X-ray Sensitivity Research Articles

Gradient Distributed and Tightly Integrated Perovskite Heterojunction Constructed by Electric Field-Driven Ion Deposition for High-Performance X-ray Detection.

Perovskite heterojunctions combine the advantages of two different components but suffer difficulties in the tightness of interconnection and limitation of material selection. Here we report an electric field-driven ion deposition (EFID) strategy that controllably deposits perovskite ions on heterogeneous single crystals to form a gradient heterojunction with tight integration. The interconnection force of the gradient heterojunction by the EFID method is much better than that of the solution-grown heterojunction, which is easily decomposed. An EFID-enabled heterojunction was constructed by depositing the 3D MAPbI3 perovskite on the 2D (FPEA)2PbI4 perovskite, exhibiting an excellent X-ray sensitivity of 2.12 × 104 μC Gy-1 cm-2 under an electric field of 500 V mm-1 and a low limit of detection (LoD) less than 12.01 nGy s-1, substantially better than that of the pristine 2D or 3D counterparts. This work expands the methodology for constructing perovskite heterojunctions, offering new perspectives for future perovskite heterojunction engineering.

Large Scale Lead-Free Perovskite Polycrystalline Wafer Achieved by Hot-Pressed Strategy for High-Performance X-Ray Detection.

Halide perovskites (HPs) have demonstrated excellent direct X-ray detection performance. Lead-free perovskite polycrystalline wafers have outstanding advantages in large-area X-ray imaging applications due to their area-scalability, thickness-controllability, large bulk resistivity, and ease of integration with large-area thin film transistor arrays. However, currently lead-free perovskite polycrystalline wafers possess low sensitivity, typically less than 1000 µC Gy-1 cm-2, which severely limits their X-ray detection applications. Here, high-quality and large scale polycrystalline wafers of AG3Bi2I9 (AG: aminoguanidinium) with short intercluster distances are successfully prepared using a hot-pressing method. The wafers possess high mobility-lifetime product of 5.66 × 10-3 cm2 V-1 and therefore achieve high X-ray sensitivity of 2675 µC Gy-1 cm-2, which can be comparable to those of the high-quality single crystal counterpart reported by the previous research (7.94 × 10-3 cm2 V-1 and 5791 µC Gy-1 cm-2), and represent the best results of the currently lead-free HP polycrystalline wafers. Besides, the wafers exhibit the X-ray detection limit as low as 11.8 nGy s-1, excellent long-term working stability, and high spatial resolution of 5.9 lp mm-1 in imaging. The findings demonstrate that AG3Bi2I9 polycrystalline wafers are feasible for high-performance X-ray detection and imaging system.

Large-Area Metal-Organic Framework Glasses for Efficient X-Ray Detection.

Cutting-edge techniques utilizing continuous films made from pure, novel semiconductive materials offer promising pathways to achieve high performance and cost-effectiveness for X-ray detection. Semiconductive metal-organic framework (MOF) glass films are known for their remarkably smooth surface morphology, straightforward synthesis, and capability for large-area fabrication, presenting a new direction for high-performance X-ray detectors. Here, a novel material centered on MOF glasses for highly uniform glass film fabrication customized for X-ray detection is introduced. MOF glasses, composed of zinc and imidazole derivatives, enable the transition from solid to liquid at low temperatures, facilitating the straightforward preparation of large-area and continuous MOF films with high mobility for X-ray device fabrication. Remarkably, MOF glass detectors demonstrate an exceptional sensitivity of 112.8 µC Gyair -1 cm-2 and a detection limit of 0.41 µGyair s-1, making them one of the most sensitive and with the best detection limits reported to date for MOF X-ray detectors. Clear X-ray images are successfully conducted using these developed MOF glass detectors for the first time. This breakthrough in X-ray sensitivity, and detection limit along with the spatial imaging resolution establishes a new standard for developing large-area and efficient MOF-based X-ray detectors with practical applications in medical and security screening.

Point-of-care lung ultrasound in the diagnosis of childhood pneumonia.

