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Computerized disease detection systems (CDDs) have proven effective for automatic screening in recent years. Among the standard procedures in hospitals for faster and more accurate diagnosis is medical imaging-based disease screening. We aim to develop a CDD that detects COVID-19 using chest X-rays pre-trained vision transformers (PVTs). This scheme includes the following steps: (1) collecting images and resizing them, (2) implementing PVT for feature extraction, and (3) binary classifying the results and validating the proposed schemes. To prove the merit of the developed scheme, 4800 images (2400 normal and 2400 COVID-19) are analyzed. MLP classifiers verify the PVT performance using patch sizes of 6, 12, and 24. A patch size 24 results in 97.5% accuracy for the proposed CDD system. When patch sizes are increased to 12, accuracy increases to over 98%. For this specific task, smaller patch sizes are more effective. These high-accuracy results demonstrate the effectiveness of the developed scheme for detecting COVID-19 in chest X-rays. [ABSTRACT FROM AUTHOR]

To effectively solve the problems of low detection accuracy caused by low quality image discriminative features of X-ray weld defects, lack of intuitive representation of the defect size of existing detection algorithms, and the strong subjectivity of the detection model artificial parameter adjustment, an X-ray weld defect detection and size measurement algorithm based on neural network self-optimization is proposed. Firstly, a high-performance detection model for X-ray weld defects is constructed, and the detection accuracy is comprehensively improved through a series of featured module designs with the capabilities of feature information enhancement and multi-scale information fusion. Secondly, a model optimization strategy is proposed to obtain the optimal hyperparameter components of the model through adaptive optimization to enhance the model's self-learning capability. Finally, by constructing the mapping relationship between the actual size of defects and the screen resolution, the size measurement algorithm of weld defects is designed, and the integrated technology of defect detection and size measurement is realised. Experimental results show that the proposed algorithm achieves good results even on a small-scale X-ray weld seam defect dataset. Compared to other classical and advanced detection models used in the experiments, mAP@0.5 is improved by an average of 16.1% and mAP@.5:.95 by an average of 10.7%. The image processing speed reaches up to 68 frames per second, and the error between the size calibration and manual actual measurement is less than 0.1 cm, which can meet the real-time detection requirements for weld seam defects in practical industrial production. In this research, the specific contributions are as follows:: • We construct a high-performance X-ray weld defect detection model to improve the detection efficiency. • We propose an HCOA model self-optimization strategy for high-dimensional hyperparameter evolution of deep neural networks. • We design an algorithm to measure the sizes of welding defects which can provide support for defect grade assessment. • Our method compared with other models, mAP@0.5 is improved by an average of 16.1% and mAP@.5:.95 by an average of 10.7%. • The image processing speed reaches up to 68 frames per second, the size error is less than 0.1cm. [ABSTRACT FROM AUTHOR]

This study examines a perovskite-based graphene field effect transistor (P-GFET) device for X-ray detection. The device architecture consisted of a commercially available GFET-S20 chip, produced by Graphenea, with a layer of methylammonium lead iodide (MAPbI 3) perovskite spin coated onto the top of it. This device was exposed to the field of a molybdenum target X-ray tube with beam settings between 20 and 60 kVp (X-ray tube voltage) and 30–300 μA (X-ray tube current). Dose measurements were taken with an ion-chamber and thermo-luminescent dosimeters and used to determine the sensitivity of the device as a function of the X-ray tube voltage and current, as well as source-drain voltage. The X-ray tube was also simulated in this work with GEANT4 and MCNP to determine the dose rate and power incident on the device during irradiation. These simulations were then used to determine the responsivity as a function of the X-ray tube voltage and current, as well as the source-drain voltage. Overall, a strong positive correlation between sensitivity and source-drain voltage was found. Conversely, the sensitivity was found to decrease – roughly exponentially – as a function of both the X-ray tube current and energy. Similar trends were seen with responsivity. We report the models used for the study as well as address the feasibility of the device as a low-energy (<70 keV) X-ray photon detector. [Display omitted] • A perovskite-based graphene field effect transistor was examined under x-rays. • Charges in the perovskite and recirculating holes in the graphene provide gain. • Found decreasing responsivity with increasing x-ray intensity. • Buildup of charges at the junction limits charge transfer. [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]

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]

