Imaging Detector Research Articles

Innovative CQD detector for broadband multispectral imaging.

Innovative CQD detector for broadband multispectral imaging.

Advancing the Commercialization of Perovskite‐Based Radiation Detectors for High‐Resolution Imaging

AbstractRadiation detectors play an indispensable role in medical diagnostics, industrial non‐destructive inspection and national security. Recently, halide perovskites are considered as the new generation of radiation active materials due to excellent optoelectronic properties such as adjustable bandgap, high absorption coefficient, high carrier mobility and low cost. The radiation detectors based on perovskite show high sensitivity and low detection limit, contributing to excellent spatial resolution for imaging. However, the commercialization of perovskite radiation detectors for high quality imaging still faces many challenges, including ion migration in perovskite, fermi level pinning and electrochemical reaction at the interface of perovskite/electrode, and difficulties of integration with readout circuit. All the issues hinder the further improvement of device performance. This review summarizes the material forms and the optimized growth methods of perovskite for radiation imaging detectors. Further, this work focuses on challenges and improvements of the interface between perovskites and electrodes. Meanwhile, this work outlines the technical routes used to realize array detectors for radiation imaging. The comprehensive review would guide the commercialization of perovskite radiation detectors for high‐quality imaging.

High-sensitivity and spatial resolution benchtop cone beam XFCT imaging system with pixelated photon counting detectors using enhanced multipixel events correction method

Objective.High atomic number element nanoparticles have shown potential in tumor diagnosis and therapy. X-ray fluorescence computed tomography (XFCT) technology enables quantitative imaging of high atomic number elements by specifically detecting characteristic x-ray signals. The potential for further biomedical applications of XFCT depends on balancing sensitivity, spatial resolution, and imaging speed in existing XFCT imaging systems.Approach.In this study, we utilized a high-energy resolution pixelated photon-counting detector for XFCT imaging. We tackled degradation caused by multi-pixel events in the photon-counting detector through energy and interaction position corrections. Sensitivity and spatial resolution imaging experiments were conducted using PMMA phantoms to validate the effectiveness of the multi-pixel events correction algorithm.Main results.After correction, the system's sensitivity and spatial resolution have both improved. Furthermore, XFCT/CBCT dual-modality imaging of gadolinium nanoparticles within mice subcutaneous tumor was successfully achieved.Significance.These results demonstrate the preclinical research application potential of the XFCT/CBCT dual-modality imaging system in high atomic number nanoparticle-based tumor diagnosis and therapy.

Breakthrough 4π helium ion energy spatial distribution in plasma focus space applying novel mega-size panorama cylindrical ion image detector

Breakthrough 4π helium ion energy spatial distribution in plasma focus space applying novel mega-size panorama cylindrical ion image detector

Imaging simulation analysis of space targets by different observed orbits

Abstract For most optical simulations of space targets, static imaging characteristics are studied with a pre-set angle and attitude which are less consistent with the actual situation for satellite detectors’ dynamic image. Especially when the detector and the target are in different orbits, the imaging angles and attitudes also vary. In this article, two kinds of observed orbits are selected to simulate the detector image results, and the observed attitude and angle are updated over time through the simulation process. Furthermore, a temperature field of the space target is also calculated as preconditioned data to be taken into account in the optical simulation, instead of roughly estimating the temperature. The result of the study reveals that when the satellite detector and target operate at coplanar orbits, closer distances (ranging from 236 km to 28 km) allow for the acquisition of more specific details regarding the target’s characteristics. This research may offer a new approach to selecting orbits to obtain high-quality imaging data.

Development of crystal optics for X-ray multi-projection imaging for synchrotron and XFEL sources.

X-ray multi-projection imaging (XMPI) is an emerging experimental technique for the acquisition of rotation-free, time-resolved, volumetric information on stochastic processes. The technique is developed for high-brilliance light-source facilities, aiming to address known limitations of state-of-the-art imaging methods in the acquisition of 4D sample information, linked to their need for sample rotation. XMPI relies on a beam-splitting scheme, that illuminates a sample from multiple, angularly spaced viewpoints, and employs fast, indirect, X-ray imaging detectors for the collection of the data. This approach enables studies of previously inaccessible phenomena of industrial and societal relevance such as fractures in solids, propagation of shock waves, laser-based 3D printing, or even fast processes in the biological domain. In this work, we discuss in detail the beam-splitting scheme of XMPI. More specifically, we explore the relevant properties of X-ray splitter optics for their use in XMPI schemes, both at synchrotron insertion devices and XFEL facilities. Furthermore, we describe two distinct XMPI schemes, designed to faciliate large samples and complex sample environments. Finally, we present experimental proof of the feasibility of MHz-rate XMPI at the European XFEL. This detailed overview aims to state the challenges and the potential of XMPI and act as a stepping stone for future development of the technique.

