Two-Dimensional Perovskite Single Crystals for High-Performance X-ray Imaging and Exploring MeV X-ray Detection

Scintillation semiconductors play increasingly important medical diagnosis and industrial inspection roles.Recently,two-dimensional(2D)perovskites have been shown to be promising materials for medical X-ray imaging,but they are mostly used in low-energy(≤130 keV)regions.Direct detection of MeV X-rays,which ensure thorough penetration of the thick shell walls of containers,trucks,and aircraft,is also highly desired in practical industrial applications.Unfortunately,scintillation semiconductors for high-energy X-ray detection are currently scarce.Here,This paper reports a 2D(C_(4)H_(9)NH_(3))_(2)PbBr_(4)single crystal with outstanding sensitivity and stability toward X-ray radiation that provides an ultra-wide detectable X-ray range of between 8.20 nGy_(air)s^(-1)(50 keV)and 15.24 mGy_(air)s^(-1)(9 MeV).The(C_(4)H_(9)NH_(3))_(2)PbBr_(4)single-crystal detector with a vertical structure is used for high-performance X-ray imaging,delivering a good spatial resolution of 4.3 Ip mm^(-1)in a plane-scan imaging system.Low ionic migration in the 2D perovskite enables the vertical device to be operated with hundreds of keV to MeV X-ray radiation at high bias voltages,leading to a sensitivity of 46.90μC Gy_(air)-1 cm^(-2)(-1.16 Vμm^(-1))with 9 MeV X-ray radiation,demonstrating that 2D perovskites have enormous potential for high-energy industrial applications.

Lead-free molecular one-dimensional perovskite for efficient X-ray detection

In recent years,great progress has been achieved for organicinorganic halide perovskites due to their excellent optoelectronic properties and stability for photovoltaics,light emitting diodes,and high-energy radiation detection[1-5].One-dimensional(1D)perovskites,as an important derivative of three-dimensional(3D)perovskites,exhibit low exciton dissociation efficiency,which can produce strong quantum confinement and form self-trapping excited state[6],In addition,the hydrophobic properties and the inhibition of ion migration from large organic cations improve the moisture and thermal stability for optoelectronic devices.

Perovskite semiconductors for direct X-ray detection and imaging

Halide perovskites have emerged as the next generation of optoelectronic materials and their remarkable performances have been attractive in the fields of solar cells,light-emitting diodes,photodetectors,etc.In addition,halide perovskites have been reported as an attractive new class of X-ray direct detecting materials recently,owning to the strong X-ray stopping capacity,excellent carrier transport,high sensitivity,and cost-effective manufacturing.Meanwhile,perovskite based direct Xray imagers have been successfully demonstrated as well.In this review article,we firstly introduced some fundamental principles of direct X-ray detection and imaging,and summarized the advances of perovskite materials for these purposes and finally put forward some needful and feasible directions.

Ultrasensitive and stable X-ray detection using zero-dimensional lead-free perovskites

Sensitive and reliable X-ray detectors are essential for medical radiography,industrial inspection and security screening.Lowering the radiation dose allows reduced health risks and increased frequency and fidelity of diagnostic technologies for earlier detection of disease and its recurrence.Three-dimensional(3 D)organic-inorganic hybrid lead halide perovskites are promising for direct X-ray detection-they show improved sensitivity compared to conventional X-ray detectors.However,their high and unstable dark current,caused by ion migration and high dark carrier concentration in the 3 D hybrid perovskites,limits their performance and long-term operation stability.Here we report ultrasensitive,stable X-ray detectors made using zero-dimensional(0 D)methylammonium bismuth iodide perovskite(MA3Bi2I9)single crystals.The 0 D crystal structure leads to a high activation energy(Ea)for ion migration(0.46 e V)and is also accompanied by a low dark carrier concentration(~10^6 cm^-3).The X-ray detectors exhibit sensitivity of 10,620μC Gy-1 air cm-2,a limit of detection(Lo D)of 0.62 nG yairs-1,and stable operation even under high applied biases;no deterioration in detection performance was observed following sensing of an integrated X-ray irradiation dose of^23,800 m Gyair,equivalent to>200,000 times the dose required for a single commercial X-ray chest radiograph.Regulating the ion migration channels and decreasing the dark carrier concentration in perovskites provide routes for stable and ultrasensitive X-ray detectors.