Lung ultrasound is emerging as a rapid, simple and safe alternative for diagnosing pneumonia since it has a higher sensitivity than X-rays and lower radiation exposure than computerized tomography. This is a prospective observational study done at a tertiary care centre in Chennai to study the diagnostic utility of lung ultrasound in pneumonia. Children aged 1 month to 12 years who were admitted to the hospital with complaints of cough, fever and/or breathing difficulty and on examination had tachypnea and/or chest indrawing were included in the study. All children underwent chest X-rays which was a standard hospital protocol. At admission, an independent investigator who was blinded to the clinical and radiological features of the child performed lung ultrasound. In all children, the final diagnosis of pneumonia was made by another independent expert paediatrician on the basis of the clinical features and chest X-ray. The test characteristics of ultrasound and chest X-ray were compared against this gold standard of physician-diagnosed pneumonia. Out of the 252 children studied, 225 (89.3%) had pneumonia while the rest 27 (10.7%) had other diagnoses. Among the 225 children with pneumonia, 223 (99.1%) were detected by ultrasound while 157 (69.8%) were detected by chest X-ray. All the test characteristics such as sensitivity, specificity, positive and negative predictive values of ultrasound were higher than those of chest X-ray. The sensitivity and specificity of ultrasound to diagnose pneumonia were 99.11% and 81.48%, respectively, while the sensitivity and specificity of X-ray for the same were 69.77% and 74.07%, respectively. Overall diagnostic accuracy for chest ultrasonography was 97.22% (94.36% to 98.88%), whereas for chest radiography, it was found to be 70.24% (64.18% to 75.81%).While both modalities were able to diagnose pneumonia significantly, ultrasound had better strength of association (Cramer's V value = 0.849) than X-ray to the final diagnosis. Lung ultrasound can be employed as a point-of-care investigation to diagnose pneumonia in suspected cases and can even replace chest X-ray in such circumstances.

Integrated ensemble CNN and explainable AI for COVID-19 diagnosis from CT scan and X-ray images

In light of the ongoing battle against COVID-19, while the pandemic may eventually subside, sporadic cases may still emerge, underscoring the need for accurate detection from radiological images. However, the limited explainability of current deep learning models restricts clinician acceptance. To address this issue, our research integrates multiple CNN models with explainable AI techniques, ensuring model interpretability before ensemble construction. Our approach enhances both accuracy and interpretability by evaluating advanced CNN models on the largest publicly available X-ray dataset, COVIDx CXR-3, which includes 29,986 images, and the CT scan dataset for SARS-CoV-2 from Kaggle, which includes a total of 2,482 images. We also employed additional public datasets for cross-dataset evaluation, ensuring a thorough assessment of model performance across various imaging conditions. By leveraging methods including LIME, SHAP, Grad-CAM, and Grad-CAM++, we provide transparent insights into model decisions. Our ensemble model, which includes DenseNet169, ResNet50, and VGG16, demonstrates strong performance. For the X-ray image dataset, sensitivity, specificity, accuracy, F1-score, and AUC are recorded at 99.00%, 99.00%, 99.00%, 0.99, and 0.99, respectively. For the CT image dataset, these metrics are 96.18%, 96.18%, 96.18%, 0.9618, and 0.96, respectively. Our methodology bridges the gap between precision and interpretability in clinical settings by combining model diversity with explainability, promising enhanced disease diagnosis and greater clinician acceptance.

In Situ Crystal Growth and Fusing-Confined Engineering of Quasi-Monocrystalline Perovskite Thick Junctions for X-ray Detection and Imaging.

