High-resolution X-ray Imaging Research Articles

Eu-doped (Y0.85−xLa0.15)2O3sesquioxide transparent ceramics for high-spatial-resolution X-ray imaging

(Y0.85−xLa0.15)2O3:xEu transparent ceramics have good sensitivity, low detection limits and excellent spatial resolution (18.0 lp mm−1), presenting great potential for high-resolution X-ray imaging applications.

Flexible strontium-based metal–organic framework scintillation screens for high-resolution X-ray imaging

Flexible strontium-based metal–organic framework scintillation screens with strong radioluminescence sensitivity and water resistance were applied for high-resolution X-ray imaging.

Foreign Bodies Detector Based on DETR for High-Resolution X-Ray Images of Textiles

Foreign bodies (FBs) detection for X-ray images of textiles is a novel and challenging task. To solve the problem of poor performance of anchor-based detectors for FBs detection, we propose a feature-enhanced object detection framework with transformer (FE-DETR). Based on the split-attention of residual split-attention network (ResNeSt), we add convolutional block attention module (CBAM) between residual blocks and replace the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times $ </tex-math></inline-formula> 3 convolutional layer of the last residual block with deformable convolution network (DCN) to adapt FBs with different scales. Then, we propose a multiscale feature encoding (MSFE) module to solve the feature dispersion caused by deep convolution. Meanwhile, the transformer module is selected as the prediction head of the detector. During training, several heuristic strategies are used to further optimize the performance of FE-DETR. In addition, we construct a benchmark dataset for the textile FBs detection task. With end-to-end training, FE-DETR achieves higher performance than the baseline and mainstream state-of-the-art methods, with mean average precision (mAP) = 0.74, average precision (AP) = 0.992, average recall (AR) = 0.971, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$F1$ </tex-math></inline-formula> -score = 0.987. This article has been applied to the production line of medical protective clothing during the Corona Virus Disease 2019 (COVID-19) period and has yielded impressive results in actual production.

Lanthanide(III)-Cu4 I4 Organic Framework Scintillators Sensitized by Cluster-Based Antenna for High-Resolution X-ray Imaging.

Scintillator-based X-ray imaging has attracted great attention from industrial quality inspection and security to medical diagnostics. Herein, a series of lanthanide(III)-Cu4 I4 heterometallic organic frameworks (Ln-Cu4 I4 MOFs)-based X-ray scintillators are developed by rationally assembling X-ray absorption centers ([Cu4 I4 ] clusters) and luminescent chromophores (Ln(III) ions) in a specific manner. Under X-ray irradiation, the heavy inorganic units ([Cu4 I4 ] clusters) absorb the X-ray energy to populate triplet excitons via halide-to-ligand charge transfer (XLCT) combined with the metal-to-ligand charge-transfer (MLCT) state (defined as the X/MLCT state), and then the 3 X/MLCT excited state sensitizes Tb3+ for intense X-ray-excited luminescence via excitation energy transfer. The obtained Tb-Cu4 I4 MOF scintillators exhibit high resistance to humidity and radiation, excellent linear response to X-ray dose rate, and high X-ray relative light yield of 29 379±3000 photons MeV-1 . The relative light yield of Tb-Cu4 I4 MOFs is ≈3 times higher than that of the control Tb(III) complex. X-ray imaging tests show that the Tb-Cu4 I4 MOFs-based flexible scintillator film exhibits a high spatial resolution of 12.6lpmm-1 . These findings not only provide a promising design strategy to develop lanthanide-MOF-based scintillators with excellent scintillation performance, but also exhibit high-resolution X-ray imaging for biological specimens and electronic chips.

Experimental validation of a coupling concept for drop formation and growth onto porous materials by high-resolution X-ray imaging technique

Droplets formed on the hydrophobic surface of a porous medium exposed to a cross-flowing gas stream have a strong influence on the mass, momentum, and energy exchange across the porous interface, being of importance in several physical systems and engineering applications, like fuel cells. However, the fluid displacement front is highly complex at the pore-scale, since it is characterized by the surface wettability and a contact angle variation along the triple line. Furthermore, the droplet formation is affected by the pore geometry and the surface wettability. These result in a challenging multi-phase scenario with controversial literature, and few studies consider the detailed mechanism of droplet formation on the surface of the porous medium. In this work, two multi-scale simulations for the emerging water droplet from a single hydrophobic capillary pore opening into the gas phase are validated by a benchmark experiment with the help of a high-resolution X-ray imaging technique to characterize the droplet growing. A three-domain approach (gaseous free flow, interface and porous medium, FIP) was compared with a two-domain approach (based on a free-flow and the porous medium, FP). Whereas the three-domain approach introduces two sets of coupling conditions, one for the free flow-interface and one for the interface-porous medium, the two-domain approach introduces only one set of coupling connections for describing the interaction between the domains. In both approaches, droplet formation and growth alter the coupling conditions between the domains. While the FIP approach treats the porous medium as a continuous matter, it is resolved discretely with the help of a pore network in the FP approach. Both approaches show good agreements with the experimental observations and high correspondences for the drop volume, radii and contact angle evolution. The proposed models provide a base for future developments and help to gain a better insight about the impact of the droplet formation on the interface in a coupled free flow-porous medium system.