A large-grain-size thick-film polycrystalline diamond detector for x-ray detection

A diamond film with a size of 6×6×0.5 mm^3 is fabricated by electron-assisted chemical vapor deposition. Raman spectrum analysis, x-ray diffraction and scanning electron microscope images confirm the high purity and large grain size, which is larger than 300 μm. Its resistivity is higher than 10^12 W· cm. Interlaced-finger electrodes are imprinted onto the diamond film to develop an x-ray detector. Ohmic contact is confirmed by checking the linearity of its current–voltage curve. The dark current is lower than 0.1 n A under an electric field of 30 k V cm^-1. The time response is 220 ps. The sensitivity is about 125 m A W^-1 under a biasing voltage of 100 V.A good linear radiation dose rate is also confirmed. This diamond detector is used to measure x-ray on a Z-pinch, which has a double-layer 'nested tungsten wire array'. The pronounced peaks in the measured waveform clearly characterize the x-ray bursts, which proves the performance of this diamond detector.

X-ray detection based on complementary metal-oxide-semiconductor sensors

Complementary metal-oxide-semiconductor(CMOS) sensors can convert X-rays into detectable signals; therefore, they are powerful tools in X-ray detection applications. Herein, we explore the physics behind X-ray detection performed using CMOS sensors. X-ray measurements were obtained using a simulated positioner based on a CMOS sensor, while the X-ray energy was modified by changing the voltage, current, and radiation time. A monitoring control unit collected video data of the detected X-rays. The video images were framed and filtered to detect the effective pixel points(radiation spots).The histograms of the images prove there is a linear relationship between the pixel points and X-ray energy. The relationships between the image pixel points, voltage, and current were quantified, and the resultant correlations were observed to obey some physical laws.

BACKGROUND RECTIFICATION AND FEATURE EXTRACTION OF IMAGE IN A SPOT WELD OF AL ALLOY X-RAY DETECTION

A primary study on Processing in X - ray inspection of spot weld for aluminum alloy spot welding,in- cluding for background simulation,acquisition of ideal binary image, and extraction and identifi- cation of defect features was presented.

X-ray detection of ingested non-metallic foreign bodies

AIM: To determine the utility of X-ray in identifying non-metallic foreign body(FB) and assess inter-radiologist agreement in identifying non-metal FB. METHODS: Focus groups of nurses, fellows, and attending physicians were conducted to determine commonly ingested objects suitable for inclusion. Twelve potentially ingested objects(clay, plastic bead, crayon, plastic ring, plastic army figure, glass bead, paperclip, drywall anchor, eraser, Lego?, plastic triangle toy, and barrette) were embedded in a gelatin slab placed on top of a water-equivalent phantom to simulate density of a child's abdomen. The items were selected due to wide availability and appropriate size for accidental pediatric ingestion. Plain radiography of the embedded FBs was obtained. Five experienced radiologists blinded to number and types of objects were asked to identify the FBs. The radiologist was first asked to count thenumber of items that were visible then to identify the shape of each item and describe it to a study investigator who recorded all responses. Overall inter-rater reliability was analyzed using percent agreement and κ coefficient. We calculated P value to assess the probability of error involved in accepting the κ value.RESULTS: Fourteen objects were radiographed including 12 original objects and 2 duplicates. The model's validity was supported by clear identification of a radiolucent paperclip as a positive control, and lack of identification of plastic beads(negative control) despite repeated inclusion. Each radiologist identified 7-9 of the 14 objects(mean 8, 67%). Six unique objects(50%) were identified by all radiologists and four unique objects(33%) were not identified by any radiologist(plastic bead, LegoTM, plastic triangle toy, and barrette). Identification of objects that were not present, false-positives, occurred 1-2 times per radiologist(mean 1.4). An additional 17% of unique objects were identified by less than half of the radiologists. Agreement between radiologists was considered almost perfect(kappa 0.86 ± 0.08, P < 0.0001).CONCLUSION: We demonstrate potential non-identification of commonly ingested non-metal FBs in children. A registry for radiographic visibility of ingested objects should be created to improve clinical decision-making.

