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• We analyze testing protocols used for Covid-19 detection used in the literature. • We successfully classify COVID images whose lungs areas are turned to black. • We try using different datasets for training and testing. • We show that many highly cited paper on this topic use biased testing protocols. In this paper, we compare and evaluate different testing protocols used for automatic COVID-19 diagnosis from X-Ray images in the recent literature. We show that similar results can be obtained using X-Ray images that do not contain most of the lungs. We are able to remove the lungs from the images by turning to black the center of the X-Ray scan and training our classifiers only on the outer part of the images. Hence, we deduce that several testing protocols for the recognition are not fair and that the neural networks are learning patterns in the dataset that are not correlated to the presence of COVID-19. Finally, we show that creating a fair testing protocol is a challenging task, and we provide a method to measure how fair a specific testing protocol is. In the future research we suggest to check the fairness of a testing protocol using our tools and we encourage researchers to look for better techniques than the ones that we propose. [ABSTRACT FROM AUTHOR]

Crystal growth rate was greatly controlled through volatilization control valve, which avoid producing a large number of defects because of high growth rate. Constant growth rate leads to high-quality single crystal for high sensitive X-ray detector. [Display omitted] Halide perovskite single crystals (HPSCs) provide a unique platform to study the optoelectronic properties of such emerging semiconductor materials, while the temperature induced crystal growth method often has an increased solute integration speed and/or unavoidable solute consumption, resulting in a soaring or slumping crystal growth rate of HPSCs. Here, we developed a universal and facile solvent-volatilization-limited-growth (SVG) strategy to finely control the crystal growth rate by the fine-control-valve for high quality crystal grown through solution processes. The grown HPSCs by SVG method exhibited a record low trap density of 2.8 × 108 cm−3 and a high charge carrier mobility-lifetime product (μτ product) of 0.021 cm2/V, indicating the excellent crystal quality. The crystal surface defects were further passivated by oxygen suppliers as Lewis base, which led to a reduction of surface leakage current by two times when using for low dose rate X-ray detection. Such HPSC X-ray detector displayed a high sensitivity of 1274 µC/(Gy air cm2) with a lowest detectable dose rate of 0.56 μGy air /s under 120 keV hard X-ray. Further applications including alloy composition analysis and metal flaw detection by HPSC detectors were also demonstrated, which not only shows the bright future for product quality inspection and non-destructive materials analysis, but also paves the way for growing high quality single crystals and fabricating polycrystalline films. [ABSTRACT FROM AUTHOR]

[Display omitted] • We structure the GDN and LRN with translational invariance as the primary consideration. • We implement the multi-task strategy to improve the GDN's generalization. • The proposed method has robust translational invariance. Recently, intelligent cephalometric landmark detection systems that employ deep convolutional neural networks (DCNNs) have been widely developed. In this paper, we concentrate on two challenging difficulties of DCNNs based cephalometric landmark detection. First, previous DCNN methods usually decreased the resolution of high-resolution cephalometric images. Hence, the trained DCNNs missed the detailed local features of original images. Moreover, the detected landmarks' locations were recovered using a fixed ratio, so location error was increased after recovery. Second, the performance of cephalometric landmark detection is dependent on DCNNs' translational invariance because the target landmarks' locations are influenced by any shift of the cephalometric images. However, modern DCNNs have limited translational invariance, and previous DCNN methods did not take translational invariance into consideration. In this paper, we developed the widely used two-stage framework to resolve the above two challenges. In the first stage, we train a global detection network, which receives the whole images as input, to generate candidate landmarks. In the second stage, we split the input image into patches and train a local refine network, which receives image patches as input, to refine the landmarks' locations. The proposed local refine network can produce accurate landmarks' locations because it entirely focuses on the detailed local features of high-resolution cephalometric images. The global detection network and local refine network are structured with translational invariance as their primary consideration. The proposed method achieved robust performance on a private dataset and the public Automatic Cephalometric X-ray Landmark Detection Challenge 2015 dataset. [ABSTRACT FROM AUTHOR]

X-ray detection and imaging have arose lots of attentions in modern society, due to its stronger penetrating ability. This review highlights the potential of different kinds of halide perovskites for direct X-ray detector and imager, and systematically summaries current progress on them, as well as a brief outlook presents for further boosting their performances. [Display omitted] X-ray detection has significantly applied in medical diagnostics, railway flaw detection, security screening, non-destructive testing in industrial products and quality inspection in food industry et al. Recently, as one of the alternative materials, halide perovskites show great potential in high-performance X-ray detector for their relatively high atomic number, superior carrier life-time produce, tunable band gap, and low temperature fabrication process. Accordingly, based on halide perovskite, some advanced and meaningful work was conducted, and corresponding performances of X-ray detector have reached a comparative height. Herein, we aim at systematically summarizing current progress on halide perovskite based X-ray detectors: (1) First, an introduction of background and key parameters is provided to understand the X-ray detectors clearly; (2) After that, we put an emphasis on the advanced work for various halide perovskites based X-ray detectors. Meanwhile, their optimized strategies and applications in imaging are presented; (3) Finally, the challenges remained and promising opportunities are also presented, for further boosting the performance of halide perovskites based X-ray detectors. [ABSTRACT FROM AUTHOR]

• This work proposes a Modified VGG19 deep-learning architecture to diagnose the Chest X-Rays. • This work computes the essential handcrafted features from the Chest X-Rays. • This work introduces an Ensemble of Features Scheme (EFS) by integrating the deep-features and the handcrafted features. • Serial fusion and PCA based selection is implemented in EFS to choose primary feature set. • Experimental results demonstrate superior performance of Modified VGG19 in comparison with AlexNet, VGG16, VGG19 and ResNet50. Pneumonia is one of the major illnesses in children and aged humans due to the Infection in the lungs. Early analysis of pneumonia is necessary to prepare for a possible treatment procedure to regulate and cure the disease. This research aspires to develop a Deep-Learning System (DLS) to diagnose the lung abnormality using chest X-ray (radiograph) images. The proposed work is implemented using; (i) Conventional chest radiographs and (ii) Chest radiograph treated with a threshold filter. The initial experimental evaluation is carried out using the traditional DLS, such as AlexNet, VGG16, VGG19 and ResNet50 with a SoftMax classifier. The results confirmed that, VGG19 provides better classification accuracy (86.97%) compared to other methods. Later, a customized VGG19 network is proposed using the Ensemble Feature Scheme (EFS), which combines the handcrafted features attained with CWT, DWT and GLCM with the Deep-Features (DF) achieved using Transfer-Learning (TL) practice. The performance of customized VGG19 is tested using different classifiers, such as SVM-linear, SVM-RBF, KNN classifier, Random-Forest (RF) and Decision-Tree (DT). The result confirms that VGG19 with RF classifier offers better accuracy (95.70%). When the similar experiment is repeated using threshold filter treated chest radiographs, the VGG19 with RF classifier offered superior classification accuracy (97.94%). This result confirms that, proposed DLS will work well on the benchmark images and in the future, it can be considered to diagnose clinical grade chest radiographs. To create your abstract, type over the instructions in the template box below. Fonts or abstract dimensions should not be changed or altered. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Lead halide perovskites with excellent optoelectronic properties have attracted extensive attention and made amazing progress for X-ray detectors and imaging. However, lead is highly toxic to humans, animals and ecosystems, posing a great safety concern to its commercial application. It has become an urgent need to develop stable and environment-friendly lead-free alternatives. In this review, we summarize recent progress in lead-free halide perovskites (LFHPs) and derivatives toward X-ray detectors and imaging. First, we introduce the working principle of X-ray detectors and the key figure of merit in direct and indirect detection processes. In addition, we summarize state-of-the-art lead-free halide perovskites preparation methods. Furthermore, we comprehensively discuss the structural dimensions, optoelectronic properties of lead-free halide perovskites and their recent advances in X-ray detection and imaging. Meanwhile, the stabilities of LFHPs-based X-ray detectors are discussed. Finally, we outline several main issues of state-of-the-art LFHPs-based X-ray detectors and provide prospects to overcome these limitations. [ABSTRACT FROM AUTHOR]

