X-ray Phase Contrast Research Articles

The Study of the Caudal Vertebrae of Thick-Toed Geckos after a Prolonged Space Flight by X-ray Phase-Contrast Micro-CT.

The proximal caudal vertebrae and notochord in thick-toed geckos (TG) (Chondrodactylus turneri, Gray, 1864) were investigated after a 30-day space flight onboard the biosatellite Bion-M1. This region has not been explored in previous studies. Our research focused on finding sites most affected by demineralization caused by microgravity (G0). We used X-ray phase-contrast tomography to study TG samples without invasive prior preparation to clarify our previous findings on the resistance of TG's bones to demineralization in G0. The results of the present study confirmed that geckos are capable of preserving bone mass after flight, as neither cortical nor trabecular bone volume fraction showed statistically significant changes after flight. On the other hand, we observed a clear decrease in the mineralization of the notochordal septum and a substantial rise in intercentrum volume following the flight. To monitor TG's mineral metabolism in G0, we propose to measure the volume of mineralized tissue in the notochordal septum. This technique holds promise as a sensitive approach to track the demineralization process in G0, given that the volume of calcification within the septum is limited, making it easy to detect even slight changes in mineral content.

Distribution of corpora amylacea in the human midbrain: using synchrotron radiation phase-contrast microtomography, high-field magnetic resonance imaging, and histology.

Corpora amylacea (CA) are polyglucosan aggregated granules that accumulate in the human body throughout aging. In the cerebrum, CA have been found in proximity to ventricular walls, pial surfaces, and blood vessels. However, studies showing their three-dimensional spatial distribution are sparse. In this study, volumetric images of four human brain stems were obtained with MRI and phase-contrast X-ray microtomography, followed up by Periodic acid Schiff stain for validation. CA appeared as hyperintense spheroid structures with diameters up to 30 μm. An automatic pipeline was developed to segment the CA, and the spatial distribution of over 200,000 individual corpora amylacea could be investigated. A threefold-or higher-density of CA was detected in the dorsomedial column of the periaqueductal gray (860-4,200 CA count/mm3) than in the superior colliculus (150-340 CA count/mm3). We estimated that about 2% of the CA were located in the immediate vicinity of the vessels or in the peri-vascular space. While CA in the ependymal lining of the cerebral aqueduct was rare, the sub-pial tissue of the anterior and posterior midbrain contained several CA. In the sample with the highest CA density, quantitative maps obtained with MRI revealed high R2* values and a diamagnetic shift in a region which spatially coincided with the CA dense region.

A cadaveric breast cancer tissue phantom for phase-contrast X-ray imaging applications.

As mammography X-ray imaging technologies advance and provide elevated contrast in soft tissues, a need has developed for reliable imaging phantoms for use in system design and component calibration. In advanced imaging modalities such as refraction-based methods, it is critical that developed phantoms capture the biological details seen in clinical precancerous and cancerous cases while minimizing artifacts that may be caused due to phantom production. This work presents the fabrication of a breast tissue imaging phantom from cadaveric breast tissue suitable for use in both transmission and refraction-enhanced imaging systems. Human cancer cell tumors were grown orthotopically in nude athymic mice and implanted into the fixed tissue while maintaining the native tumor/adipose tissue interface. The resulting human-murine tissue hybrid phantom was mounted on a clear acrylic housing for absorption and refraction X-ray imaging. Digital breast tomosynthesis was also performed. Both attenuation-based imaging and refraction-based imaging of the phantom are presented to confirm the suitability of this phantom's use in both imaging modalities.

Observation of Impact Induced Failure in Slotted HMX Crystals Using X-Ray Phase Contrast Imaging

Observation of Impact Induced Failure in Slotted HMX Crystals Using X-Ray Phase Contrast Imaging

In situ damage characterization of CFRP under compression using high-speed optical, infrared and synchrotron X-ray phase-contrast imaging

The strain rate dependency and failure modes of carbon fiber reinforced plastic (CFRP) laminate were investigated under out-of-plane compressive loading. Simultaneous high-speed optical and infrared imaging were used to measure full-field deformation and temperature in the dynamically loaded specimens. The damage initiation and propagation inside the CFRP laminates at high strain rates were characterized using in-situ ultra-fast synchrotron X-ray phase contrast imaging (XPCI). The visually observed damage onset occurs at the strain value of 4.2 ± 0.6% as a transverse shear fracture at the free edge of specimens. The local temperature increases significantly to 185 °C due to damage initiation at high strain rates, while at low strain rates the temperature rise occurs after the final shear band forms. The XPCI and post-failure analysis provide an integrated perspective on the formation of a diagonal shear crack and disintegration of the specimen into two pieces with the fracture of plies in the in-plane transverse direction. Scanning electron microscopic (SEM) study was integrated with XPCI results to append the time scale for the post-mortem failure pattern as well as the length scale for microcracks and filament-level failure.