Exploring centimeter-sized crystals of bismuth-iodide perovskite toward highly sensitive X-ray detection

Lead-halide perovskites exhibit outstanding performance in X-ray detection due to their intrinsic features such as high charge carrier mobility,large atomic number,and long carrier lifetime,but the toxicity of lead is regarded as the major factor hindering their development.Here,we introduce organic molecule(R)-(-)-2-methylpiperazine(R-MPz)into the bismuth-based structure to synthesize lead-free(R)-(H_(2)MPz)BiI_(5)(R-MBI).The high-quality centimeter-sized single crystals have been obtained,which show a low dark current and superior environmental stability.Particularly,the single-crystal device of R-MBI exhibits a highμτproduct up to 1.88×10^(-4)cm^(2)/V and a low trap density of 1.21×10^(10)cm^(-3).Further,the detector displays excellent detection sensitivity of 263.58μC Gy_(air)^(-1)cm^(-2)and a favorable low detection limit of 4.35μGyair/s,both of which meet the requirement for medical diagnostics.These findings shed light on the exploration of innovative bismuth-based hybrid perovskites for high-performance X-ray detection.

A stable radiochromic semiconductive viologen-based metal-organic framework for dual-mode direct X-ray detection

Direct X-ray detectors,which directly convert X-rays into electrical signals through semiconductors,have higher space solution than scintillator-mediated indirect X-ray ones and are high desirable for early cancer detection and other applications,but the mainstream commercialα-Se detector is still largely limited by high production costs,large leakage current and low stability.This article reports an easily prepared,stable radiochromic semiconductive metal–organic framework(MOF),(MV)[Cd_(3)(tdc)_(4)]·2H_(2)O(RCS-1,H_(2)tdc=2,5-thiophenedicarboxylic acid;MV^(2+)=methyl viologen cation)with direct X-ray detecting ability.With a large bulk resistivity of 8.40×10^(9)Ωcm,this material ensures minimal dark current and low noise for X-ray detection.Additionally,it exhibits higher sensitivity to W KαX-rays(98.58μC Gy^(-1)cm^(-2))thanα-Se(~20μC Gy^(-1)cm^(-2)).Meanwhile,unlike most reported direct X-ray detecting semiconductors,compound RCS-1 shows remarkable color change upon X-ray irradiation owing to the presence of photochromism-active viologen cations.This feature offers an appealing visual detecting ability to direct X-ray detectors that provide only the electrical signals.

Expanding the toolbox of metal-free organic halide perovskite for X-ray detection

X-ray detection plays a crucial role across various aspects of our daily lives,encompassing medical diagnoses,security screenings,and non-destructive examinations in industrial settings.Given the wide array of application contexts,a wealth of opportunities is entailed with the practical utilization of both organic and inorganic X-ray detection materials.A novel and promising contender in this realm is the emergence of metal-free organic halide perovskites(O-PVSKs),offering great opportunities and tremendous potential in X-ray detection.This potential can be attributed to the distinct crystalline configuration of O-PVSKs,where organic constituents are structured into an ABX3perovskite arrangement.Consequently,O-PVSKs exhibit captivating characteristics reminiscent of organic materials,such as lightweight nature and modifiability,all while retaining the distinctive traits associated with halide perovskites ranging from diverse structures to tunable optoelectronic properties.This review article delves into the intrinsic attributes of O-PVSKs and critically examines the viability of O-PVSKs in X-ray detection,through which key features that distinguish O-PVSKs from traditional organic semiconductors and perovskites are outlined.This is followed by a perspective given on their future avenues for exploration.