Airflow-Controlled Crystallization for a Multi-Inch 2D Halide Perovskite Single-Crystal Scintillator for Fast High-Resolution X-ray Imaging

Airflow-Controlled Crystallization for a Multi-Inch 2D Halide Perovskite Single-Crystal Scintillator for Fast High-Resolution X-ray Imaging

Advancing X-ray Luminescence for Imaging, Biosensing, and Theragnostics.

ConspectusX-ray luminescence is an optical phenomenon in which chemical compounds known as scintillators can emit short-wavelength light upon the excitation of X-ray photons. Since X-rays exhibit well-recognized advantages of deep penetration toward tissues and a minimal autofluorescence background in biological samples, X-ray luminescence has been increasingly becoming a promising optical tool for tackling the challenges in the fields of imaging, biosensing, and theragnostics. In recent years, the emergence of nanocrystal scintillators have further expanded the application scenarios of X-ray luminescence, such as high-resolution X-ray imaging, autofluorescence-free detection of biomarkers, and noninvasive phototherapy in deep tissues. Meanwhile, X-ray luminescence holds great promise in breaking the depth dependency of deep-seated lesion treatment and achieving synergistic radiotherapy with phototherapy.In this Account, we provide an overview of recent advances in developing advanced X-ray luminescence for applications in imaging, biosensing, theragnostics, and optogenetics neuromodulation. We first introduce solution-processed lead halide all-inorganic perovskite nanocrystal scintillators that are able to convert X-ray photons to multicolor X-ray luminescence. We have developed a perovskite nanoscintillator-based X-ray detector for high-resolution X-ray imaging of the internal structure of electronic circuits and biological samples. We further advanced the development of flexible X-ray luminescence imaging using solution-processable lanthanide-doped nanoscintillators featuring long-lived X-ray luminescence to image three-dimensional irregularly shaped objects. We also outline the general principles of high-contrast in vivo X-ray luminescence imaging which combines nanoscintillators with functional biomolecules such as aptamers, peptides, and antibodies. High-quality X-ray luminescence nanoprobes were engineered to achieve the high-sensitivity detection of various biomarkers, which enabled the avoidance of interference from the biological matrix autofluorescence and photon scattering. By marrying X-ray luminescence probes with stimuli-responsive materials, multifunctional theragnostic nanosystems were constructed for on-demand synergistic gas radiotherapy with excellent therapeutic effects. By taking advantage of the capability of X-rays to penetrate the skull, we also demonstrated the development of controllable, wireless optogenetic neuromodulation using X-ray luminescence probes while obviating damage from traditional optical fibers. Furthermore, we discussed in detail some challenges and future development of X-ray luminescence in terms of scintillator synthesis and surface modification, mechanism studies, and their other potential applications to provide useful guidance for further advancing the development of X-ray luminescence.

Beam Trajectory Analysis of Vertically Aligned Carbon Nanotube Emitters with a Microchannel Plate

Vertically aligned carbon nanotubes (CNTs) are essential to studying high current density, low dispersion, and high brightness. Vertically aligned 14 × 14 CNT emitters are fabricated as an island by sputter coating, photolithography, and the plasma-enhanced chemical vapor deposition process. Scanning electron microscopy is used to analyze the morphology structures with an average height of 40 µm. The field emission microscopy image is captured on the microchannel plate (MCP). The role of the microchannel plate is to determine how the high-density electron beam spot is measured under the variation of voltage and exposure time. The MCP enhances the field emission current near the threshold voltage and protects the CNT from irreversible damage during the vacuum arc. The high-density electron beam spot is measured with an FWHM of 2.71 mm under the variation of the applied voltage and the exposure time, respectively, which corresponds to the real beam spot. This configuration produces the beam trajectory with low dispersion under the proper field emission, which could be applicable to high-resolution multi-beam electron microscopy and high-resolution X-ray imaging technology.