X-ray phase contrast imaging of endomyocardial biopsy samples preserved in formalin and embedded in paraffin – a comparison of tissue preparation methods

X-ray phase contrast imaging of endomyocardial biopsy samples preserved in formalin and embedded in paraffin – a comparison of tissue preparation methods

P21-06: Phase-contrast X-ray imaging detects morphological changes in brain of rat exposed to diesel exhaust originated secondary organic aerosol perinatally

P21-06: Phase-contrast X-ray imaging detects morphological changes in brain of rat exposed to diesel exhaust originated secondary organic aerosol perinatally

Tri-directional x-ray phase contrast multimodal imaging using one hexagonal mesh modulator.

Objective. X-ray phase contrast imaging is a promising technique for future clinical diagnostic as it can provide enhanced contrast in soft tissues compared to traditional x-ray attenuation-contrast imaging. However, the strict requirements on the x-ray coherence and the precise alignment of optical elements limit its applications towards clinical use. To solve this problem, mesh-based x-ray phase contrast imaging method with one hexagonal mesh is proposed for easy alignment and better image visualization.Approach. The mesh produces structured illuminations and the detector captures its distortions to reconstruct the absorption, differential phase contrast (DPC) and dark-field (DF) images of the sample. In this work, we fabricated a hexagonal mesh to simultaneously retrieve DPC and DF signals in three different directions with single shot. A phase retrieval algorithm to obtain artifacts-free phase from DPC images with three different directions is put forward and false color dark-field image is also reconstructed with tri-directional images. Mesh-shifting method based on this hexagonal mesh modulator is also proposed to reconstruct images with better image quality at the expense of increased dose.Main results. In numerical simulations, the proposed hexagonal mesh outperforms the traditional square mesh in image evaluation metrics performance and false color visualization with the same radiation dose. The experimental results demonstrate its feasiblity in real imaging systems and its advantages in quantitive imaging and better visualization. The proposed hexagonal mesh is easy to fabricate and can be successfully applied to x-ray source with it spot size up to 300μm.Significance. This work opens new possibilities for quantitative x-ray non-destructive imaging and may also be instructive for research fields such as x-ray structured illumination microscopy (SIM), x-ray spectral imaging and x-ray phase contrast and dark-field computed tomography (CT).

Homogeneous Field Measurement and Simulation Study of Injector Nozzle Internal Flow and Near-Field Spray

The homogeneous field measurement of internal flow and spray of internal combustion engine injector nozzles under high pressure has always been one of the difficulties in experimental research. In this paper, an actual-size aluminum alloy nozzle is designed, and the simultaneous measurement of internal flow and near-field spray is successfully realized with the help of synchrotron radiation X-ray phase contrast imaging technology under an injection pressure of 30~90 MPa. For a 0.25 mm aperture nozzle, different radii of the inlet corner can induce different cavitation layer thicknesses, and the measured flow section shrinkage ratio is 0.70. The flow characteristics in the nozzle are entirely connected to the jet characteristics, indicating a tight correlation between internal flow and jet morphology. Finally, the internal cavitation of the nozzle was studied by the CFD simulation, and the simulation results are in good agreement with the experiment.

Bronchial tree of the human embryo: Examination based on a mammalian model.

The symmetry of the right and left bronchi, proposed in a previous comparative anatomical study as the basic model of the mammalian bronchial tree, was examined to determine if it applied to the embryonic human bronchial tree. Imaging data of 41 human embryo specimens at Carnegie stages (CS) 16-23 (equivalent to 6-8 weeks after fertilization) belonging to the Kyoto collection were obtained using phase-contrast X-ray computed tomography. Three-dimensional bronchial trees were then reconstructed from these images. Bronchi branching from both main bronchi were labeled as dorsal, ventral, medial, or lateral systems based on the branching position with numbering starting cranially. The length from the tracheal bifurcation to the branching point of the labeled bronchus was measured, and the right-to-left ratio of the same labeled bronchus in both lungs was calculated. In both lungs, the human embryonic bronchial tree showed symmetry with an alternating pattern of dorsal and lateral systems up to segmental bronchus B9 as the basic shape, with a more peripheral variation. This pattern is similar to that described in adult human lungs. Bronchial length increased with the CS in all labeled bronchi, whereas the right-to-left ratio was constant at approximately 1.0. The data demonstrated that the prototype of the human adult bronchial branching structure is formed and maintained in the embryonic stage. The morphology and branching position of all lobar bronchi and B6, B8, B9, and the subsegmental bronchus of B10 may be genetically determined. On the other hand, no common structures between individual embryos were found in the peripheral branches after the subsegmental bronchus of B10, suggesting that branch formation in this region is influenced more by environmental factors than by genetic factors.