Metal halide perovskites exhibit great promise for utilization in X-ray detection owing to their excellent optoelectronic properties and high X-ray attenuation capabilities. However, fabricating large-area thick films for high-performance perovskite X-ray detection remains challenging. This study develops an in situ crystal growth and fusing-confined approach to prepare high-quality, large-scale perovskite quasi-monocrystalline thick junctions. The perovskite crystals are grown in situ using a highly concentrated perovskite colloidal solution in 2-methoxyethanol. Introducing methylammonium chloride enhances grain reorganization during in situ growth and fusing-confined processes, effectively reducing grain boundaries and surface defects. This allows for the preparation of quasi-monocrystalline thick junctions of large grains (>100 μm) with high crystallinity, uniform orientation, and vertical penetration across the film thickness. Additionally, the carrier mobility and lifetime of the thick junctions are significantly enhanced. The optimized MAPbI3 detectors demonstrate an X-ray sensitivity of 2.6 × 104 μC Gyair-1 cm-2 and an exceptionally low detection limit of 1 nGyair s-1. Furthermore, inspired by a honeycomb structure, these detectors realize X-ray imaging in 64 × 64 pixels through a pixelated separation design, effectively reducing the charge-sharing effect. This study offers valuable insights into the preparation of large-scale perovskite quasi-monocrystalline thick junctions for highly sensitive X-ray detection and imaging applications.

Incidence of Ipsilateral Femoral Neck and Shaft Fractures in Pediatric and Adolescent Patients

OBJECTIVES: To identify the incidence, patient characteristics, and effectiveness of radiographic screening methods for detecting ipsilateral femoral neck and shaft fractures in pediatric and adolescent trauma patients. METHODS: Design: Retrospective cohort study. Setting: This study was conducted at a tertiary pediatric trauma hospital. Patient Selection Criteria: Patients younger than 18 years treated for a femoral shaft fracture between 2004 and 2018 were reviewed. Pathologic (metabolic bone disease or bone lesion), periprosthetic, and penetrating traumatic femoral shaft fractures were excluded. Outcome Measurements and Comparisons: Patient demographics, mechanisms of injury, treatment methods, and associated injuries were analyzed. Pretreatment x-rays and computed tomography (CT) scans were reviewed for the identification of ipsilateral femoral neck and shaft fractures. RESULTS: Among the 840 pediatric patients included in this study, 4 patients (0.5%) sustained ipsilateral femoral neck and shaft fractures. All the femoral neck fractures were observed in adolescents (aged 13–17 years) and involved in high-energy traumas. In adolescents involved in high-energy trauma, the incidence increased to 1.7%. Pretreatment sensitivity of both x-rays and CT scans was only 50% for the detection of femoral neck fractures. CONCLUSIONS: This study reveals that ipsilateral femoral neck and shaft fractures in pediatric patients are rare, occurring in adolescents involved in high-energy trauma. The findings suggest the need for a selective, rather than routine, use of CT scans based on the patient's age and the mechanism of injury. The use of alternative imaging methods such as magnetic resonance imaging should be considered to balance diagnostic accuracy while minimizing radiation exposure. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Development and performance evaluation of a thin GAGG:Ce scintillator plate for high resolution synchrotron radiation X-ray imaging

Scintillator-based X-ray imaging detectors are pivotal in numerous scientific and practical domains, including medical imaging, food and device inspection, and security monitoring. Recent advancements have spurred interest in 4D X-ray imaging using synchrotron radiation, necessitating higher temporal resolutions. Consequently, this places stringent demands on X-ray detector technology, especially when X-ray energy exceeds 20 keV. The selection of a suitable scintillator material is crucial for achieving optimal timing resolution, yet it poses a significant challenge in dynamic X-ray imaging. This study delves into the optimization of scintillator properties and their impact on spatial resolution and light output, elucidating the performance of Ce-doped Gd3Ga3Al2O12 (GAGG:Ce) scintillators for X-ray imaging applications. We developed a micro X-ray imaging detector using a 100 μm-thick GAGG:Ce scintillator plate and conducted X-ray imaging tests at the Aichi SR facility. The results demonstrated that the resolution, quantified as the chart slit width at a contrast transfer function (CTF) value of 10%, reached 2 ∼ 3 μm with a 4× lens, 0.52 μm± 0.03 μm with a 20× lens, and 0.42 μm± 0.01 μm with a 40× lens. Although the results of this study did not achieve a spatial resolution nearing the effective pixel size of the 40× lens, the text also elucidates the underlying reasons for this limitation. Furthermore, we compared the X-ray sensitivity of our GAGG:Ce scintillator plate with that of a commercial LuAG:Ce scintillator, revealing an approximately 1.5-fold increase in light output. As a demonstration, transmission images of dried small fish were captured using the GAGG:Ce scintillator plate and the developed X-ray imaging system. These findings highlight the potential of the X-ray imaging detector devised in this study for future generations of X-ray imaging applications.