• The bond-slip performance of the steel fibers in the SIFCON matrix is improved by increasing the quantity of plastic hinges, the length of the end hook, and the embedment length. • The novel half-hooked steel fiber and the novel end-hook steel fiber have a stronger bonding effect. Half-hooked steel fiber selected 60° end hook bending angle mechanical properties of the best. • The single steel fiber anchorage performance evaluation index K was proposed based on the average bond strength, equivalent bond strength, pullout energy, and max tensile stress, and K can effectively demonstrate the anchorage effect of each specimen. • The existence of the "local damage" stage was verified by experimental data, experimental phenomena, and X-ray inspection, and it was found that the "local damage" was more obvious in the moderately strength SIFCON matrix. • For the moderately strength SIFCON matrix, the enhanced end-hook steel fiber and half-hooked steel fiber bond-slip equation are more suitable. the calculated value is closer to the experimental value, and complements the second peak pullout load calculation equation for the half-hooked steel fiber. In this study, an attempt was made to study the bond-slip performance of end-hook and half-hooked steel fibers embedded in moderately strength SIFCON matrix, to find out the cause of excessive mechanical anchorage and to further optimize the bond-slip equation of steel fibers. Used end-hook steel fibers with embedded depths 10 and 15 mm, pullout offset angles 0°, 30°, 45°, and 60°; Half-hooked steel fiber with embedded depths 10 and 15 mm, end-hook bending angles 30°, 45°, 60°, and 90°; Novel end-hook and novel half-hooked steel fibers with end-hook length doubled, which were subjected to a static pullout test at a rate of 0.01 mm/s. Experiments showed that the half-hooked steel fiber took the best end-hook bending angle at 60°; The novel end-hook and half-hooked steel fiber had a good bonded performance. The single steel fiber anchorage performance evaluation index K was proposed. Through experimental phenomena, data analysis, and X-ray flaw detection, the existence of "local damage" was proved. Based on the traditional bond-slip formulation, a new bond-slip formulation for moderately strength SIFCON substrates is proposed by adding a plastic hinge in the "local damage" region. By comparing the old and new equation, it was found that the calculation error of the maximum pullout load of end-hook steel fibers was reduced by 3.77 times and that the calculation error of the maximum pullout load of half-hooked steel fibers was reduced by 2.8 times, and the calculation equation for the peak load of secondary reinforcement of half-hooked steel fiber was supplemented, which is of application value for further optimization of the shape of steel fibers. [ABSTRACT FROM AUTHOR]

This study used dodecylamine (DDA) as a collector to explore the role and adsorption mechanism of a new regulator sodium monododecyl phosphate (SMP) on the flotation separation of brucite and calcite. A microflotation test revealed that only 2 mg/L of SMP could considerably increase the flotation recovery of calcite and achieve a difference in flotation recovery of up to 75.85 % between brucite and calcite. The adsorption capacity measurements indicated that SMP selectively increase the adsorption capacity of calcite for DDA. Contact angle measurements showed that the presence of SMP greatly increased the contact angle of calcite while slightly decreasing the contact angle of brucite. Infrared spectrum analysis, zeta potential detection and X-ray photoelectron spectroscopy revealed that the adsorption of SMP onto the brucite surface is not conducive to the adsorption of DDA onto the brucite surface; meanwhile, the adsorption of SMP onto the calcite surface promoted the adsorption of DDA onto the calcite surface and activated the flotation of calcite. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • WO 3 shows X-Ray induced photochromic properties by W6+ to W5+. The transformation of tungsten oxide from yellow (without X-ray) to blue green (60 min) under X-ray radiation of varying duration, and it is a continuous process. Under X-ray irradiation treatment, some of the W-O bonds break, causing the oxygen molecules to leave the surface lattice and creating oxygen vacancies. One oxygen vacancy in WO 3 generally causes two electrons, which reduces W6+ ions into W5+. The product is H x WO 3 , resulting in a reduction in the crystalline volume and band gap of the sample. Simultaneously thermally annealed pre- and post-X-ray irradiation samples, both of which are the same color after cooling. This new finding extends the photochromic energy range of tungsten oxide and has important implications for the design and fabrication of other X-ray-induced photochromic materials for charge transfer, which will certainly benefit the development of next-generation X-ray detection materials. [ABSTRACT FROM AUTHOR]

Tb3+/Dy3+ ions doped SiO 2 -B 2 O 3 -Gd 2 O 3 -CaO (SBGOTD) and SiO 2 -B 2 O 3 -GdF 3 -CaO (SBGFTD) two series of glass were synthesized using a high-temperature melting method. The luminescence and scintillation properties of both glass series were studied through photoluminescence (PL) spectroscopy and X-ray emission spectroscopy. In the two series of glass, the SBGFTD (Dy3+,0.5 mol%) glass sample exhibited the best luminous intensity excited at 378 nm and X-ray. The PL emission intensity and fluorescence decay time of Tb3+ were observed to change, indicating that energy was transferred from Dy3+ to Tb3+ ions. In addition, the integrated scintillation efficiencies of the two series glass samples reached 36.8 (SBGOTD) and 38.2% (SBGFTD) of the Bi 4 Ge 3 O 12 (BGO) standard sample. The practical application of fluorine-modified borosilicate glass in the fields of luminescence and X-ray detection can be further expanded and improved based on these findings. [ABSTRACT FROM AUTHOR]

Metal halide perovskites have gained significant attention as promising materials for ionizing radiation detection due to their facile fabrication process, exceptional optoelectronic properties and high attenuation coefficients. To effectively absorb the incident X-ray photons, thick active layers have been reported and fabricated via spray-coating. However, the conventional spray-coating method is susceptible to various adverse effects, making it challenging to achieve high-quality thick perovskite films. In this work, we propose the use of antisolvent-assisted spray-coating to deposit perovskite films, which results in small surface roughness, thick films on various substrates. The slow growth of the thick film and the ability to regulate its crystallization through the modulation of processing atmosphere were also carefully studied. The optimized X-ray detector demonstrated a sensitivity of up to 3370.8 μC Gy air −1 cm−2, demonstrating its great potential for X-ray detection applications. • Anti-solvent spray-coating technique was established to deposit perovskite thick films. • The spray-coating process was systematically investigated and optimized. • Optimized devices based on antisolvent-assisted X-ray detectors are promising for real applications. [ABSTRACT FROM AUTHOR]

• Cu 2 Se/x%Y 2 O 3 composites were fabricated using solid state recation. • The oxidation states are confirmed by XPS studies. • Composite samples exhibit enhanced micro- hardness. • The lowest resistivity was observed for the sample with x = 0.25 wt%. • The highest power factor was exhibited for the sample with x = 0.75 wt%. In this study, we have investigated the structural, thermal, electrical, and mechanical properties of the composite system Cu 2 Se/ x % Y 2 O 3 (0 ≤ x ≤ 1.00) as a function of varying Y 2 O 3 concentration, x. The successful incorporation of Y 2 O 3 in the Cu 2 Se matrix is carried out using the solid-state reaction method, and the same is confirmed by X-ray diffraction analysis. Due to the low concentration of Y 2 O 3 , all the prepared composites exhibit monoclinic crystal structure with P2/m space group within the X-ray detection limit at room temperature. The oxidation state of the studied composites is investigated using X-ray photoelectron spectroscopy (XPS). The composites exhibit an increase in mechanical hardness as a function of Y 2 O 3 concentration, whereas the electrical resistivity shows no systematic variation with Y 2 O 3 concentration. The highest resistivity is observed for the sample with x = 1%. The measured Seebeck coefficient (S) value increases with increasing temperature. The positive values of S indicate that the positive charge carriers (holes) dominate the thermoelectric transport. The thermal conductivity of the composites increases as compared to the Cu 2 Se pristine sample. The overall power factor and ZT of studied composites were found to decrease with the addition of Y 2 O 3 to the Cu 2 Se system. [Display omitted] Temperature dependent thermoelectric quality factor of Cu 2 Se/x% Y 2 O 3 compounds [ABSTRACT FROM AUTHOR]