Sequence2Self: Self-supervised image sequence denoising of pixel-level spray breakup morphology

Optical imaging of fast and transient phenomena such as the turbulent breakup of liquid sprays exhibit low signal-to-noise ratios due to the limited illumination intensity relative to the short exposure time. Image denoising is required to facilitate physical studies over these data but is challenging due to the absence of clean ground-truths and the stringency of the denoising task (e.g., strong and complex noise, limited resolution, preserving physical fidelity), preventing supervised and existing un-/self-supervised deep learning methods. To this end, Sequence2Self (Seq2S) is proposed, an extension of Self2Self (S2S) to image sequences that leverages both the signal’s spatial and temporal correlation. Seq2S is demonstrated on time-resolved x-ray phase contrast imaging of liquid jet fuel sprays in a gas turbine combustor, which possesses all of challenges detailed above. Experiments are conducted across four fuels with different breakup morphology using various state-of-the-art methods. Overall, many of the methods failed and Seq2S was most successful: (1) Accurate spray structures were reconstructed with consistent evolution across frames void of artifacts. (2) The performance was robust, invariant to the hyperparameter choice. (3) Computational time is short and can be made eligible for real-time denoising. In particular, the images denoised by Seq2S showed spray droplet diameter distributions with near-zero Kullback–Leibler divergence (0.01 ± 0.01) to a cleaner reference, whereas the second best method yielded 0.06 ± 0.03. This suggests that Seq2S can be reliably used prior to subsequent quantitative spray analyses as it retains (if not, improves) the statistical physical properties of the data.

On the equivalence of the X-ray scattering retrieval with beam tracking and analyser-based imaging using a synchrotron source

X-ray phase contrast imaging (XPCI) methods give access to contrast mechanisms that are based on the refractive properties of matter on top of the absorption coefficient in conventional x-ray imaging. Ultra small angle x-ray scattering (USAXS) is a phase contrast mechanism that arises due to multiple refraction events caused by physical features of a scale below the physical resolution of the used imaging system. USAXS contrast can therefore give insight into subresolution structural information, which is an ongoing research topic in the vast field of different XPCI techniques. In this study, we quantitatively compare the USAXS signal retrieved by the beam tracking XPCI technique with the gold standard of the analyzer based imaging XPCI technique using a synchrotron x-ray source. We find that, provided certain conditions are met, the two methods measure the same quantity.

Experimental and numerical study on the two-phase flow inside a cracked gas diffusion layer of PEMFC

The presence of cracks in the gas diffusion layer (GDL) can have a significant impact on the flow of two phases within Proton Exchange Membrane Fuel Cells (PEMFCs). This study focuses on investigating the transport process of two-phases flow in a GDL sample using both experimental and numerical methods. The porous structure of a hydrophobic carbon paper, serving as the macro-porous substrate (MPS) of the GDL, is examined using synchrotron radiation X-ray phase contrast Computed Tomography (CT). A 3-D model with various crack geometries is then created, and a Lattice Boltzmann Method (LBM) simulation is employed to analyze the flow behavior within the GDL model. The findings reveal that the water intrusion mode in the MPS primarily depends on its hydrophobic nature, but the width and depth of the cracks also significantly influence both the rate and path of water intrusion. Increasing the crack width from 7 μm to 28 μm results in a 30% increment in water intrusion rate, while the intrusion path remains unchanged. However, when the crack width reaches 42 μm, the crack itself becomes the primary path for water intrusion, doubling the intrusion rate. Furthermore, an increase in crack depth leads to a higher invasion rate of the liquid phase, consequently increasing the liquid storage volume within the GDL. This research provides a novel approach for analyzing cracked GDLs and demonstrates the potential to optimize the water management process of PEMFCs through GDL microstructure design.