Mixed low-dimensional metal halide perovskite singlecrystal for low-detection-limit x-ray detection via orientedion migration

Low-dimensional metal halide perovskites exhibit exceptional photoelectronicproperties and intrinsic stability, positioning them as a promising class of semiconductormaterials for light-emitting devices and photodetectors. In thiswork, we present a millimeter-scale single crystal of mixed low-dimensional(one-dimensional–zero-dimensional [1D–0D]) organic lead iodide withwell-defined crystallinity. The fabricated single-crystal devices demonstratehigh-sensitivity photoresponse and x-ray detection performance. By spatiallyisolating organic molecules to form the mixed 1D–0D crystal structure, ionmigrations is effectively suppressed, resulting in a remarkable three orders ofmagnitude reduction in the dark current (56.4 pA @200 V) of the single-crystaldevices. Furthermore, by enhancing the background characteristics, weachieved an impressive low x-ray detection limit of 154.5 nGys^(-1) in the singlecrystaldevice. These findings highlight that the mixed 1D–0D organic leadiodide configuration efficiently controls ion migration within the crystal structure,offering a promising avenue for realizing high-performance perovskitebasedphotodetectors and x-ray detectors.

Lead-free organic-inorganic hybrid scintillators for X-ray detection

Scintillators,which can convert high-energy particles(X-rays)into detectable lowenergy ultraviolet-visible-near-infrared photons,are essential components of X-ray detectors and show extensive practical applications in nondestructive detection and medical imaging.Traditionally,inorganic scintillators represented by CsI:Tl have achieved definite progress.However,the harsh preparation conditions,high production cost,and poor mechanical properties impede their potential development in the high-end X-ray imaging field.Organic-inorganic hybrid metal complexes could be excellent alternatives,by virtue of their structural and spectral tunability,good solution processability,and excellent photophysical properties.This review mainly focuses on eco-friendly lead-free metal(Mn^(2+),Cu^(+),Sb^(3+),Sn^(2+),Ge^(2+),Ln^(3+),etc.)complex scintillators.The luminescence mechanisms are introduced and the scintillation performance,such as light yield,limit of detection,imaging resolution,etc.,is highlighted.Moreover,the current challenges and perspectives in this emerging field are described.It is hoped to provide some theoretical guidance for the continuous development of the new scintillator systems.

Structure design of lead-free chiral-polar perovskites for sensitive self-powered X-ray detection

Metal halide perovskites have made significant progress in X-ray detection owing to their exceptional optoelec-tronic properties.However,most of these materials suffer from toxic element lead and require for high operating voltages.Hence,it is imperative to explore environmentally friendly perovskite crystals without external bias for X-ray detection.Herein,we strategically introduce chiral cations to synthesize a pair of lead-free chiral-polar hybrid perovskites(S-MPz)_(6)Bi_(3)I_(21)·6H_(2)O and(R-MPz)_(6)Bi_(3)I_(21)·6H_(2)O(1S and 1R,S/R-MPz=S/R-2-methylpipera-zinium),which exhibit strong circular dichroism(CD)signals with an anisotropic g-factor reaching approximately 0.017.Significantly,the chiral-polar feature gives rise to distinctive spontaneous polarization,which leads to a photovoltage of 1.1 V under X-ray illumination,endowing self-powered detection capabilities for X-ray.Further exploration of X-ray devices based on 1R single crystal(SC)demonstrates a high sensitivity of 5.2 pC Gy_(air)^(-1)cm^(-2)at zero bias.This study realizes passive X-ray detection depending on the intrinsic spontaneous polarization induced built-in electric field of chiral-polar perovskite,providing an effective approach to the chemical design of desired materials for high-performance"green"self-powered radiation detection.