X-ray free-electron lasers (XFEL) provide unique opportunities for hard X-ray emission spectroscopy (XES) in solution phase by enabling femtosecond temporal resolution. The high brilliance and MHz repetition rate of such sources drive the development of specialized sample delivery systems to overcome the challenges of sample degradation, as well as major advances of multiple-gain detectors to fully utilize the high dynamic range required for X-ray detection. This paper addresses the experimental limitations that arise in a typical XES experiment performed on fast liquid jets at the MHz repetition rate of the European XFEL. Using a low-noise gain-switching JUNGFRAU detector allows taking advantage of the high dynamic range and high sensitivity, but restricts a single-shot detection due to the limited frame rate. The gain transition regions of the detector response may exhibit nonlinear behavior that can be identified and efficiently corrected using the internal reference-based normalization and linearization approaches described here. [ABSTRACT FROM AUTHOR]

Silicon carbide fibre/silicon carbide (SiC f /SiC) composites are important for manufacturing the hot-section components of aero engines and supersonic vehicles. Hence, quality control, as well as qualitative and quantitative non-destructive testing and evaluation (NDT&E) are critical. A grey (G) value method for the characterisation and NDT&E of manufacturing defects in SiC f /SiC composites based on the attenuation behaviour of low-energy X-rays was proposed, and a digital X-ray imaging detection system was developed. Specimens with artificial and manufacturing defects were evaluated, thereby revealing that imperfections were induced when the SiC f /SiC composites were formed at the high-temperatures; microcracks (100-μm-wide) and rectangular defects (0.1-mm-deep) were detected with a sensitivity exceeding 100 μm. Our results demonstrated that 'voids', 'microcracks', 'porosity', 'polymer impregnation inhomogeneity', 'fibre-lack', and 'gap-delamination' were the typical manufacturing defects caused during formation of SiC f /SiC composites at high temperatures; the minimum deviation between the detected and designed length of a 10-mm-long microcrack in the 3.0-mm-thick SiC f /SiC composite specimen was ~3%; the manufacturing defects were effectively characterised and evaluated using the distribution behaviours of G values and digital radiographic imaging features. Image 1 [ABSTRACT FROM AUTHOR]

The urgent demand for radiation detection in diverse applications boosts extensive investigations on scintillators. However, the current scintillating materials are mostly limited to mono-crystals with high cost, restricted volume and time-consuming fabrication techniques. Here, we report an efficient and transparent Tb3+-doped Sr 2 GdF 7 glass ceramic (GC) prepared via simple melt-quenching method, and its optical response to X-ray. By incorporating Tb3+ into crystallized Sr 2 GdF 7 inside a typical aluminosilicate glasses, highly enhanced green emission was observed under UV and X-ray excitation. After thermal treatment, the internal and external photo-luminescence quantum yields can be as high as 59.1 and 26.4%, respectively, with the high transparency (65%@550 nm) preserved. More interestingly, this composite material, combining the advantages of oxide glasses and fluoride crystals, presents strong X-ray excited luminescence (XEL). Its XEL intensity is 194% of that of commercial BGO scintillator. Evidenced by detailed optical and structural properties, it can be concluded that rare earth ions activated bulk oxyfluoride glass ceramics with unique merits, such as low-cost, high efficiency and intense radio-luminescence, could be alternative scintillating materials for high energy ray detection. [ABSTRACT FROM AUTHOR]

Europium doped borosilicate glasses were prepared in CO reducing atmosphere. The glasses were systematically investigated through XPS, photoluminescence (PL), fluorescence decay curves and X-ray excited luminescence (XEL). XPS results show that the glasses contain Eu2+ and Eu3+ at the same time. Under the excitation of 360 nm light, only a broad blue emission with peak around 440 nm due to the 5d→4f transition of Eu2+ is observed, while the emissions from Eu3+ do not appear in the PL spectra. The fluorescence decay curves were monitored at 440 nm, and the measured lifetimes are in the range of 0.17–0.42 μs. The PL results indicate that the PL emission from Eu2+ is significantly intense than the PL emissions from Eu3+. Upon X-ray excitation, two main emissions with peaks at 445 nm and 616 nm corresponding to Eu2+ and Eu3+ are obtained. The XEL results reveal that the XEL emissions from Eu3+ are comparably intense as the XEL emission from Eu2+. The results indicate that europium doped borosilicate glass could be a potential scintillating material in X-ray detection filed. [ABSTRACT FROM AUTHOR]

4H-SiC Schottky photodiodes, with 25 μ m epitaxial layers, employing thin (20 nm) Ni 2 Si Schottky contacts, were investigated for high temperature photon counting X-ray spectroscopy. Important X-ray photodiode detector parameters were extracted from electrical characterization within the temperature range 160 °C to 0 °C. The devices were found to be fully depleted at an applied electric field of 20 kV/cm; a leakage current density of 33 nA cm -2 ± 1 nA cm−2 at 160 °C, was measured for one of the devices. The detectors were subsequently connected to low-noise photon counting readout electronics and investigated for their spectral performance at temperatures up to 100 °C. With the charge-sensitive preamplifier operated at the same temperature as the detector the best energy resolution (Full Width at Half Maximum at 5.9 keV) obtained decreased from 2.20 keV ± 0.04 keV (120 e − rms ± 2 e − rms) at 100 ∘ C to 1.20 keV ± 0.03 keV (65 e - rms ± 2 e − rms) at 0 ∘ C. The dominant source of noise broadening the 55Fe X-ray photopeak was found to be the dielectric noise, except for the spectra accumulated at 100 °C and long shaping times (> 6 μ s), in those case the main source of photopeak broadening was the white parallel noise. [ABSTRACT FROM AUTHOR]

State-of-the art X-ray imaging cameras using silicon sensors for X-ray detection have demonstrated a frame-rate of 10 MHz and excellent performance for X-ray energies below 20 keV. We proposed a pixelated ultrafast inorganic scintillator-based front imager for GHz hard X-ray imaging. The proposed imager is featured with a total absorption for hard X-ray photons, and provides sub-ns scintillation pulse width crucial for X-ray bunches of a few ns spacing foreseen at the proposed MaRIE facility. We measured temporal response of a dozen ultrafast and fast inorganic scintillators at the 10-ID-B site of the Advanced Photon Source (APS) of ANL. Crystal's response to hybrid X-ray beam of 30 keV, consisting of singlet bunches of 50 ps width and septuplet bunches of 27 ps width with 2.83 ns bunch spacing, was measured. Ultrafast inorganic scintillators, such as BaF 2 :Y and ZnO:Ga, show clearly resolved X-ray bunches for septuplets, as well as no degradation of amplitude for continuous eight septuplets, providing a proof of principle for the ultrafast inorganic scintillator-based total absorption front imager for the proposed MaRIE project. [ABSTRACT FROM AUTHOR]