Operando ultra-high-resolution X-ray microscopy of lithium anodes with separator interactions

Lithium (Li) metal is an attractive anode material candidate for high-energy-density battery systems that could enable challenging electrification applications, such as flight and heavy-duty vehicles. However, the formation of porous deposits and dendrites during cycling cause capacity loss and internal short-circuit risks. Here, we use high-resolution in-situ/operando Zernike phase contrast X-ray microscopy to directly visualize the lithium electrodeposition process inside a coin cell with a commercial separator. The nucleation and subsequent lithium electrodeposition were imaged by transmission X-ray microscopy (TXM) at 150 nm spatial resolution and <2 min temporal resolution. The resulting lithium deposits were then reconstructed into three-dimensional (3D) volumes by computed tomography (CT), revealing the Li structures above, at, and below the anode/separator interface. Distinct nucleation and deposition mechanisms were observed under varied cell temperatures, charging current density, and electrolyte composition. This work demonstrates the unique strengths of combining TXM and CT imaging techniques: the dynamic evolution of lithium electrodeposition and the comprehensive morphology of the resulting structure were characterized together. Furthermore, our results indicate the importance of in-situ/operando characterization of systems in commercially-relevant configurations in developing practical dendrite mitigation strategies.

Virtual histology of Alzheimer’s disease: Biometal entrapment within amyloid-[formula omitted] plaques allows for detection via X-ray phase-contrast imaging

Amyloid-β (Aβ) plaques from Alzheimer’s Disease (AD) can be visualized ex vivo in label-free brain samples using synchrotron X-ray phase-contrast tomography (XPCT). However, for XPCT to be useful as a screening method for amyloid pathology, it is essential to understand which factors drive the detection of Aβ plaques. The current study was designed to test the hypothesis that Aβ-related contrast in XPCT could be caused by Aβ fibrils and/or by metals trapped in the plaques. Fibrillar and elemental compositions of Aβ plaques were probed in brain samples from different types of AD patients and AD models to establish a relationship between XPCT contrast and Aβ plaque characteristics. XPCT, micro-Fourier-Transform Infrared spectroscopy and micro-X-Ray Fluorescence spectroscopy were conducted on human samples (one genetic and one sporadic case) and on four transgenic rodent strains (mouse: APPPS1, ArcAβ, J20; rat: TgF344). Aβ plaques from the genetic AD patient were visible using XPCT, and had higher β-sheet content and higher metal levels than those from the sporadic AD patient, which remained undetected by XPCT. Aβ plaques in J20 mice and TgF344 rats appeared hyperdense on XPCT images, while they were hypodense with a hyperdense core in the case of APPPS1 and ArcAβ mice. In all four transgenic strains, β-sheet content was similar, while metal levels were highly variable: J20 (zinc and iron) and TgF344 (copper) strains showed greater metal accumulation than APPPS1 and ArcAβ mice. Hence, a hyperdense contrast formation of Aβ plaques in XPCT images was associated with biometal entrapment within plaques. Statement of significanceThe role of metals in Alzheimer’s disease (AD) has been a subject of continuous interest. It was already known that amyloid-β plaques (Aβ), the earliest hallmark of AD, tend to trap endogenous biometals like zinc, iron and copper. Here we show that this metal accumulation is the main reason why Aβ plaques are detected with a new technique called X-ray phase contrast tomography (XPCT). XPCT enables to map the distribution of Aβ plaques in the whole excised brain without labeling. In this work we describe a unique collection of four transgenic models of AD, together with a human sporadic and a rare genetic case of AD, thus exploring the full spectrum of amyloid contrast in XPCT.

Morphogenesis of the pulmonary vein and left atrial appendage in human embryos and early fetuses.

The left atrium wall has several origins, including the body, appendage, septum, atrial-ventricular canal, posterior wall, and venous component. Here, we describe the morphogenesis of left atrium based on high-resolution imaging (phase-contrast X-ray computed tomography and magnetic resonance imaging). Twenty-three human embryos and 19 fetuses were selected for this study. Three-dimensional cardiac images were reconstructed, and the pulmonary veins and left atrium, including the left atrial appendage, were evaluated morphologically and quantitatively. The positions of the pericardial reflections were used as landmarks for the border of the pericardial cavity. The common pulmonary vein was observed in three specimens at Carnegie stages 17-18. The pericardium was detected at the four pulmonary veins (left superior, left inferior, right superior, and right inferior pulmonary veins) at one specimen at Carnegie stage 18 and all larger specimens, except the four samples. Our results suggest that the position of the pericardial reflections was determined at two pulmonary veins (right and left pulmonary vein) and four pulmonary veins almost simultaneously when the dorsal mesocardial connection between the embryo and heart regressed. The magnetic resonance images and reconstructed heart cavity images confirmed that the left atrium folds were present at the junction between the body and venous component. Three-dimensional reconstruction showed that the four pulmonary veins entered the dorsal left atrium tangentially from the lateral to the medial direction. More specifically, the right pulmonary veins entered at a greater angle than the left pulmonary veins. The distance between the superior and inferior pulmonary veins was shorter than that between the left and right pulmonary veins. Three-dimensional reconstruction showed that the venous component increased proportionally with growth. No noticeable differences in discrimination between the right and left parts of the venous component emerged, while the junction between the venous component and body gradually became inconspicuous but was still recognizable by the end of the observed early fetal period. The left superior pulmonary vein had the smallest cross-sectional area and most flattened shape, whereas the other three were similar in area and shape. The left atrial appendage had a large volume in the center and extended to the periphery as a lobe-like structure. The left atrial appendage orifice increased in the area and tended to become flatter with growth. The whole left atrium volume^(1/3) increased almost proportionally with growth, parallel to the whole heart volume. This study provided a three-dimensional and quantitative description of the developmental process of the left atrium, comprising the venous component and left atrial appendage formation, from the late embryonic to the early fetal stages.