Enhancing the X-ray Sensitivity of Cs2AgBiBr6 Double Perovskite Single Crystals through Cation Engineering.

Owing to their outstanding optoelectronic properties, halide perovskite (HP) materials have been employed in a wide range of applications, including solar cells, light-emitting devices, and X-ray detectors. Among them, lead-free double HPs are characterized by enhanced stability and reduced toxicity compared with lead-based alternatives. Cs2AgBiBr6, in particular, has emerged as a promising candidate for direct X-ray detection. The detection sensitivity, on the other hand, cannot yet compete with that of lead-containing perovskites. Developing schemes to improve X-ray detection efficiency is critical for reducing radiation exposure in medical imaging applications. Here, we investigate the potential of controlled doping and cation substitution with either lanthanides or small organic cations to improve the X-ray detection performance of Cs2AgBiBr6. Our findings reveal that by growing the perovskite in a slightly Bi-poor and Eu-rich environment, the X-ray sensitivity significantly increases 7-fold (from 17 to 120 μC Gyair -1 cm-2) and simultaneously improves the phototo-dark current ratio (from 2.5 to 29). Additionally, Cs-site substitution with imidazolium remarkably enhances the sensitivity over 10-fold (180 μC Gyair -1 cm-2), and ammonium enhances the phototo-dark current ratio to 37. Terahertz photoconductivity measurements reveal a positive correlation between enhanced X-ray sensitivity and improved charge transport properties (e.g., increased scattering time and, thus, carrier mobility) by doping. This study outlines straightforward strategies for boosting X-ray detection and fundamental photoconductivity in lead-free double HP, with potential implications for broader optoelectronic applications.

PEAI Surface Treatment for Low Ion Migration and High-Performance FAPbBr3 Single-Crystal X-ray Detectors.

Organometal halide perovskite single crystals (SCs) are the most promising candidates for the next generation of radiation detection materials. However, surface defects severely affect their detection performance and limit further applications. Here, we identified the surface defect types of FAPbBr3 SCs and employed phenethylammonium iodide (PEAI) solution to treat the crystal surface and to investigate their effects on ion migration, photoelectric performance, and X-ray detection performance. Our experimental results demonstrated that the surface defects, such as the metallic Pb and Br vacancies, can be effectively passivated by both the PEAI and the two-dimensional (2D) PEA2PbI4 layers. The PEAI layer can elongate the carrier lifetime, lower the trap density, and suppress ion migration in FAPbBr3 SCs. The 2D PEA2PbI4 layer can form a dense and full surface coverage, suppress ion migration, and lower the dark current of the SCs. The X-ray sensitivity of the PEAI-passivated FAPbBr3 SC detectors is 227.93 μCGyair-1 cm-2, which is an order of magnitude higher than that of the pristine FAPbBr3 SC detectors. This work demonstrates that surface treatment plays a critical role in the crystal quality and the X-ray detection performance of SCs.

ROLE OF POSTOPERATIVE CT SCAN IN ASSESSING SYNDESMOTIC REDUCTION IN ANKLE INJURIES

Background: Accurate syndesmotic reduction is necessary for achieving joint congruity and better functional outcomes. Radiographs alone don’t suffice, and CT scans are required for the evaluation of postoperative syndesmotic reduction. Methods: All patients who underwent ankle syndesmotic reduction and fixation from December 2019 to July 2021 were taken into the study. Predefined measurements were taken in postoperative radiographs and axial CT images were taken postoperatively. Sensitivity and specificity of X-rays when compared to CT scan were evaluated. Results: Twenty eight patients were included in the study and 13 cases were found to have syndesmotic malreduction in radiographs as per TCS and TFO in AP view and TFO and MCS measurements in mortise view. Five out of 28 cases were found to have syndesmotic malreduction in CT axial cuts as per standard anterior and posterior measurements. Hence 17.85% cases were malreduced in our study as per the gold standard (CT scan). The incidence of syndesmotic malreduction after fixation was 17.85%. Radiographs had a sensitivity of 60% and specificity of 56.5% in detecting malreduction. Conclusion: CT scan is necessary to accurately diagnose syndesmotic malreduction after open reduction and internal fixation of ankle fractures with associated syndesmotic injuries.