We report on the synthesis and characterization of composite semiconducting polymer – nanoparticle membranes for X-ray detection applications. The membranes are made of poly(vinyl alcohol) (PVA) organic polymer that is doped with ionic liquid (IL) to control its electrical conductivity. Tl 2 O 3 nanoparticles with different weight concentrations are added to the polymer, and membranes are produced using solution casting method. The nanoparticles are synthesized using a microwave assisted technique under controlled temperature and pressure, and their average size is 13.0 ∓ 1.9 nm. Structural and compositional tests confirm the fabrication of homogeneous polymer-nanoparticle films. Electrical impedance tests are conducted as a function of nanoparticle concentration and temperature for the membranes, and they reveal that the dc electrical resistance of the membranes decreases with increasing both nanoparticle concentration and temperature. The activation energy was found to increase with increasing nanoparticle concentration. The membranes are utilized as conductometric X-ray sensors, and their response increases with increasing X-ray generator voltage. The fabricated composite membranes exhibit semiconducting properties, easy to fabricate, low cost, and qualify practical device utilization in the X-ray dosimetry sector. • Composite membranes of polymer-nanoparticles were are synthesized • The membranes comprise of PVA, glycerol, and Tl 2 O 3 nanoparticles. • The nanoparticles were synthesized using a sol-gel modified method • Electrical characterization demonstrated that as nanoparticle concentration increases, the activation energy increase. • The membranes are suitable for potential applications in x-ray dosimetry field. [ABSTRACT FROM AUTHOR]

The rising requirement for radiation detection materials for practical applications has inspired to burgeoning investigation of scintillator materials. High performance X-ray detection require high spatial resolution and long-term stability, particularly for targeted objects at extreme conditions. Here, the CaF 2 :Eu2+ glass ceramic (GC), in which the CaF 2 :Eu2+ nanoparticles are wrapped by the glassy matrix, is successfully obtained the melting method. The as-obtained CaF 2 :Eu2+ GC manifests bright blue radioluminescence (RL) emission peaked at 470 nm thanks to the effective 5d-4f transition of Eu2+ ions. In addition, the as-obtained CaF 2 :Eu2+ GC presents high transmittance of 84.2% and visible light, contributing an excellent spatial resolution of 15 lp/mm at room temperature. Importantly, the as-obtained CaF 2 :Eu2+ GC exhibits high robustness at water conditions and high thermal stability with X-ray resolution of 12.1 lp/mm at 473 K. Our work demonstrates that CaF 2 :Eu2+ GC scintillators provide an excellent visualization tool for high-resolution scintillators X-ray images in harsh conditions. • The reduction efficiency of Eu2+ is significantly improved by mixing the reducing agent with glass ceramic raw and sintering. • The CaF 2 :Eu2+ glass ceramic is successfully obtained by melt-quenching method. • Multiple characterization prove that Eu2+, the luminescent center of glass ceramic, is greatly reduced in glass ceramic. • The strategy significantly reduces the light scattering and enhance the stability of the emitting centers. • The CaF 2 :Eu2+ glass ceramic for high resolution X-ray detection in harsh conditions. [ABSTRACT FROM AUTHOR]

• Adaptive grayscale image correction based on RAW prior knowledge is provided. • Adaptive power correction and compensation is provided. • Adaptive brightness and power correction based on HIS prior knowledge is provided. • An adaptive enhancement algorithm based on prior knowledge and HIS space. • The algorithm can achieve the best performance on various multi-modal data sets. • The best performance in the task of high grayscale infrared image target detection. Gray-scale images are widely used in many fields, including satellite remote sensing, autonomous driving, medical CT, and X-ray detection, but gray-scale images have many shortcomings, such as high bit, low contrast, and high dynamic ranges. The visual analysis of these images is complicated and limited by people's psychology and physiology, and pseudo-color technology is an effective way to solve this problem. To address the weak adaptive capability, poor robustness, and insufficient generalization of existing pseudo-color enhancement methods, an adaptive enhancement algorithm for high grayscale images based on prior knowledge and HIS space, called APKHHIS, was proposed. Firstly, an adaptive gray-scale image correction mapping algorithm based on original prior knowledge was designed, and the quantization of images with different bit depths is realized. Secondly, to ensure the effectiveness of the enhanced data, an adaptive power compensation method was designed to compensate for the brightness of the gray-scale corrected images. Finally, an adaptive brightness and power correction algorithm was innovatively designed for the first time, which can adaptively adjust the color saturation and spatial brightness of the image more reasonably. To verify the effectiveness of the algorithm proposed in this paper, adaptive enhancement experiments were carried out on multi-modal data sets. The subjective and objective experimental results show that the APKHHIS algorithm can achieve the best performance on various data sets, and has strong robustness and universality, which provides an effective solution for the adaptive enhancement of multi-modal low-quality images. [ABSTRACT FROM AUTHOR]

• A light weight CORONA-NET for diagnosing COVID-19 from chest X-ray images. • Deep feature extraction is performed by CNN, reduced yet strengthened by DWT. • The dataset included 3000 X-rays obtained locally through hospital in Denmark. • The method achieves excellent performance in comparison with the existing methods. • The proposed system has a 99.56 percent accuracy and 99.667 percent specificity. Since December 2019, COVID-19 has posed the most serious threat to living beings. With the advancement of vaccination programs around the globe, the need to quickly diagnose COVID-19 in general with little logistics is fore important. As a consequence, the fastest diagnostic option to stop COVID-19 from spreading, especially among senior patients, should be the development of an automated detection system. This study aims to provide a lightweight deep learning method that incorporates a convolutional neural network (CNN), discrete wavelet transform (DWT), and a long short-term memory (LSTM), called CORONA-NET for diagnosing COVID-19 from chest X-ray images. In this system, deep feature extraction is performed by CNN, the feature vector is reduced yet strengthened by DWT, and the extracted feature is detected by LSTM for prediction. The dataset included 3000 X-rays, 1000 of which were COVID-19 obtained locally. Within minutes of the test, the proposed test platform's prototype can accurately detect COVID-19 patients. The proposed method achieves state-of-the-art performance in comparison with the existing deep learning methods. We hope that the suggested method will hasten clinical diagnosis and may be used for patients in remote areas where clinical labs are not easily accessible due to a lack of resources, location, or other factors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Scintillator screen with micro/nano particles embedded into delignified wood. • Vertical column structured material suppressing the light lateral spreading. • Linear relationship between light yield and X-ray dose rate. • High spatial resolution X-ray imaging achieved. Nanocrystalline scintillators with low-cost, fast response, and high light yield are widely used for X-ray imaging. However, they fail in high-energy X-ray imaging because of the fundamental limitations due to lateral radiation spreading in thicker device-compatible active layers. This issue is resolved by using the novel nanocomposite containing CsPbBr 3 scintillation single-microcrystalites embedded into transparent, natural wood-derived light-guiding fibrous structures. The CsPbBr 3 crystals convert X-ray to visible photons with a high photoluminescence quantum efficiency (76 %), and an average fast photoluminescence decay time of 25.9 ns. The delignified wood-derived fiber-like lumina effectively guide light, while suppressing the lateral spreading of scintillation photons. This unique porous nanocomposite material offers an excellent X-ray detection performance, and linear response in a wide parameter range. The developed scintillator screen achieves well-resolved, high-contrast X-ray imaging, featuring a very high spatial resolution of 11.9 lp/mm at a modulation transfer function of 0.2, thus exceeding the benchmark industry standards and offering a new advanced materials platform for radiation detection and dosimetry applications. [ABSTRACT FROM AUTHOR]

