EIGER2 hybrid-photon-counting X-ray detectors for advanced synchrotron diffraction experiments.

The ability to utilize a hybrid-photon-counting detector to its full potential can significantly influence data quality, data collection speed, as well as development of elaborate data acquisition schemes. This paper facilitates the optimal use of EIGER2 detectors by providing theory and practical advice on (i) the relation between detector design, technical specifications and operating modes, (ii) the use of corrections and calibrations, and (iii) new acquisition features: a double-gating mode, 8-bit readout mode for increasing temporal resolution, and lines region-of-interest readout mode for frame rates up to 98 kHz. Examples of the implementation and application of EIGER2 at several synchrotron sources (ESRF, PETRA III/DESY, ELETTRA, AS/ANSTO) are presented: high accuracy of high-throughput data in serial crystallography using hard X-rays; suppressing higher harmonics of undulator radiation, improving peak shapes, increasing data collection speed in powder X-ray diffraction; faster ptychography scans; and cleaner and faster pump-and-probe experiments.

A tilted grating interferometer for full vector field differential x-ray phase contrast tomography.

We report on a setup for differential x-ray phase-contrast imaging and tomography, that measures the full 2D phase-gradient information. The setup uses a simple one-dimensional x-ray grating interferometer, in which the grating structures of the interferometer are oriented at a tilt angle with respect to the sample rotation axis. In such a configuration, the differential phase images from opposing tomography projections can be combined to yield both components of the gradient vector.

X-ray grating interferometer for materials-science imaging at a low-coherent wiggler source.

X-ray phase-contrast radiography and tomography enable to increase contrast for weakly absorbing materials. Recently, x-ray grating interferometers were developed that extend the possibility of phase-contrast imaging from highly brilliant radiation sources like third-generation synchrotron sources to non-coherent conventional x-ray tube sources. Here, we present the first installation of a three grating x-ray interferometer at a low-coherence wiggler source at the beamline W2 (HARWI II) operated by the Helmholtz-Zentrum Geesthacht at the second-generation synchrotron storage ring DORIS (DESY, Hamburg, Germany).

Beam hardening effects in grating-based x-ray phase-contrast imaging.

Purpose: In this work, the authors investigate how beam hardening affects the image formation in x-ray phase-contrast imaging and consecutively develop a correction algorithm based on the results of the analysis.

Methods: The authors' approach utilizes a recently developed x-ray imaging technique using a grating interferometer capable of visualizing the differential phase shift of a wave front traversing an object. An analytical description of beam hardening is given, highlighting differences between attenuation and phase-contrast imaging.

Two-dimensional x-ray grating interferometer.

We report on the design and experimental realization of a 2D x-ray grating interferometer. We describe how this interferometer has been practically implemented, discuss its performance, and present multidirectional scattering (dark-field) maps and quantitative phase images that have been retrieved using this device.

Toward clinical X-ray phase-contrast CT: demonstration of enhanced soft-tissue contrast in human specimen.

Objectives: X-ray computed tomography (CT) using phase contrast can provide images with greatly enhanced soft-tissue contrast in comparison to conventional attenuation-based CT. We report on the first scan of a human specimen recorded with a phase-contrast CT system based on an x-ray grating interferometer and a conventional x-ray tube source. Feasibility and potential applications of preclinical and clinical phase-contrast CT are discussed.

Directional x-ray dark-field imaging.

We introduce a novel x-ray imaging approach that yields information about the local texture of structures smaller than the image pixel resolution inside an object. The approach is based on a recently developed x-ray dark-field imaging technique, using scattering from sub-micron structures in the sample. We show that the method can be used to determine the local angle and degree of orientation of bone, and fibers in a leaf.

Advanced contrast modalities for X-ray radiology: Phase-contrast and dark-field imaging using a grating interferometer.

Here we review our recent progress in the field of X-ray dark-field and phase-contrast imaging using a grating interferometer. We describe the basic imaging principles of grating-based phase-contrast and dark-field radiography and present some exemplary results obtained for simple test objects and biological specimens. Furthermore, we discuss how phase-contrast and dark-field radiography can be combined with the concept of computed tomography, and yield highly detailed three-dimensional insights into biomedical sample.

Quantitative phase-contrast tomography of a liquid phantom using a conventional x-ray tube source.

Over the last few years, differential phase-contrast x-ray computed tomography (PC-CT) using a hard x-ray grating interferometer and polychromatic x-ray tube sources has been developed. The method allows for simultaneous determination of the attenuation coefficient and the refractive index decrement distribution inside an object in three dimensions. Here we report experimental results of our investigation on the quantitativeness and accuracy of this method.

Phase-contrast imaging and tomography at 60 keV using a conventional x-ray tube source.

Phase-contrast imaging at laboratory-based x-ray sources using grating interferometers has been developed over the last few years for x-ray energies of up to 28 keV. Here, we show first phase-contrast projection and tomographic images recorded at significantly higher x-ray energies, produced by an x-ray tube source operated at 100 kV acceleration voltage. We find our measured tomographic phase images in good agreement with tabulated data.

Automated determination of the center of rotation in tomography data.

Tomographic reconstruction requires precise knowledge of the position of the center of rotation in the sinogram data; otherwise, artifacts are introduced into the reconstruction. In parallel-beam microtomography, where resolution in the 1 microm range is reached, the center of rotation is often only known with insufficient accuracy. We present three image metrics for the scoring of tomographic reconstructions and an iterative procedure for the determination of the position of the optimum center of rotation.

Application of synchrotron-radiation-based computer microtomography (SRICT) to selected biominerals: embryonic snails, statoliths of medusae, and human teeth.

Synchrotron-radiation-based computer microtomography (SRmicroCT) was applied to three biomineralised objects First, embryonic snails of the freshwater snail Biomphalaria glabrata, second, rhopalia (complex sense organs) of the medusa Aurelia aurita, and third, human teeth. The high absorption contrast between the soft tissue and mineralised tissues, i.e.

Calcium sulfate hemihydrate is the inorganic mineral in statoliths of Scyphozoan medusae (Cnidaria).

Scyphomedusae use inorganic crystals (statoliths) for gravity sensing. The organs which contain the statoliths are called rhopalia. Rhopalia of five different species of the three different orders of the class Scyphozoa were studied with high-end solid-state chemical methods to elucidate the crystallographic nature of the biomineral: synchrotron powder diffraction, synchrotron single-crystal diffraction, synchrotron microtomography, scanning electron microscopy, and energy dispersive X-ray spectroscopy.