Handheld Ultrasound Devices Used by Newly Certified Operators for Pneumonia in the Emergency Department-A Diagnostic Accuracy Study.

The diagnostic accuracy of handheld ultrasound (HHUS) devices operated by newly certified operators for pneumonia is unknown. This multicenter diagnostic accuracy study included patients prospectively suspected of pneumonia from February 2021 to February 2022 in four emergency departments. The index test was a 14-zone focused lung ultrasound (FLUS) examination, with consolidation with air bronchograms as diagnostic criteria for pneumonia. FLUS examinations were performed by newly certified operators using HHUS. The reference standard was computed tomography (CT) and expert diagnosis using all medical records. The sensitivity and specificity of FLUS and chest X-ray (CXR) were compared using McNemar's test. Of the 324 scanned patients, 212 (65%) had pneumonia, according to the expert diagnosis. FLUS had a sensitivity of 31% (95% CI 26-36) and a specificity of 82% (95% CI 78-86) compared with the experts' diagnosis. Compared with CT, FLUS had a sensitivity of 32% (95% CI 27-37) and specificity of 81% (95% CI 77-85). CXR had a sensitivity of 66% (95% CI 61-72) and a specificity of 76% (95% CI 71-81) compared with the experts' diagnosis. Compared with CT, CXR had a sensitivity of 69% (95% CI 63-74) and a specificity of 68% (95% CI 62-72). Compared with the experts' diagnosis and CT diagnosis, FLUS performed by newly certified operators using HHUS devices had a significantly lower sensitivity for pneumonia when compared to CXR (p < 0.001). FLUS had a significantly higher specificity than CXR using CT diagnosis as a reference standard (p = 0.02). HHUS exhibited low sensitivity for pneumonia when used by newly certified operators.

Diagnostic accuracy of chest X-ray and CT using artificial intelligence for osteoporosis: systematic review and meta-analysis.

Artificial intelligence (AI)-based systems using chest images are potentially reliable for diagnosing osteoporosis. We performed a systematic review and meta-analysis to assess the diagnostic accuracy of chest X-ray and computed tomography (CT) scans using AI for osteoporosis in accordance with the diagnostic test accuracy guidelines. We included any type of study investigating the diagnostic accuracy of index test for osteoporosis. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, and IEEE Xplore Digital Library on November 8, 2023. The main outcome measures were the sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) for osteoporosis and osteopenia. We described forest plots for sensitivity, specificity, and AUC. The summary points were estimated from the bivariate random-effects models. We summarized the overall quality of evidence using the Grades of Recommendation, Assessment, Development, and Evaluation approach. Nine studies with 11,369 participants were included in this review. The pooled sensitivity, specificity, and AUC of chest X-rays for the diagnosis of osteoporosis were 0.83 (95% confidence interval [CI] 0.75, 0.89), 0.76 (95% CI 0.71, 0.80), and 0.86 (95% CI 0.83, 0.89), respectively (certainty of the evidence, low). The pooled sensitivity and specificity of chest CT for the diagnosis of osteoporosis and osteopenia were 0.83 (95% CI 0.69, 0.92) and 0.70 (95% CI 0.61, 0.77), respectively (certainty of the evidence, low and very low). This review suggests that chest X-ray with AI has a high sensitivity for the diagnosis of osteoporosis, highlighting its potential for opportunistic screening. However, the risk of bias of patient selection in most studies were high. More research with adequate participants' selection criteria for screening tool will be needed in the future.