Lead-Free Cesium Manganese Halide Nanocrystals Embedded Glasses for X-Ray Imaging.

The toxicity of heavy-metal Pb and instability of lead-based halide perovskite nanomaterials are main factors to impede their practical applications in the fields of solar cells, LEDs and scintillators. In this paper, all inorganic lead-free cesium manganese halidenanocrystals are synthesized in glass for the first time. Red photoluminescence with broad PL band, negligible self-absorption and a high photoluminescence quantum yield of 41.8% is obtained. In addition, modulating halide component can change the Mn2+ ions coordination environment to obtain tunable photoluminescence from red to green. More importantly, cesium manganese halidenanocrystals embedded glasses exhibit outstanding long-term stabilities. Theses cesium manganese halide nanocrystals embedded glasses are also highly stable against high energy irradiation and exhibit highly efficient radioluminescence, making them promising for high-resolution X-ray imaging. These results demonstrate that cesium manganese halide nanocrystals embedded glasses are promising eco-friendly candidates for applications in light-emitting diodes and scintillators.

Unique bone microanatomy reveals ancestry of subterranean specializations in mammals.

Acquiring a subterranean lifestyle entails a substantial shift for many aspects of terrestrial vertebrates' biology. Although this lifestyle is associated with multiple instances of convergent evolution, the relative success of some subterranean lineages largely remains unexplained. Here, we focus on the mammalian transitions to life underground, quantifying bone microanatomy through high-resolution X-ray tomography. The true moles stand out in this dataset. Examination of this family's bone histology reveals that the highly fossorial moles acquired a unique phenotype involving large amounts of compacted coarse cancellous bone. This phenotype exceeds the adaptive optimum seemingly shared by several other subterranean mammals and can be traced back to some of the first known members of the family. This remarkable microanatomy was acquired early in the history of the group and evolved faster than the gross morphology innovations of true moles' forelimb. This echoes the pattern described for other lifestyle transitions, such as the acquisition of bone mass specializations in secondarily aquatic tetrapods. Highly plastic traits-such as those pertaining to bone structure-are hence involved in the early stages of different types of lifestyle transitions.

Demonstration of the X-ray imaging capabilities of the newly installed multilayer monochromator at SPring-8 BL20B2

Double multilayer monochromators (DMMs) for 40 keV and 110 keV have been installed at BL20B2 in SPring-8. The DMMs provide X-rays with a few percent bandwidths at those energies. The flux density of the X-rays is more than several hundred times higher than that of monochromatic X-rays with a silicon double crystal monochromator, which enables us to perform high-speed X-ray imaging with a large field of view and high spatial resolution X-ray imaging in those high-energy X-rays. Here characteristics of DMMs and some demonstrations of X-ray imaging using the high flux density beams are shown.

Investigation of pore formation mechanisms induced by spherical-powder delivery in directed energy deposition using in situ high-speed X-ray imaging

• Pore formation mechanisms unique to the spherical-powder delivery in laser DED AM were revealed. • The pore formation dynamics were directly observed by high-speed synchrotron X-ray imaging. • A powder delivered to a front laser-beam region or melt pool interacted with melt flow and caused pores. • The delivered particle would change the pore size on its trajectory. • A space induced by the delivered spherical particle led to pore formation. In the laser-based directed energy deposition (DED) process, blown powder additive manufacturing (AM), either spherical or irregular metal particles can be used as the feedstock material to be delivered into a melt pool for fabrication. The delivered particles interact with the melt flow in different regions of melt pool, and the interactions between the liquid melt pool and the spherical particles are different from those between the melt pool and irregular particles. The objective of this investigation is to reveal the mechanisms and dynamics of pore formation unique to spherical-powder delivery in the laser DED AM process. In situ high-speed and high-resolution X-ray imaging showed that delivered spherical particles could induce pore formation mechanisms through the interactions between the melt pool and the particle front surface, the particle side surface, or the particle back surface. These results indicate that spherical particles induce different pore formation mechanisms from irregular particles. This fundamental understanding will benefit further investigations into reducing porosity and improving DED-fabricated part quality.