Flexible and stretchable materials are increasingly being investigated for future technological platforms, polymer based materials being the most suitable candidates for those emerging technologies. This work reports on polymer based scintillator composites based on the thermoplastic elastomer Styrene-Ethylene/Butadiene-Styrene (SEBS) and Gd 2 O 3 :Eu 3+ scintillator nanoparticles, to form a polymer-based flexible and stretchable material for X-ray indirect detectors. Further, visible light yield under X-ray irradiation was improved by the inclusion of 2,5 dipheniloxazol (PPO) and (1,4-bis (2-(5-phenioxazolil))-benzol (POPOP) within the polymer matrix. Together with high levels of stretchability, with deformations up to 100%, the films exhibit suitable performance with low mechanical hysteresis (less than 1.5 MJ/m 3 for cycles up to 100% of strain) and reproducibly such as a scintillator material for the conversion of X-ray radiation into visible radiation. The decrease of just ∼13% of the X-ray radiation into visible light upon stretching up to 100% is attributed to a reduction of the effective filler concentration and proves the suitability of the developed materials for large area and stretchable X-ray radiation detectors. [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]

In this article X-ray radiation sensitivity of ZnS thin film prepared by a chemical bath deposition technique has been reported. The films were prepared under 0.10, 0.15 and 0.20 molarity (M). Characterization reports show that the 0.20 M film has the best quality than the other low molarity films. I-V characteristics of the films were studied under dark condition and observed that the film prepared at 0.20 M has an electrical conductivity of 2.06×10 −6 (Ω cm) −1 which is about 10 times greater than the other lower molarity films. Further, the I-V characteristic of this film has studied under UV and X-ray radiations. The current under X-ray radiation is found to be significantly higher than that under the UV radiation. At a fix bias voltage of 1.0 V, the conductivity under UV radiation is found to be 3.26×10 −6 (Ω cm) −1 whereas that under the X-ray is 4.13×10 −5 (Ω cm) −1 . The sensitivity under X-ray radiation is significantly greater than that under the UV radiation. This analysis suggests that the ZnS thin film which is used as a UV radiation sensor can also be used as a potential X-ray radiation sensor. [ABSTRACT FROM AUTHOR]

AgI incorporated perovskite X-ray detectors were fabricated based on the spray-coating technique. The effect of AgI incorporation on the optoelectronic properties was systematically investigated. With suitable amount of AgI content, metal halide perovskite exhibited improved crystallinity, charge carrier mobility, lifetime, and X-ray sensitivity. [Display omitted] • Perovskite thick films were fabricated via spray-coating process. • The effect of AgI incorporation was carefully evaluated and optimized. • X-ray detectors based on the spray-coated perovskite thick junctions were fabricated. • High X-ray sensitivity, low detection limit and fast response were achieved. Metal halide perovskites have emerged as a promising candidate for ionizing radiation detection, thanks to the facile fabrication, excellent optoelectronic properties and high attenuation coefficient. In order to fully absorb the incident X-ray photons, X-ray detectors require relatively thick active layers. However, it is challenging to obtain thick perovskite films based on conventional solution-based techniques, due to the limited solubility and viscosity of the perovskite precursors. In this work, we introduced spray-coating to deposit perovskite films on various substrates, and achieved tunable and thick films. On the other hand, the charge transport is another issue limiting the device performance of perovskite X-ray detectors. Compared with conventional inorganic semiconductors, hybrid perovskites possess relatively poor charge carrier mobility and lifetime. To address this issue, we incorporate AgI within the perovskite precursor, and systematically investigated their optoelectronic properties. It was found that the optimized AgI incorporated perovskite films exhibited the highest mobility-lifetime product, resulted X-ray sensitivity up to 3433 μGy air −1 cm−2 and ultra-low detection limit of 3.5 nGy air s−1, suggesting great potential for X-ray detection. [ABSTRACT FROM AUTHOR]

Organometal halide perovskites have proven to be potential materials for X-ray detection due to their great photoelectric properties, high radiation attenuation and low-cost preparation. However, ion migration is one of the obstacles for its applications, especially, ion migration via surface is much easier in single crystal materials than bulk diffusion which could significantly degrade the device performances. In this paper, the KCl passivation layer is prepared by the thermal evaporation method and inserted between crystal and electrode The trap density and μ τ product of pristine and KCl passivated MAPbI 3 devices are compared, and the results demonstrate KCl as a passivation layer can effectively passivate the surface traps and improve electrical performance. The KCl passivated MAPbI 3 detector exhibits a high X-ray sensitivity of 3700 μ C Gy air − 1 cm −2 under −20 V bias. [ABSTRACT FROM AUTHOR]