In-situ investigation of damage evolution and mechanism in composite propellants under monochromatic X-ray irradiation

Synchrotron radiation monochromatic X-ray computed tomography (CT) is a powerful tool for in-situ characterization of the internal microstructure evolution in composite materials. However, prolonged X-ray irradiation during long-term in-situ studies may affect the structure and properties of material. While the effects of white beam irradiation have been widely investigated, the specific damage mechanisms and material sensitivity to monochromatic X-ray irradiation, particularly in composite materials like propellants, are not well understood. In this study, we identify the threshold irradiation time that triggers radiation damage in PBT propellant and observe the accumulation and worsening of damage over time, primarilyinitiated by ether bond cleavage, leading to radiation-induced decomposition and increased internal porosity. This resulted in a significant reduction in the mechanical strength of PBT propellant, particularly under prolonged exposure to synchrotron radiation. In contrast, the inert binder system HTPB propellant exhibited better radiation stability. Our study highlights the importance of considering both radiation-induced damage and material X-ray sensitivity when designing in-situ synchrotron radiation CT experiments for composite materials, and suggests that the development of dynamic experimental methods to further reduce the risk of radiation damage for high-reliability in-situ assessment of material properties, as well as the need for careful consideration of radiation effects in the design and safety evaluation of solid propellant systems working in extreme circumstance.

Ordered Transfer from 3D-Oriented MOF Superstructures to Polymeric Films: Microfabrication, Enhanced Chemical Stability, and Anisotropic Fluorescent Patterns.

Films and patterns of 3D-oriented metal-organic frameworks (MOFs) afford well-ordered pore structures extending across centimeter-scale areas. These macroscopic domains of aligned pores are pivotal to enhance diffusion along specific pathways and orient functional guests. The anisotropic properties emerging from this alignment are beneficial for applications in ion conductivity and photonics. However, the structure of 3D-oriented MOF films and patterns can rapidly degrade under humid and acidic conditions. Thus, more durable 3D-ordered porous systems are desired for practical applications. Here, oriented porous polymer films and patterns are prepared by using heteroepitaxially oriented N3-functionalized MOF films as precursor materials. The film fabrication protocol utilizes an azide-alkyne cycloaddition on the Cu2(AzBPDC)2DABCO MOF. The micropatterning protocol exploits the X-ray sensitivity of azide groups in Cu2(AzBPDC)2DABCO, enabling selective degradation in the irradiated areas. The masked regions of the MOF film retain their N3-functionality, allowing for subsequent cross-linking through azide-alkyne coupling. Subsequent acidic treatment removes the Cu ions from the MOF, yielding porous polymer micro-patterns. The polymer has high chemical stability and shows an anisotropic fluorescent response. The use of 3D-oriented MOF systems as precursors for the fabrication of oriented porous polymers will facilitate the progress of optical components for photonic applications.

Dense Perovskite Thick Film Enabled by Saturated Solution Filling for Sensitive X-ray Detection and Imaging.

Thick polycrystalline perovskite films synthesized by using solution processes show great potential in X-ray detection applications. However, due to the evaporation of the solvent, many pinholes and defects appear in the thick films, which deteriorate their optoelectronic properties and diminish their X-ray detection performance. Therefore, the preparation of large area and dense perovskite thick films is desired. Herein, we propose an effective strategy of filling the pores with a saturated precursor solution. By adding the saturated perovskite solution to the polycrystalline perovskite thick film, the original perovskite film will not be destroyed because of the solution-solute equilibrium relationship. Instead, it promotes in situ crystal growth within the thick film during the annealing process. The loosely packed grains in the original thick perovskite film are connected, and the pores and defects are partially filled and fixed. Finally, a much denser perovskite thick film with improved optoelectronic properties has been obtained. The optimized thick film exhibits an X-ray sensitivity of 1616.01 μC Gyair-1 cm-2 under an electric field of 44.44 V mm-1 and a low detection limit of 28.64 nGyair s-1 under an electric field of 22.22 V mm-1. These values exceed the 323.86 μC Gyair-1 cm-2 and 40.52 nGyair s-1 of the pristine perovskite thick film measured under the same conditions. The optimized thick film also shows promising working stability and X-ray imaging capability.