Temperature dynamic compensation vertical Bridgman method growth of high-quality GaSb single crystals

Gallium antimonide (GaSb) is considered an ideal substrate for heterostructure growth. A significant property that inhibits the widespread application of infrared plane-array detector growth on GaSb is the crystal quality of the starting substrate. Herein, we report the growth of single-crystal GaSb by a temperature dynamic compensation vertical Bridgman (TDC-VB) method. This approach offers a low temperature gradient and a stable solid–liquid interface position in the furnace during the growth process. Two inch diameter twin-free GaSb single crystals with (100) orientation have been reproducibly obtained using the TDC-VB method. The crystalline character of the obtained GaSb has been examined by optical microscopy (OM), high-resolution X-ray diffraction (HRXRD), X-ray tomography (XRT), and Fourier-transform infrared (FTIR) spectroscopy. The etch pit dislocation density (EPD) of the GaSb polished wafers (100) was 6–72 cm−2, and the full-width at half-maximum (FWHM) of the Bragg diffraction peak was 15.4″. A uniform XRT image was obtained, and ca. 50 % of the GaSb wafers, which were produced by one crystal, showed transmittance > 20 % at 10 µm, indicating the formation of high-quality GaSb crystals. This work provides useful guidelines for the formation of high-quality GaSb crystals with significant promise for substrate applications.

One-pot synthesis of lanthanide-activated NaBiF4 nanoscintillators for high-resolution X-ray luminescence imaging

Nanocrystal scintillators have attracted considerable attention due to their attractive facile solution-processed thin-film fabrication and tunable X-ray luminescence, and thus hold promise for manufacturing next-generation scintillation screens for high-resolution X-ray imaging. Current inorganic scintillators usually have drawbacks of time-consuming preparation, toxic components, and rigorous synthesis conditions at a relatively high temperature. Here, we report a one-pot green synthesis strategy for readily scaling-up preparation of eco-friendly, lanthanide-doped NaBiF4 nanoscintillators. These nanoscintillators feature efficient X-ray absorption due to the high-Z bismuth element and tunable radioluminescence in the visible region through rational lanthanide doping. We demonstrate a laminating-annealing technology to fabricate large-area scintillation screen (Ø = 5 cm) using these NaBiF4 nanoscintillators for high-resolution X-ray imaging with a spatial resolution of 9 line pairs per millimeter (lp mm−1). Our study offers new ways to transport low-cost synthesis of high-quality nanoscintillators for high-performance digital radiography.

Intermittency of Rock Fractured Surfaces: A Power Law

Roughness of rock fractured surfaces is one of the most important factors controlling fluid flow in rock masses. Roughness quantification is of prime importance for modelling the flow of ground waters as well as reservoir fluid mechanics. In this study, with the aid of high-resolution 3D X-ray CT scanning and image processing techniques, the roughness of four different rock types is reconstructed with a resolution of 16.5 microns. Moreover, the correlation and structure functions are used to analyse height fluctuations as well as statistical intermittency of the studied rock fractured surfaces. It is observed that at length scales smaller than a critical length scale, fractures surfaces are correlated and show multifractality. Monofractals are neither intermittent nor correlated; hence, a meaningful link between statistical intermittency and the correlation function of multifractals is expected. However, a model that considers this relationship and predicts multifractal spectra of disordered systems is still missing. A simple power law that can exactly forecast the multiscaling spectrum of rock fracture process zone is being introduced. It is explained how the exponent of this power function λi is related to the crossover length of correlation function ξ, and how this critical length scale can be objectively identified.

High-throughput production of LuAG-based highly luminescent thick film scintillators for radiation detection and imaging

Radiography is non-destructive imaging for engineering, medical diagnostics, airport security checks, and decontamination activities in nuclear plants. Inorganic scintillators are phosphor materials that convert radiation into visible photons with high luminescence and fast response, and scintillators with a few tens of micrometers thickness can improve sensitivity in radiation detection and imaging. To date, a production method for thick film scintillators is a time and cost consuming way of slicing and poshing bulk single crystals and transparent ceramics. Here, the chemically vapor deposited Ce3+-doped Lu3Al5O12 thick film scintillators (CVD-Ce3+:LuAG) with a thickness of 1–25 μm were produced at deposition time of 1–30 min. Numerical simulations indicated the penetration depth of α-particle in Ce3+:LuAG is 12.8 μm, and the 14-μm-thick CVD-Ce3+:LuAG showed highest light yield (31,000 photons 5.5 MeV−1), superior to the commercial Ce3+:LuAG single crystal scintillator (21,000 photons 5.5 MeV−1). In the X-ray radiograph taken with CVD-Ce3+:LuAG as a scintillation screen, 5-μm-width bar of metal microgrids can be identified. Vapor deposition technique can be a novel high-throughput production way of a thick film scintillator which is in a micrometer-thickness effective to converting radiations into photons for sensitive α-emitter detection and high-resolution X-ray imaging.