The Astrophysics Division of CEA Saclay has a long history in the development of CdTe based pixelated detection planes for X and gamma-ray astronomy, with time-resolved imaging and spectrometric capabilities. The last generation, named Caliste HD, is an all-in-one modular instrument that fulfills requirements for space applications. Its full-custom front-end electronics is designed to work over a large energy range from 2 keV to 1 MeV with excellent spectroscopic performances, in particular between 10 and 100 keV (0.56 keV FWHM and 0.67 keV FWHM at 13.9 and 59.5 keV). In the frame of the ORIGAMIX project, a consortium based on research laboratories and industrials has been settled in order to develop a new generation of gamma camera. The aim is to develop a system based on the Caliste architecture for post-accidental interventions or homeland security, but integrating new properties (advanced spectrometry, hybrid working mode) and suitable for industry. A first prototype was designed and tested to acquire feedback for further developments. The main difference between astronomy and nuclear applications is the radiation flux and energy-ranges involved. In this study, we particularly focused on spectrometric performances with high energies and high fluxes. Therefore, our device was exposed to energies up to 700 keV ( 133 Ba, 137 Cs) and we measured the evolution of energy resolution (0.96 keV at 80 keV, 2.18 keV at 356 keV, 3.33 keV at 662 keV). Detection efficiency decreases after 150 keV, as Compton effect becomes dominant. However, CALISTE is also designed to handle multiple events, enabling Compton scattering reconstruction, which can drastically improve detection efficiencies and dynamic range for higher energies up to 1408 keV ( 22 Na, 60 Co, 152 Eu) within a 1-mm thick detector. In particular, such spectrometric performances obtained with 152 Eu and 60 Co were never measured before with this kind of detector. [ABSTRACT FROM AUTHOR]

In this article, a two-dimensional detector based on plasma display technology was investigated as a candidate for a flat-panel radiation detector. By using the three-dimensional Garfield code, the dependence of the electric field and multiplication on various electrode structures was examined. Based on the calculation of multiplication, three different electrode designs, including CAC, ridged CAC, and double-ridged CAC structures were selected and prototype detectors adopting these designs were fabricated and tested. The performance of these detectors was evaluated by measuring the charge density and sensitivity. The charge density of the double-ridged CAC detector during the X-ray for the on condition varied from 0.482 up to 2.59 μ C / cm 2 at the address bias scope of −500–−1500 V , while the cathode voltage was locked at - 400 V . The sensitivity of the same detector was 0.596 nC / mR ⋅ cm 2 in an electric field of 0.54 V/μm, which was the highest value. This was about one-third lower than the sensitivity of the amorphous selenium (a-Se) based detector at 10 V/μm. [ABSTRACT FROM AUTHOR]

Results characterizing the performance of prototype thin (3µm i layer) GaAs p+–i–n+ mesa photodiodes (one 200µm diameter and one 400µm diameter device) are presented showing the spectral performance of the devices at photon energies from 4.95keV (V Kα1 X-ray fluorescence) to 59.5keV (241Am γ-ray emission). The devices were operated uncooled at +33.3°C. The energy resolution (full width half maximum) was measured to vary from 780eV at 4.95keV to 950eV at 59.5keV for the 200µm diameter diode, and from 1.08keV at 4.95keV to 1.33keV at 59.5keV for the 400µm diameter diode. The increased broadening of FWHM with increasing photon energy was found to be greater than can be explained by the expected energy dependence of the Fano noise, but the peak charge output from the devices varied linearly (R 2 200 µm=0.99998, R 2 400 µm=0.999998) with incident photon energy. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we present the methods, results, and analysis of the BepiColombo SIXS instruments' ground calibrations. The aim of these calibrations was to characterize the performance of the three SIXS X-ray detectors to enable reliable spectral analysis of the solar X-ray data. The ground calibrations for characterizing the performance of the three separate HPSi (High-Purity Silicon) PIN (Positive Intrinsic Negative) X-ray detectors included the following tasks. Determination of the energy resolution as a function of photon energy at different operational temperatures, determination of the detector sensitivity within the FoV (Field of View) as a function of the off-axis and roll angles, pile-up tests for determining the speed of the read out electronics, measurements of the low energy threshold of the energy scale, i.e. the minimum measurable photon energy corresponding to the adjustable software parameter, a comparison calibration of the fluorescence line fluxes with the SMART-1 XSM FS (Flight Spare) detector, and determination of the shifting of the energy scale as a function of the ambient temperature. We also describe the method and results of determining the geometrical area of the detector apertures based on the image analysis of very high resolution photographs obtained with by the Scanning Electron Microscope (SEM). [Copyright &y& Elsevier]