Grating designs for cone beam edge illumination X-ray phase contrast imaging: a simulation study.

Edge illumination is an emerging X-ray phase contrast imaging technique providing attenuation, phase and dark field contrast. Despite the successful transition from synchrotron to lab sources, the cone beam geometry of lab systems limits the effectiveness of using conventional planar gratings. The non-parallel incidence of X-rays introduces shadowing effects, worsening with increasing cone angle. To overcome this limitation, several alternative grating designs can be considered. In this paper, the effectiveness of three alternative designs is compared to conventional gratings using numerical simulations. Improvements in flux and contrast are discussed, taking into account practical considerations concerning the implementation of the designs.

Quantification of porosity in composite plates using planar X-ray phase contrast imaging

The application of planar Edge-Illumination X-ray Phase-Contrast imaging (EI-XPCi) for the non-destructive quantification of porosity in carbon fiber reinforced polymer (CFRP) specimens, a significant concern in aerospace applications, was investigated. The method enables fast, planar (2D) scans providing access to large samples. A set of woven CFRP plates with porosity content ranging from 0.7% to 10.7% was examined. In addition to standard X-ray attenuation, EI-XPCi provides differential phase and dark-field signals, sensitive to inhomogeneities and interfaces at scales above and below the system spatial resolution, respectively. The correlation with the porosity content from matrix digestion obtained from the dark-field signal was comparable to that from ultrasonic attenuation. The novel analysis of the standard deviation of differential phase (STDP), sensitive to inhomogeneities above the system resolution (approximately 12 μm), resulted in a very high correlation (R2 = 0.995) with the matrix digestion porosity content, outperforming ultrasonic attenuation measurements.

Feasibility and safety of synchrotron-based X-ray phase contrast imaging as a technique complementary to histopathology analysis.

X-ray phase contrast imaging (X-PCI) is a powerful technique for high-resolution, three-dimensional imaging of soft tissue samples in a non-destructive manner. In this technical report, we assess the quality of standard histopathological techniques performed on formalin-fixed, paraffin-embedded (FFPE) human tissue samples that have been irradiated with different doses of X-rays in the context of an X-PCI experiment. The data from this study demonstrate that routine histochemical and immunohistochemical staining quality as well as DNA and RNA analyses arenot affected by previous X-PCI on human FFPE samples. From these data we conclude it is feasible and acceptable to perform X-PCI on FFPE human biopsies.

X-ray 3D Imaging of Low-Density Laser-Target Materials

Achieving optimal design and precise control of the internal structure of laser-target materials are the primary objectives in various laser physics experiments, particularly in generating high flux photon and neutron beams. The study of low-density materials poses considerable challenges for X-ray analysis due to their high transparency and minimal contrast. In this study, to obtain clear visualization of foams with sparse structures, we used phase-contrast X-ray tomography, utilizing a high-quality monochromatic X-ray beam from the synchrotron radiation source PETRA-III at DESY. Employing phase-contrast algorithms, the 3D structure of a foam-suspended glass microsphere inside the plastic cylinder was reconstructed with a level of image quality sufficient to visualize uniformity, displacement, and surface roughness on both sides of the microsphere. The primary focus of this investigation was a CH plastic capillary including 10 mg/cc CHO foam with a glass microsphere positioned at the center. The results of this study demonstrate that phase-contrast X-ray tomography with coherent synchrotron radiation is an effective and valuable technique for the development of new laser targets containing structured low-density materials.