Hoop Strain Measurement During a SiC/SiC Ceramic Composite Tube Burst Test by Digital Volume Correlation of X-Ray Computed Tomographs

BackgroundSilicon carbide-fibre/silicon carbide matrix (SiC/SiC) composites are candidate materials for accident tolerant fuel cladding in light water and advanced gas cooled nuclear fission reactors. The mechanical and damage behaviour of ceramic composites is sensitive to the composite geometry, the microstructure and the loading state. Reliable test methods are needed to investigate the subcritical damage that affects hermetic properties and strength, and this requires precise measurements under loading states that are representative of operating conditions.ObjectiveThe objective was a novel methodology to measure the deformation of an internally pressurised ceramic composite tube.MethodsA burst test of an internally ground SiC/SiC (filament wound and braided) ceramic composite tube, pressurized by radial expansion of a compressed elastomer insert, was observed in situ by high resolution (synchrotron) X-ray tomography. The full field three-dimensional displacements were measured by digital volume correlation, with a precise rotation correction applied to obtain the relative radial and circumferential displacements of the tube wall for the first time.ResultsThe hoop strain, and its spatial variations, were determined as a function of the applied hoop stress and showed ovalisation and barreling of the tube. The quantity of subcritical matrix cracking increased with the tensile hoop strain, but the critical crack that caused rupture was not at the location of maximum tensile strain.ConclusionPrecise measurements of the deformation during the burst test found non-uniform hoop strains that caused a non-uniform distribution of subcritical cracking, which could influence the hermetic properties and strength.

Enhancing light yield of Tb3+-doped fluoride nanoscintillator with restricted positive hysteresis for low-dose high-resolution X-ray imaging

Enhancing light yield of Tb3+-doped fluoride nanoscintillator with restricted positive hysteresis for low-dose high-resolution X-ray imaging

Large-Area Laminar TEA2MnI4 Single-Crystal Scintillator for X-ray Imaging with Impressive High Resolution.

Current X-ray imaging scintillators are dominated by inorganic scintillators grown through a high-temperature process. Exploring new types of scintillators with mild growth conditions, high light yields, and eco-friendly chemical compositions is essential and challenging. Herein, the zero-dimensional large-area laminar organic-inorganic hybrid metal halide TEA2MnI4 (TEA = tetraethylammonium) single crystal with dimensions of 50 mm × 60 mm × 0.82 mm is grown via a local-heating solvent evaporation method. Compared with its Cl- and Br-based counterparts, the incorporation of the iodine component enhances the X-ray attenuation ability and significantly accelerates the decay of the photoluminescence of TEA2MnI4. Interestingly, the prepared TEA2MnI4 exhibits a high transmittance of >90% over the range of 515-765 nm and exhibits a high light yield of 26288 photons/MeV, which provides the prerequisite for high-resolution X-ray imaging. The TEA2MnI4 single-crystal scintillator displays an astonishing spatial resolution exceeding 25 line pairs per millimeter, which provides a design concept for a Mn-I-based single crystal for high-performance scintillator applications.

A Weakly supervised approach for thoracic diseases detection

Medical image analysis has become increasingly important as it can effectively assist health care providers with precise clinical diagnosis decisions. Thoracic diseases are one of the leading causes of death in the U.S. Accurate and reliable thoracic disease classification plays a crucial role in early diagnosis and consequently proper treatment plans by providing great assistance to physicians. In the health care domain, clinical diagnoses and decisions are made based on specialist’s opinions which is a tedious and error-prone process. Therefore, computer-aided systems are significantly applied to help health care administrations in decision making as a decision support. Deep learning approaches have shown promising potential in clinical image processing. In this study, an online feature selection method for efficient sampling of high-resolution X-ray images is proposed. A weakly-supervised approach that combines DenseNet-121 layers with a saliency sampling approach to extract the most informative parts or pixels of the input images is proposed. Unlike uniform sampling, the proposed approach preserves the spatial information of input images contributing to an accurate prediction. Performance of the proposed model is evaluated using two public chest X-ray datasets including ChestX-ray14 and CheXpert. The final model that aggregates the predictions over multiple sampling of the input image achieves the averaged AUC of 0.890 and 0.921 for ChestX-ray14 and CheXpert datasets, respectively. Our results for thoracic disease detection demonstrate that the proposed approach can effectively improve the performance of the thoracic disease prediction by identifying and preserving the most important parts of the input images.