The internal defects of the Aluminum Conductor Composite Core (ACCC) can be effectively visualized by X-ray imaging. However, the online detection of internal defects in the carbon core is challenging due to the huge data quantity and inconspicuous defects. In this paper, we propose an automatic defect detection framework for ACCC X-ray scans based on deep convolution neutral networks. The proposed method is based on an image classification network, with Inception-Resnet as backbone. Image normalization is conducted as the pre-processing step to reduce the training cost. We also propose a new data augmentation method according to the morphological character of the defect samples, to improve the extensiveness of the method. Experiment results have proven that the proposed method can effectively recognize the small and inconspicuous defects, with 3.5% improvement on mean Average Precision, compared to the object detection network (RetinaNet). Experiment also verifies the positive effect for data normalization and augmentation. [ABSTRACT FROM AUTHOR]

X-ray detection is an important technology for medical diagnosis as well as industrial and security inspections. While today's commercial X-ray detectors are bulky, photodetectors based on organic semiconductors have attracted increasing attention owing to their low temperature processing capabilities, flexibility and low cost. Nonetheless, the low X-ray attenuation coefficient of organic semiconductors still hinders their practical application. Herein, a new organic-inorganic hybrid strategy is proposed to improve the X-ray sensitivity of organic photodetectors (OPDs). A solution-processed X-ray sensitive hybrid OPD is fabricated by embedding CsPbBr 3 quantum dots (QDs) into a P3HT:PC 61 BM bulk heterojunction photodiode. The QDs, acting as embedded scintillators in the organic active layer, maintain a high radioluminescence. The proposed hybrid structure enables indirect X-ray detection in a comprehensive manner. These hybrid photodetectors exhibit suppressed dark current densities in the range of tens of picoamperes per square centimeters for different weight ratios of blended QDs. The best OPD achieves a sensitivity of 229.6 e nGy−1 mm−2 (3.67 μC Gy−1 cm−2) and a dark current of 23.3 pA cm−2 at a low operating voltage (−3 V) for 20–80 kV "soft" X-rays, thus representing great potential for the development of next generation low cost, portable, and highly sensitive X-ray detectors. [Display omitted] • An all-in-one X-ray photodetector is realized by embedding CsPbBr 3 QDs into the P3HT:PC 61 BM photodiode. • The hybrid photodetectors exhibit suppressed dark current densities and high photosensitivity. • Great enhancement in X-ray sensitivity is achieved with CsPbBr 3 QDs. [ABSTRACT FROM AUTHOR]

• Novel crushed perovskite crystal/polymer composite films were prepared by mechanical grinding and sieving processes. • X-ray detectors based on the perovskite/polymer composite films demonstrated excellent stability, low dark current and noise and fast response. • The as-prepared devices exhibited high X-ray sensitivity of ∼488 μC/(Gy air cm2) with lowest detectable X-ray dose rate of 2.3 μGy air /s. Organic-inorganic hybrid perovskite materials have attracted increasing attention in recent years for ionizing radiation detection due to their large cross-section for high energy X-ray or gamma ray, defect-tolerance, large mobility lifetime product, tunable bandgap and facile preparation of single crystals. However, the thickness of solution processed perovskite polycrystalline films are normally limited, and single crystals are fragile and hard to be utilized as a device. In this article, we successfully realized the preparation of the perovskite crystal/polymer composites, through a novel process involving mechanically grinding and sieving. X-ray detectors were fabricated based on the relatively thick composite films via solution process. The device performance under the irradiation of X-rays were also investigated, in terms of stability, dark current, noise and temporal response. Our devices exhibited remarkable performance metrics, which proved that the perovskite composite films can be used to fabricate highly efficient and low-cost X-ray detectors. [ABSTRACT FROM AUTHOR]

• A new deep learning method is proposed and applied to detect arm fractures in X-rays. • The proposed method achieves the state-of-the-art average precision (AP) in arm fracture detection. • Experienced radiologists are invited to annotate nearly 4000 arm fracture X-rays to evaluate our method. In this paper, a novel deep learning method is proposed and applied to fracture detection in arm bone X-rays. The main improvements include three aspects. First, a new backbone network is established based on feature pyramid architecture to gain more fractural information. Second, an image preprocessing procedure including opening operation and pixel value transformation is developed to enhance the contrast of original images. Third, the receptive field adjustment containing anchor scale reduction and tiny RoIs expansion is exploited to find more fractures. In the experiments, nearly 4000 arm fracture X-ray radiographs collected from MURA dataset are annotated by experienced radiologists. The experiment results show that the proposed deep learning method achieves the state-of-the-art AP in arm fracture detection and it has strong potential application in real clinical environments. [ABSTRACT FROM AUTHOR]