Calibration of the Solar X-ray Detector on-board the Macao Science Satellite-1B for Soft X-ray Detection

The Solar X-ray Detector(SXD)on-board the Macao Science Satellite-1B(MSS-1B)was successfully launched via the Chinese Long March-2C rocket on 21 May 2023,and commenced operations in early June of the same year.The MSS-1B/Soft X-ray Detection Units(SXDUs)employ two silicon drift detectors(SDDs),providing a wide range of energy spectra spanning from 0.7 to 24 keV.Notably,the SXDUs deliver a high-resolution capability of 0.14 keV@5.9 keV and operate with a time cadence of 1 second.Here,we perform thorough calibrations of the MSS-1B/SXDUs,employing a combination of ground experiments and simulations.In addition,quantitative analysis comparing the flux measurements obtained by the MSS-1B/SXDUs to the data collected by the Geostationary Operational Environmental Satellite(GOES),provides compelling evidence of their consistency.Furthermore,the preliminary spectral analysis results showcase the robustness and expected performance of the MSS-1B/SXDUs,unlocking their potential for facilitating the study of dynamic evolution of solar flares.Moreover,the innovative MSS-1B/Solar X-ray Detector facilitates concurrent observations of solar soft and hard X-rays,thereby making valuable contributions to the advancements in solar research.

Advances in halide perovskite semiconductors for energy-integrated and energy-resolved X-ray detection

X-ray andγ-ray detectors are widely used in medical,military,security,material analysis,and industrial inspection.In recent years,perovskite materials have become promising materials for radiation detection owing to their strong stopping power,considerable carrier transportation ability,and simple synthesis process.Previous studies have demonstrated both direct and indirect radiation detectors using perovskite materials.In this review,we aim to elucidate the mechanism by which X-rays andγ-rays interact with matter,explain the principles of the energy integrating mode and photon counting mode for direct detection,and discuss the key factors determining device performance.Furthermore,we summarize recent advances in perovskite-based radiation detectors for both modes.Additionally,we identify challenges that need to be overcome to enable perovskite materials to be successfully commercialized.

An Enhanced Lung Cancer Detection Approach Using Dual-Model Deep Learning Technique

Lung cancer continues to be a leading cause of cancer-related deaths worldwide,emphasizing the critical need for improved diagnostic techniques.Early detection of lung tumors significantly increases the chances of successful treatment and survival.However,current diagnostic methods often fail to detect tumors at an early stage or to accurately pinpoint their location within the lung tissue.Single-model deep learning technologies for lung cancer detection,while beneficial,cannot capture the full range of features present in medical imaging data,leading to incomplete or inaccurate detection.Furthermore,it may not be robust enough to handle the wide variability in medical images due to different imaging conditions,patient anatomy,and tumor characteristics.To overcome these disadvantages,dual-model or multi-model approaches can be employed.This research focuses on enhancing the detection of lung cancer by utilizing a combination of two learning models:a Convolutional Neural Network(CNN)for categorization and the You Only Look Once(YOLOv8)architecture for real-time identification and pinpointing of tumors.CNNs automatically learn to extract hierarchical features from raw image data,capturing patterns such as edges,textures,and complex structures that are crucial for identifying lung cancer.YOLOv8 incorporates multiscale feature extraction,enabling the detection of tumors of varying sizes and scales within a single image.This is particularly beneficial for identifying small or irregularly shaped tumors that may be challenging to detect.Furthermore,through the utilization of cutting-edge data augmentation methods,such as Deep Convolutional Generative Adversarial Networks(DCGAN),the suggested approach can handle the issue of limited data and boost the models’ability to learn from diverse and comprehensive datasets.The combined method not only improved accuracy and localization but also ensured efficient real-time processing,which is crucial for practical clinical applications.The CNN achieved an accuracy of 97.67%in classifying lung tissues into healthy and cancerous categories.The YOLOv8 model achieved an Intersection over Union(IoU)score of 0.85 for tumor localization,reflecting high precision in detecting and marking tumor boundaries within the images.Finally,the incorporation of synthetic images generated by DCGAN led to a 10%improvement in both the CNN classification accuracy and YOLOv8 detection performance.