Synergistic nanostructures possess enriched electrical and optical properties compared to conventional nanostructures. 1D - 3D synergized nanostructure was implied to elucidate the performance of the X-ray sensor for the first time. Current research in X-ray detection only focuses on implementing high attenuating material based on oxides/ perovskites in developing X-ray sensors. Herein we approached tailoring the performance of an X-ray sensor with a synergistic nanostructure composed of sodium vanadium oxide (NaV 3 O 8) with substantial grain boundary (GB) segregation of silver bismuth sulfide (AgBiS 2) , enabling the structured arrangement of nanostructured grains at the surface of NaV 3 O 8 nanorods. Then, it was coated as a thick film on top of the interdigitated electrodes by glass rod sliding technique to readout the dose-dependent X-ray sensing capability. From the X-ray impinged photocurrent characteristics, the sensor with 75 wt% AgBiS 2 segregated NaV 3 O 8 exhibits superior sensitivity 82.6 nC mGy−1 cm−2 and low-noise equivalent dose rate 1.04 mGy Hz−0.5 for 2.49 mGy s−1 than other compositions. These experimental findings explore the implication of synergistic nanostructures as active layers in direct conversion X-rays sensors for improved charge extraction and enhancement in X-ray impinged photocurrent at low dose rates. [Display omitted] • AgBiS 2 :NaV 3 O 8 segregated synergistic nanostructures with (100:0 wt%); (75:25 wt%); (50:50 wt%); (25:75 wt%) compositions was used to fabricate low-dose X-ray sensors. • X-ray impinged photocurrent characteristics reveal that X-ray sensors based on (25:75 wt%) NaV 3 O 8 : AgBiS 2 exhibit low dark current of 10-8A at 2 V bias condition. • Our device exhibit sensitivity of (82.6 nC mGy-1 cm-2) and NED (1.04 mGy Hz-0.5) at 2.49 mGy s-1 dose rate. [ABSTRACT FROM AUTHOR]

Hospital patients can have catheters and lines inserted during the course of their admission to give medicines for the treatment of medical issues, especially the central venous catheter (CVC). However, malposition of CVC will lead to many complications, even death. Clinicians always detect the malposition based on position detection of CVC tip via X-ray images. To reduce the workload of the clinicians and the percentage of malposition occurrence, we propose an automatic catheter tip detection framework based on a convolutional neural network (CNN). The proposed framework contains three essential components which are modified HRNet, segmentation supervision module, and deconvolution module. The modified HRNet can retain high-resolution features from start to end, ensuring the maintenance of precise information from the X-ray images. The segmentation supervision module can alleviate the presence of other line-like structures such as the skeleton as well as other tubes and catheters used for treatment. In addition, the deconvolution module can further increase the feature resolution on the top of the highest-resolution feature maps in the modified HRNet to get a higher-resolution heatmap of the catheter tip. A public CVC Dataset is utilized to evaluate the performance of the proposed framework. The results show that the proposed algorithm offering a mean Pixel Error of 4.11 outperforms three comparative methods (Ma's method, SRPE method, and LCM method). It is demonstrated to be a promising solution to precisely detect the tip position of the catheter in X-ray images. • An automatic catheter tip detection framework based on X-ray images is proposed. • The high-resolution features are maintained from start to end for tip detection. • The intermediate outputs show the catheter and the potential positions for the tip. • The framework shows the potential of machine Explainability. [ABSTRACT FROM AUTHOR]

Scintillators are used as radiation detectors because they absorb ionizing radiation and release energy as light. Inorganic glasses have significant advantages over inorganic crystals owing to their ease of fabrication, low cost, controllable shape, and thermal and chemical durability. However, large performance gaps, such as light yield and density, still exist between inorganic glasses and commercial inorganic crystals. Here, we present a demonstration of an inorganic scintillator based on phosphate glass with an alkali metal as the host and Ce3+ as the emission centers. This glass exhibits a high light yield of 2500 photons/MeV, which is higher than that of previously reported inorganic glass scintillators (approximately 2000 photons/MeV). The glass is transparent and has a fast decay time of approximately 30 ns, which is attributed to the 5d–4f optical transition of Ce3+, facilitating applications for inorganic glass scintillators for gamma- and X-ray detection. Furthermore, we investigated the difference in the energy-transfer efficiency of the fabricated inorganic glasses by changing the alkali metals. The energy transfer efficiency increases with an increase in the atomic number of the alkali metals; the thermoluminescence (TL) intensity decreases with an increase in the atomic number of the alkali metals. These results suggest that Cs is an optimum alkali metal to achieve a high light yield on phosphate glass scintillators, and they may be related to the difference in the number of electron–hole pairs that do not contribute to scintillation. • We fabricated a phosphate glass doped Ce3+ for gamma- and X-ray detection. • The fabricated glass scintillator exhibited a high light yield of 2500 photons/MeV. • Cs was an optimal alkali metal to achieve a high light yield. [ABSTRACT FROM AUTHOR]

A series of UVA-emitting LaB 3 O 6 :Ce3+ phosphors and La 0.96 Ce 0.04 B 3 O 6 /PMMA films were prepared. The calcining temperature, activator concentration and PL test temperature were studied for the luminescence properties of the phosphor. And the effect of phosphor content on transmittance and X-ray radiation capacity of the composite films was also studied. The results show that LaB 3 O 6 :Ce3+ emits continuous double peaks at 358 nm and 380 nm when excited at 333 nm, the fluorescence lifetime is about 10 ns, and the luminescence intensity at 150 °C is 73.71% of that at room temperature, which can be used as phosphors for UV phototherapy applications. Under X-ray excitation, the integrated intensity of the La 0.96 Ce 0.04 B 3 O 6 /PMMA composite film has a good linear relationship with the X-ray tube current and tube voltage, and the X-ray imaging of a car key taken by La 0.96 Ce 0.04 B 3 O 6 /PMMA composite film has good signal-to-noise ratio, which can be used for X-ray detection and imaging. • A UVA phosphor with good thermal stability can be applied to UV phototherapy. • LaB 3 O 6 :Ce3+ phosphor has no significant afterglow and can be used as scintillator material. • La 0.96 Ce 0.04 B 3 O 6 /PMMA composite film with good X-ray radiation capability can be used for X-ray detection and imaging. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a focused detection system for X-ray pulsar-based Navigation (XNAV) is designed based on Silicon Drift Detector (SDD). The detector electronics mainly adopts the digital trapezoidal shaping method to measure the Times-Of-Arrival (TOAs) and energy of photons. The time measurement accuracy is better than 500ns. The energy resolution is 191eV at 8.05keV, and the maximum count rate is 500kcps between 1 and 12keV. In the semi-physical simulation experiment, the filtering of noise photons by energy discrimination significantly improves the correlation degree between the cumulative pulse profile and the standard profile. [ABSTRACT FROM AUTHOR]

Abstract High Energy Photon Source (HEPS) with a beam energy of 6 GeV and emittance less than 1.0 nm rad will be constructed in China, which can provide high-brightness hard X-ray in the order of 1022 (phs/s/mm2/mr2/0.1%B.W.). The broadband and high-brightness monochromatic beam flux and white beam flux need new detector other than the ion chambers for measurement in case of saturation under high-flux conditions. The Diamond X-ray detector for the beam position monitoring and high brightness X-ray detection is developing for High Energy Photon Source in China. The diamond detector has advantages over other detector materials: a low atomic number resulting in a low absorption cross-section when used as beam position monitor and a high radiation and wide linear range when used as beam intensity measuring. In this paper, the polycrystalline chemical-vapour-deposition diamond detectors with an aluminium contact have been tested at 1W2B beamline at Beijing Synchrotron Radiation Facility (BSRF). A transmission-mode diamond X-ray detector is designed to simultaneously measure the X-ray flux, beam position in real time. [ABSTRACT FROM AUTHOR]