Exploring the clinical reasoning of an advanced clinical practitioner through a respiratory case encountered in primary care

Advanced clinical practitioners work autonomously, utilising a high degree of complex decision making within situations of clinical uncertainty. This case report examines the clinical reasoning surrounding the decision to refer a patient for a chest X-ray to confirm the presence of lung cancer. Although advocated for within clinical guidelines, the sensitivity of X-ray in the detection of early lung cancer has been questioned, and the value of alternative imaging in the form of low-dose computed tomography proposed. Conditions within clinical practice, including time constraints and fatigue, may negatively impact clinical reasoning. A national move towards 15-minute appointments in primary care would aid this.

Highly sensitive electron-beam-induced X-ray detection from liquid using SiNx membrane ultra-thinned by gas cluster ion beams

We aimed to improve the detection sensitivity for liquid measurement by developing an ultrathin photoelectron transmission window (SiNx membrane) for liquid cells via X-ray photoelectron spectroscopy or X-ray photoelectron emission microscopy at an ultrahigh vacuum. The membrane using gas-cluster ion beams (GCIB) was thinned, and its burst pressure was compared with those of membranes thinned with atomic 400 eV Ar+ ions. The SiNx membranes thinned by GCIB had approximately 2.5 times higher burst pressure than Ar+ ions. In addition, the improved sensitivity of the characteristic X-ray from liquid water induced by low-energy electrons was investigated. With the use of the 4.5 nm-thick SiNx membrane etched by GCIB, the X-ray intensity became 1.6 times higher than those of the 11 nm-thick pristine membrane at the electron beam (EB) energy of 1.5 keV. This result showed a good agreement with Monte Carlo simulation results of the EB-induced X-ray emission from liquid water beneath the SiNx membrane.

2D organic-inorganic lead perovskite: Advancing X-ray detection capability

Two-dimensional (2D) perovskite single crystals have risen to be prominent in the domain of optoelectronic materials due to their exceptional characteristics including notably low ion migration and defect density. A distinguishing feature is the strategic inclusion of larger organic amine spacer, alternately inserted between inorganic lead halide octahedral layers. This spacer effectively mitigates ion migration, even under higher bias voltages, which is particularly advantageous for X-ray detection. However, the simultaneous realization of multiple functions within this realm remains a formidable challenge. In this work, we have synthesized a high-quality organic spacer-incorporated single layered 2D perovskite single crystal of [CYP]PbBr4 (CYP = 1-cyclohexylpiperazine). Our findings reveal the impressive potential of [CYP]PbBr4 in the domain of X-ray detection, as evidenced by the ultrahigh X-ray sensitivity, long-term stability, and astonishingly low detection limit of 1.72 nGyairs-1. Notably, [CYP]PbBr4 also emits bright broadband yellow light with quantum yield of 30.3%, and the fabricated white LED achieves a high Color Rendering Index of 94.1, which surpasses that of commercially available white LED based on YAG: Ce3+ (< 80).

Probing Energy-Funneling Kinetics in Nanocrystal Sublattices for Superior X-Ray Imaging.

Long-lasting radioluminescence scintillators have recently attracted substantial attention from both research and industrial communities, primarily due to their distinctive capabilities of converting and storing X-ray energy. However, determination of energy-conversion kinetics in these nanocrystals remains unexplored. Here we present a strategy to probe and unveil energy-funneling kinetics in NaLuF4:Mn2+/Gd3+ nanocrystal sublattices through Gd3+-driven microenvironment engineering and Mn2+-mediated radioluminescence profiling. Our photophysical studies reveal effective control of energy-funneling kinetics and demonstrate the tunability of electron trap depth ranging from 0.66 to 0.96 eV, with the corresponding trap density varying between 2.38×105 and 1.34×107 cm-3. This enables controlled release of captured electrons over durations spanning from seconds to 30 days. It allows tailorable emission wavelength within the range of 520-580 nm and fine-tuning of thermally-stimulated temperature between 313-403 K. We further utilize these scintillators to fabricate high-density, large-area scintillation screens that exhibit a 6-fold improvement in X-ray sensitivity, 22 lp/mm high-resolution X-ray imaging, and a 30-day-long optical memory. This enables high-contrast imaging of injured mice through fast thermally-stimulated radioluminescence readout. These findings offer new insights into the correlation of radioluminescence dynamics with energy-funneling kinetics, thereby contributing to the advancement of high-energy nanophotonic applications.