was perceived in the reader study also for attenuation radiographs, which should be sufficient for routine imaging. The results of this study are fundamental for upcoming patient studies with living humans.

Download Full-text

Dark-Field X-Ray Microscopy of Immunogold-Labeled Cells

Microscopy and Microanalysis ◽

10.1017/s1431927696210530 ◽

1996 ◽

Vol 2 (2) ◽

pp. 53-62 ◽

Cited By ~ 3

Author(s):

Henry N. Chapman ◽

Jenny Fu ◽

Chris Jacobsen ◽

Shawn Williams

Keyword(s):

Colloidal Gold ◽

Dark Field Image ◽

Dark Field ◽

X Rays ◽

X Ray ◽

Scanning Transmission ◽

A Cell ◽

Specific Antigens ◽

Genetic Sequences ◽

Novel Method

The methods of immunolabeling make visible the presence of specific antigens, proteins, genetic sequences, or functions of a cell. In this paper we present examples of imaging immunolabels in a scanning transmission x-ray microscope using the novel method of dark-field contrast. Colloidal gold, or silver-enhanced colloidal gold, is used as a label, which strongly scatters x-rays. This leads to a high-contrast dark-field image of the label and reduced radiation dose to the specimen. The x-ray images are compared with electron micrographs of the same labeled, unsectioned, whole cell. It is verified that the dark-field x-ray signal is primarily due to the label and the bright-field x-ray signal, showing absorption due to carbon, is largely unaffected by the label. The label can be well visualized even when it is embedded in or laying behind dense material, such as the cell nucleus. The resolution of the images is measured to be 60 nm, without the need for computer processing. This figure includes the x-ray microscope resolution and the accuracy of the label positioning. The technique should be particularly useful for the study of relatively thick (up to 10 μm), wet, or frozen hydrated specimens.

Download Full-text