Abstract Materials that may show photochromism under X-rays have higher spatial resolution for visual low-energy X-rays detection over the commercial instruments and greater X-ray sensitivity than silver salt-based radiographic films. In this work, we discovered that the known MOF, [Zn(OOCH) 2 (Bpy)] n (Bpy = 4,4′-bipyridine), showed rare photochromic behaviour upon irradiation of hard and soft X-rays at room temperature. Graphical abstract Rare X-ray-induced photochromism at room temperature, with potential application for X-ray detection, was observed for a known MOF. Image 1 Highlights • Rare X-ray-induced photochromism at room temperature was observed for a known MOF built by non-photochromic ligands. • The mechanism of the X-ray-induced photochromic has been studied. • The MOF shows a potential application on X-ray detection. [ABSTRACT FROM AUTHOR]

Abstract We examined the use of cerium-doped gadolinium aluminum gallium garnet (GAGG:Ce) as a material for scintillation screens in synchrotron X-ray radiography (SXR). Highlighted for gamma-ray detection, GAGG:Ce is also an attractive material for SXR because of its high X-ray stopping power and the high light yield at around 530 nm. A thin and transparent screen prepared from our grown ingot of GAGG:Ce was compared with commonly used scintillators of CdWO 4 and YAG:Ce in terms of image quality under monochromatic X-ray illumination. Micron spatial resolutions were achieved with comparable image quality, suggesting that a single crystal of GAGG:Ce is competent scintillation material for SXR. Highlights • Micron-spatial resolutions are achievable using GAGG:Ce single crystal scintillation. • Visibility was compared with other commonly used scintillator screens. • GAGG:Ce was also competent in synchrotron X-ray micro computed tomography. [ABSTRACT FROM AUTHOR]

Abstract An ideal readout circuit would detect X-ray beam with full spectral information and Fano-limited precision and would deal with high count rates, limited only by charge transport within the detector. Unfortunately in a real readout IC in particular the performance in speed and noise are conflicting requirements. In this review the speed–noise trade-off is discussed, referring to the recent ICs for hybrid detectors: those with best results in the energy resolution and those with the highest counting rates. ICs demonstrating the best performance from each end and also intermediate solutions are analysed. [ABSTRACT FROM AUTHOR]

Abstract Standard methods used for establishing EDX Si(Li) detectors response functions (DRF) are tedious and require a significant amount of work and beam time, which is not always available. That fact frequently leads to the disregard of the specific DRF at the time of the measurement, and to the fit of spectra using "general" response functions, which were determined on detectors with different characteristics. The accurate description of the low energy side asymmetry of the peaks is necessary to quantify trace elements accurately and to determine fundamental parameters like X-ray intensity ratios and ionization cross sections. In the present work, a simple method to monitor the energy dependence of EDX detectors response function in the 5 keV to 15 keV range is presented. Four PIXE generated X-ray spectra of thin mono-elemental (Ti, Fe, Ni, and Au) films are shown to be enough for this purpose. The methodology can be used as a laboratory-based protocol to establish the DRF and to monitor it over time. [ABSTRACT FROM AUTHOR]

Abstract Laser induced transient current technique (LI-TCT) was proven to be a successful tool for measuring at the same time carrier lifetime, carrier mobility, and electric field distribution in X- and gamma ray detectors with plain contacts on opposite surfaces. Unfortunately, the most performing detectors exploit more complicated contact geometries that, hindering hole contribution to signal formation, allow a much better spectroscopy. In this paper, a LI-TCT based method is presented, for the determination of transport parameters as well as electric field distribution directly in single carrier devices. The method's validity is demonstrated in twin CdZnTe detectors having similar material properties, but different weighting potentials. [ABSTRACT FROM AUTHOR]

The influence of line-broadening and zero shift of the sensor on identifying spectral lines was eliminated by an improved K-medoids clustering algorithm after performing principal component analysis on the spectral band of interest. The intensity ratio of the acquired spectral lines was calculated and dealt with by empirical mode decomposition to predict the existence of porosity based on the method given by our previous study. Furthermore, the effect of sheet gap on porosity formation was investigated by the proposed method. The analysis results were verified by X-ray detection, which demonstrated the distribution of porosity as well. The results showed that an appropriate gap could contribute significantly to reducing the porosity. The spectral sensor system and analysis method proposed in this study may help decrease the testing costs and increase productivity, while maintaining high weld quality. [ABSTRACT FROM AUTHOR]

In-vitro dose response curves were built with 6 MV X-ray for a dose range of 0.1–6 Gy, at a dose rate of 300 cGy/min, using Linear Accelerator (LINAC, SIMENS PRIMUS) for Cytokinesis-Block Micronucleus (CBMN) and Dicentric Chromosome Aberration assay (DCA). The dose response curves constructed up to 6 Gy and also up to 4 Gy using the manual method were compared to those curves obtained with the software program such as CABAS (V.2) and Dose Estimate software (V.5.2). The alpha and beta coefficients for MN and CA obtained for the curves constructed up to 6 Gy showed variation compared to those obtained in dose response curve constructed up to 4 Gy. However, the doses estimated based on these coefficients did not show much variation. The results are discussed in this paper. [ABSTRACT FROM AUTHOR]

Multi energy X-ray sensors are able to differentiate and quantify X-rays of different energies. In contrast to conventional sensors, which simply record the overall energy of the X-rays whatever the energy of x-rays is, multi energy sensors provides a spectrum of the X-rays energies, which may be differently attenuated. In this study, the feasibility of this technology to detect changes in dry-cured ham slices after inducing proteolysis was evaluated. Effect of salt and water contents on the attenuation was also studied. In addition, the classification of commercial samples according to their proteolysis index was assessed. Results showed a decrease of attenuation for increasing proteolysis induction times (p < 0.01) for all the regions of the spectrum (energy bands), but not with the same intensity, at any of the analysed acquisition conditions. Salt and water contents produced a significant (p < 0.01) effect on the attenuation. Influence of salt content was higher than that of water content, and both affected the prediction of the proteolysis index. Classification score of commercial samples exhibited a limited discrimination capacity, showing the need for more sophisticated data analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two semiconductive Ba(II)-based CPs 1 and 2 with small exciton binding energy (E b) values were successfully prepared. • The 2 -based film detector achieves superior direct X-ray detection performance among CP-based detectors. • The enhanced π-π interactions are beneficial to exciton separation and charge carrier transport irradiated by X-ray. High-performance and low-cost X-ray detector is crucial for medical imaging, nondestructive industrial detection and security checks. Semiconductive coordination polymers (CPs) with designable structures, tunable property and high cost-effectiveness have recently emerged as promising materials in direct X-ray detection. However, due to the strong Coulomb interactions between photogenerated electrons and holes, most of CPs often exhibit high exciton binding energies, resulting in relatively insufficient exciton dissociation as well as low photocurrent output and detection sensitivity in turn. Here, we employed the anthracene-based ligand to obtain two semiconductive CPs, {[Ba 2 (Hadba) 4 (DMF) 8 ]·DMF} n 1 (H 2 adba = 4,4′-(9,10-anthracenediyl)dibenzoic acid, DMF = N , N -dimethylformamide) and [Ba(Hadba) 2 (DMA) 4 ] n 2 (DMA = N , N -dimethylacetamide). Both of them can effectively convert X-ray into electrical signals. Compared with compound 1 , compound 2 has a reduced E b (44.9 meV) caused by the reinforced π-π interactions, contributing to the facilitated carrier transport, a significant enhance in mobility-lifetime product (μτ) and detection sensitivity irradiated by X-ray. Based on the optimized detection performance, we prepared a flexible 2 -based composite film detector with a low detection of 1.02 μGy/s that meets the standard for medical imaging. In particular, this film-based detector achieves a high sensitivity of 137.31 μCGy−1 cm−2 and μτ product of 3.03 × 10−3 cm2 V−1, which are superior to all previously reported CP-based detectors and much higher than commercial α -Se. Simultaneously, a 5 × 5 pixelated X-ray imaging device was further constructed to show its potential application in direct X-ray detection and imaging. [ABSTRACT FROM AUTHOR]