MARIE:One-Stage Object Detection Mechanism for Real-Time Identifying of Firearms

Security and safety remain paramount concerns for both governments and individuals worldwide.In today’s context,the frequency of crimes and terrorist attacks is alarmingly increasing,becoming increasingly intolerable to society.Consequently,there is a pressing need for swift identification of potential threats to preemptively alert law enforcement and security forces,thereby preventing potential attacks or violent incidents.Recent advancements in big data analytics and deep learning have significantly enhanced the capabilities of computer vision in object detection,particularly in identifying firearms.This paper introduces a novel automatic firearm detection surveillance system,utilizing a one-stage detection approach named MARIE(Mechanism for Realtime Identification of Firearms).MARIE incorporates the Single Shot Multibox Detector(SSD)model,which has been specifically optimized to balance the speed-accuracy trade-off critical in firearm detection applications.The SSD model was further refined by integrating MobileNetV2 and InceptionV2 architectures for superior feature extraction capabilities.The experimental results demonstrate that this modified SSD configuration provides highly satisfactory performance,surpassing existing methods trained on the same dataset in terms of the critical speedaccuracy trade-off.Through these innovations,MARIE sets a new standard in surveillance technology,offering a robust solution to enhance public safety effectively.

Advancements in Liver Tumor Detection:A Comprehensive Review of Various Deep Learning Models

Liver cancer remains a leading cause of mortality worldwide,and precise diagnostic tools are essential for effective treatment planning.Liver Tumors(LTs)vary significantly in size,shape,and location,and can present with tissues of similar intensities,making automatically segmenting and classifying LTs from abdominal tomography images crucial and challenging.This review examines recent advancements in Liver Segmentation(LS)and Tumor Segmentation(TS)algorithms,highlighting their strengths and limitations regarding precision,automation,and resilience.Performance metrics are utilized to assess key detection algorithms and analytical methods,emphasizing their effectiveness and relevance in clinical contexts.The review also addresses ongoing challenges in liver tumor segmentation and identification,such as managing high variability in patient data and ensuring robustness across different imaging conditions.It suggests directions for future research,with insights into technological advancements that can enhance surgical planning and diagnostic accuracy by comparing popular methods.This paper contributes to a comprehensive understanding of current liver tumor detection techniques,provides a roadmap for future innovations,and improves diagnostic and therapeutic outcomes for liver cancer by integrating recent progress with remaining challenges.

A novel detection method for warhead fragment targets in optical images under dynamic strong interference environments

A measurement system for the scattering characteristics of warhead fragments based on high-speed imaging systems offers advantages such as simple deployment,flexible maneuverability,and high spatiotemporal resolution,enabling the acquisition of full-process data of the fragment scattering process.However,mismatches between camera frame rates and target velocities can lead to long motion blur tails of high-speed fragment targets,resulting in low signal-to-noise ratios and rendering conventional detection algorithms ineffective in dynamic strong interference testing environments.In this study,we propose a detection framework centered on dynamic strong interference disturbance signal separation and suppression.We introduce a mixture Gaussian model constrained under a joint spatialtemporal-transform domain Dirichlet process,combined with total variation regularization to achieve disturbance signal suppression.Experimental results demonstrate that the proposed disturbance suppression method can be integrated with certain conventional motion target detection tasks,enabling adaptation to real-world data to a certain extent.Moreover,we provide a specific implementation of this process,which achieves a detection rate close to 100%with an approximate 0%false alarm rate in multiple sets of real target field test data.This research effectively advances the development of the field of damage parameter testing.