Silicon drift detectors (SDDs) are widely applied for x-ray detection due to their remarkable energy resolution. The main contribution to energy resolution is the electrical noise of the measurement system. In addition, imperfect charge collection and ballistic deficits also deteriorate the energy resolution, which is closely related to bias conditions. However, bias condition's effect on energy resolution has been rarely reported. To investigate its effect on energy resolution, we proposed a quasi-double-sided silicon drift detector (QD-SDD) with a drift ring structure designed on the back side. QD-SDDs was simulated and verified to have more flexibility in bias conditions, achieving better electron collection efficiency and shorter collection time at higher bias voltages. Finally, the fabricated QD-SDDs were characterized using a55Fe radioactive source. The experimental results show that the energy resolution of the QD-SDD varies with different bias conditions. The optimal energy resolution is 170 eV under the optimized bias conditions. [ABSTRACT FROM AUTHOR]

The Gd 2 O 3 –La 2 O 3 –ZnO–B 2 O 3 –Eu 2 O 3 glasses with different Gd 2 O 3 concentration (Gd:LaZnBEu) were studied in the physical, structural, optical and luminescence properties. The density and refractive index of glass increased with addition of Gd 2 O 3 content. The FTIR spectra demonstrated the BO 3 and BO 4 borate complexes as the main construction in glass those were more disturbed by Gd 2 O 3 increasing. The BO 4 /BO 3 and bridging/non-bridging oxygen ratio, observed from XPS, changed by following the Gd 2 O 3 concentration whose 10 mol% owned the highest values of both ratios. In the absorption spectra, glasses absorbed some photons in UV – NIR region. The excitation by O2−→Eu3+ charge transfer (240 nm), Gd3+→Eu3+ energy transfer (275 nm) and direct Eu3+ excitation (394 nm) caused the strongest Eu3+ photoluminescence at 613 nm (5D 0 →7F 2). The glass with 5 mol%-Gd 2 O 3 , that possessed the optimum Eu3+ local site, exhibited the highest absorbance and photo-/radio-luminescence intensity. The CIE 1931 and UV lamp excitation revealed the strong reddish-orange emission of glasses. The photoluminescence decay time of Eu3+ in glasses were between 1.6 and 2.1 ms and decreased with added Gd 2 O 3 amount. The Gd:LaZnBEu glasses have a potential for LED, laser, display, and X-ray detection devices with integration mode. • The strong luminescence of Eu3+ under different excitations on Eu3+, Gd3+ and charge transfer. • High absorbance and luminescence intensity by the optimum BO 4 /BO 3 and BOs/NBOs ratio in glass. • The strong reddish-orange emission for LED, laser, display and X-ray detection applications. [ABSTRACT FROM AUTHOR]

We developed a two-stage microfluidic reactor consisting of one hot and one cold region to systematically investigate a radiolytic method to synthesize colloidal silver and to improve the sensitivity of radiation dosimeters based on the Ag nanoparticles plasmon intensity. The microfluidic approach avoided growth during the heating stage, resulting in the total absence of a plasmon band for non-irradiated samples, greater control of the particle size distribution, and decreased minimal detectable dose. Doses as low as 0.2 Gy could be detected with sensitivities higher than the reported in the literature. This is a great achievement once most chemical dosimeters, besides 3D gels, are not sensitive to such low doses. Samples prepared in the microreactor and exposed to doses from 0 to 0.75 Gy presented an unexpected absorption band above 500 nm and a fluorescence emission around 380 nm, evidencing the presence of Ag nanoclusters (AgNCs). Both, absorption and emission bands from AgNCs, increase in the 0-0.75 Gy range, suggesting that nucleation predominates in the microreaction stage and in the radiolytic step for doses below 1 Gy. Decreased fluorescence intensity and undetected absorption above 500 nm indicate that growth prevails for doses ≥ 1 Gy. Thus, our work presents a novel way to measure doses based on silver nanoclusters, including both absorption and emission as dosimetric parameters. Besides unveiling nucleation and growth mechanisms associated to nano clusters and particles formation in this radiolytic microreaction, the results put the spotlight on new possibilities for enhanced radiation detection employing AgNCs. [Display omitted] • Two-stage microfluidic reactor leads to decreased minimal detectable dose. • Microreaction results in silver nanoclusters (AgNCs) or nanoparticles (AgNPs). • Ag nanoclusters are formed for irradiation with doses below 0.75 Gy. • Doses as low as 0.2 Gy can be detected with both AgNPs and AgNCs. • AgNPs and AgNCs constitute a new multimodality platform for x-ray detection. [ABSTRACT FROM AUTHOR]

• X-ray-responsive PNIPAm-based microgels are obtained. • Diselenide/ditelluride crosslinkers are synthesized. • PNIPAm microgel-based interferometers are generated. • Interferometers can respond to 0–50 Gy X-rays with tunable colors. • Interferometers show ultrahigh sensitivity of 101.63 nm/Gy. We report the successful development of novel microgel-based interferometers for X-ray dose sensing, which can meet fast-developing and widespread applications of ionizing radiation. Poly(N-isopropylacrylamide) (pNIPAm)-based microgels are crosslinked by different molecules (i.e., N, N'-methylenebisacrylamide (BIS), N, N'-bis(acryloyl)cystamine (BAC), bis(2-acrylamidoethyl) diselenide (BASe), and bis(2-acrylamidoethyl) ditelluride) (BATe). These color-tunable photonic materials are generated by sandwiching X-ray-responsive microgels between two Au layers. The radiolysis of an aqueous solution by X-ray irradiation yields •OH radicals, leading to the cleavage of crosslinkers of pNIPAm-based microgels. The chemical reaction induces the swelling of microgels, increasing the distance between the two Au layers of the interferometers. Eventually, the optical signal of the device (i.e., reflectance spectra and color) varies with the X-ray dose, showing an ultrahigh sensitivity of 101.63 nm/Gy. For the first time, our work provides novel microgel-based interferometers for spectral and visual X-ray dose detection via the chemical–mechanical-optical signal transduction strategy. [ABSTRACT FROM AUTHOR]

Nanocrystalline materials have garnered significant recognition in the scientific and research community for developing X-ray sensors. The applicability of bismuth-based binary and ternary compounds has been extensively studied in X-ray imaging and cancer therapy applications owing to their high attenuation. Among the binary and ternary compounds of bismuth, the n-type semiconductor silver bismuth sulfide (AgBiS 2) was studied for the detection of X-rays at lower doses, based on its total attenuation (μ = 3.07 cm2 g−1 at 70 keV), density (ρ = 7.02 g cm−3), and bandgap (E g = 1.21 eV). The effect of grain size on X-ray sensing performance was examined to validate the effective size required for maximum attenuation of X-rays and successful extraction of induced mobility carriers. X-ray sensors with four different AgBiS 2 grain sizes were cast on interdigitated electrodes (IDEs) and subjected to different doses of X-rays at 2 V bias to study its dose-dependent X-ray sensing nature using an intra-oral (70 kVp-AC) X-ray machine. AgBiS 2 -based X-ray sensor exhibited the highest sensitivity of 20.13 μC mGy−1 cm−3 with the lowest Noise-equivalent dose ratio (NED) of 0.08 μGy Hz−0.5, 0.20 mGy detection limit and a response time of 0.12 s. This outcome validates that AgBiS 2 can be applied as a potential replacement for perovskites in direct X-ray detection. [Display omitted] • Grain size effect on nano AgBiS 2 was studied for direct conversion X-ray detection at 70 keV X-ray photon energy. • As-prepared AgBiS 2 was heat treated at 150 °C for 15, 60, 90, and 180 min to study the grain size effect. • AgBiS 2 with 54 nm size exhibits superior sensitivity (20.13 μC mGy−1 cm−3), NED (5 μGy Hz−0.5) and swift response (0.12 s) for 7.97 mGy dose. [ABSTRACT FROM AUTHOR]

In recent years, scientific CMOS (sCMOS) sensors have been vigorously developed and have outperformed CCDs in several aspects: higher readout frame rate, higher radiation tolerance, and higher working temperature. For silicon image sensors, image lag will occur when the charges of an event are not fully transferred inside pixels. It can degrade the image quality for optical imaging, and deteriorate the energy resolution for X-ray spectroscopy. In this work, the image lag of a sCMOS sensor is studied. To measure the image lag under low-light illumination, we constructed a new method to extract the image lag from X-ray photons. The image lag of a customized X-ray sCMOS sensor GSENSE1516BSI is measured, and its influence on X-ray performance is evaluated. The result shows that the image lag of this sensor exists only in the immediately subsequent frame and is always less than 0.05% for different incident photon energies and under different experimental conditions. The residual charge is smaller than 0. 5 e − with the highest incident photon charge around 8 ke − . Compared to the readout noise level around 3 e − , the image lag of this sensor is too small to have a significant impact on the imaging quality and the energy resolution. The image lag shows a positive correlation with the incident photon energy and a negative correlation with the temperature. However, it has no dependence on the gain setting and the integration time. These relations can be explained qualitatively by the non-ideal potential structure inside the pixels. This method can also be applied to the study of image lag for other kinds of imaging sensors. [ABSTRACT FROM AUTHOR]

Gaseous polarimetry applies in soft X-ray polarization detection, typically like the Gas Pixel detector (GPD) and the micropattern time projection chamber (TPC). The polarization phase angles resolve from photoelectron track trajectories for both of them. The photoelectron track images derived from read-out pixels or strips are the key to determining the performance of the polarimetry. Gaseous X-ray polarimetry is regularly optimized and diagnosed by the Geant4 associated with Garfield++ and finite element analysis software (full simulation). Although the results are more realistic by the full simulation, the sample generation is low efficiency, especially for large gain values of the multiplier stage. The 2-D photoelectron track images regularly generate by a gaussian smear of initial ionization electrons at present. However, discrepancies exist in the modulation curves, resulting in fuzzy diagnoses and optimization of polarimetry. In this study, a fast simulation framework is constructed, the reconstruction of polarization phase angles and energy spectrum of the samples obtained from the fast simulation are consistent with those from experiments and the full simulation, and the deviation of modulation factor is within 2% for both situations of the GPD and TPC. In addition, the fast simulation greatly improves the sample generation efficiency. These results illustrate the fast simulation model is relative accuracy and high efficiency, which provides a useful tool for gaseous X-ray polarimetry. [ABSTRACT FROM AUTHOR]

An 8-pixel X-ray diamond detector prototype, fabricated on an alumina substrate and specifically designed to operate at high temperature, has been developed and tested. Tungsten electrodes were developed as metal-semiconductor contact and showed an ohmic behavior, as inferred from current-voltage measurements. A 40-cycles thermal stress test performed in helium atmosphere, in which temperature has been varied cyclically between 100 and 240 °C, showed minor evolution of the detector dark current, presumably related to progressive water desorption from the alumina substrate. Conversely, X-ray photocurrent measurements showed no significant differences before and after the thermal cycles, confirming no degradation of the stability of the prototype even after prolonged operation at high temperature. [Display omitted] • A diamond X-ray detector prototype has been tested at high temperature (~240 °C). • Thermal tests (T = 100÷240 °C) in helium showed minor evolution of the dark current. • Photocurrent measurements confirm no loss in terms of X-ray detection. [ABSTRACT FROM AUTHOR]

X-ray detectors have drawn great attention due to their wide applications in medical imaging and industrial inspection. Lead halide perovskite exhibits excellent X-ray detection merits because of its high-Z element and outstanding photoelectric properties. However, the perovskite-based X-ray detectors exhibit poor stability, low resistivity and large dark leakage current due to the soft lattice and ion migration of perovskite materials. Herein, we used Ga 2 O 3 compact layer to form a heterojunction structure with formamidinum lead iodide (FAPbI 3) to largely ease these issues. Compared with the bare FAPbI 3 detector, the dark current of the FAPbI 3 /Ga 2 O 3 heterojunction detector is reduced by 3 orders of magnitude and the photo-to-dark current ratio (PDCR) increased by 31-fold. The detection limit of 0.23 mGys−1 is obtained which is 20 times lower than the FAPbI 3 detector and short response time of 20 ms is obtained. More importantly, the FAPbI 3 /Ga 2 O 3 device exhibits better repeatability due to the suppression of ion migration by Ga 2 O 3. This work provides an effective strategy to obtain low dark current and stable perovskite-based photodetector. • A coplanar interdigital MSM-structured X-ray detector was fabricated based on FAPbI 3 /Ga 2 O 3 heterojunction. • Low dark current density (4.1 pAmm−2), high PDCR (433) and low detection limit (0.23 mGys−1) were obtained. • The performance improvement of the device is due to the suppression of iodine ions migration by compact Ga 2 O 3. [ABSTRACT FROM AUTHOR]

Landmark detection has been well developed by deep learning methods, and the cascade-connected neural network (CCNN) stands out as a widely used deep learning landmark detection method. CCNNs consist of several stacked network backbones, where the predictions of the previous network backbone are used as the input of the following one. Due to GPU memory bottlenecks, CCNNs have two limitations. First, the network backbones of CCNNs have limited numbers and depths; thus, the learning ability of CCNNs is limited. Second, CCNNs are usually trained in low-resolution images. However, the neighboring pixels in high-resolution images are usually vital for landmark detection, especially for cephalometric landmark detection. This paper interprets CCNNs as the discrete approximation of ordinary differential equations. Relying on this explanation, we further propose a novel model, called the cascade-refine model , which takes advantage of CCNNs and makes it possible to overcome the limitations of number and depth by sharing parameters among stacked network backbones. Moreover, the proposed model obeys the rule of coarse-to-fine architectures, where a global module is used to generate the coarse landmark locations, and a local module is adopted to tune the pixel error of latent landmark locations in the region of interest. The proposed model is trained in an end-to-end manner. Thus, the neighboring detailed high-resolution pixels are directly exploited for cephalometric landmark detection. The proposed cascade-refine model outperforms state-of-the-art methods on the public Automatic Cephalometric X-ray Landmark Detection Challenge 2015 dataset. We also built two private cephalometric X-ray datasets, and experimental results on both datasets demonstrate the good performance of the proposed model. • A cascade training strategy was introduced to model the discrete approximation of an ODE. • The proposed cascade-refine model can continually refine landmark locations. • The cascade-refine model breaks through the limitation of GPU memory. • The landmark label map was proposed to the local module of the cascade-refine model. [ABSTRACT FROM AUTHOR]

Semiconductor sensors based on the rad-optic effect enable ultra-fast detection of X-rays and play an important role in fusion diagnostics. Obtaining the responsivity of the semiconductor ultrafast response material is an important part of characterization. In this work, the refractive index change mechanism of the semiconductor under X-ray irradiation was analyzed, and the quantitative relationship between the diffraction efficiency and the X-ray photon energy was established through the LT-AlGaAs diffraction imaging experiments. The impulse responses of LT-AlGaAs under 1 keV–10 keV X-ray radiation were calculated, revealing the variation of responsivity with radiated photon energy. Imaging experiments of LT-AlGaAs were performed by bombarding an Al target to generate 1.5 keV X-rays. The diffraction images were obtained in agreement with the simulations. The responsivity of the semiconductor chip increases with the square of the incident X-ray power density. This study provides meaningful analyses for the development of ultra-fast X-ray imaging systems based on the rad-optic effect. [ABSTRACT FROM AUTHOR]