Second generation stationary chest tomosynthesis with faster scan time and wider angular span.

Digital tomosynthesis has shown potential for increasing specificity and sensitivity compared to radiography for low-dose chest imaging. Prior investigation of the s-DCT system indicated potential, but additional iteration with improved scan speed, power, and angular span was necessary for translation. The study aims to demonstrate and characterize a second-generation stationary digital chest tomosynthesis (s-DCT) scanner with increased x-ray energy, tube current, and larger angular span. The second-generation s-DCT system employed a meter-long linear carbon nanotube (CNT) source array integrated with a digital detector and patient imaging table. Tube output, focal spot size, modulation transfer function (MTF), artifact spread function (ASF), and imaging performance were evaluated. A lung phantom with simulated nodules was imaged for clinical task-based demonstration. The scanner achieved a 6s scan time, significantly improved from the prior generation's 16s. The x-ray tube exhibited good current stability, with 20.4±0.6mA tube current and focal spot size aligned with specifications (IEC 0.8). The MTF confirmed enhanced spatial resolution of 2.4lp/mm, comparable to commercial chest tomosynthesis systems. The ASF indicated improved depth resolution (5.2mm, previously 9.5mm). Phantom imaging showcased visualization of both high and low-attenuation lung nodules. The second-generation s-DCT system exhibited improved performance in terms of tube power, scan time, and image quality. Enhanced in-plane and depth resolution, along with faster imaging, suggest potential clinical benefits for improved diagnoses. Further clinical validation is warranted to ascertain the system's clinical utility.

GoToCloud optimization of cloud computing environment for accelerating cryo-EM structure-based drug design

Cryogenic electron microscopy (Cryo-EM) is a widely used technique for visualizing the 3D structures of many drug design targets, including membrane proteins, at atomic resolution. However, the necessary throughput for structure-based drug design (SBDD) is not yet achieved. Currently, data analysis is a major bottleneck due to the rapid advancements in detector technology and image acquisition methods. Here we show “GoToCloud”, a cloud-computing-based platform for advanced data analysis and data management in Cryo-EM. With GoToCloud, it is possible to optimize computing resources and reduce costs by selecting the most appropriate parallel processing settings for each processing step. Our benchmark tests on GoToCloud demonstrate that parallel computing settings, including the choice of computational hardware, as well as a required target resolution have significant impacts on the processing time and cost performance. Through this optimization of a cloud computing environment, GoToCloud emerges as a promising platform for the acceleration of Cryo-EM SBDD.

Enhanced Timing Performance of Dual-Ended PET Detectors for Brain Imaging Using Dual-Finishing Crystal Approach.

This study presents a novel approach to enhancing the timing performance of dual-ended positron emission tomography (PET) detectors for brain imaging by employing a dual-finishing crystal method. The proposed method integrates both polished and unpolished surfaces within the scintillation crystal block to optimize time-of-flight (TOF) and depth-of-interaction (DOI) resolutions. A dual-finishing detector was constructed using an 8 × 8 LGSO array with a 2 mm pitch, and its performance was compared against fully polished and unpolished crystal blocks. The results indicate that the dual-finishing method significantly improves the timing resolution while maintaining good energy and DOI resolutions. Specifically, the timing resolution achieved with the dual-finishing block was superior, measuring 192.0 ± 12.8 ps, compared to 206.3 ± 9.4 ps and 234.8 ± 17.9 ps for polished and unpolished blocks, respectively. This improvement in timing is crucial for high-performance PET systems, particularly in brain imaging applications where high sensitivity and spatial resolution are paramount.

Multispectral pattern camouflage materials based on PU/Al-flake composite: A CNN-based evaluation

With the continuous progress in optical sensor technologies, the emergence of imagery detection systems operating in the infrared (IR) band has become a reality. In response, we present a novel approach designed to deceive imagery IR detectors targeting fighter jets. To implement this method, we developed a specialized coating technique using a Polyurethane (PU)/Aluminum (Al)-flake composite. This composite coating enables the precise application of IR camouflage patterns while preserving the existing visible camouflages on aircraft surfaces. We customized fighter jet IR image datasets by integrating flow and heat transfer numerical analysis results with real-world background measurements. We then employed the YOLOv3 algorithm, based on a convolutional neural network (CNN), which is known for its high performance in object detection. Through this approach, we analyzed the effects of various pattern shapes on camouflage performance. The proposed PU/Al-flake composite coating offers a versatile and effective solution for overlapping IR camouflage patterns onto existing visible camouflages, providing enhanced protection against advanced IR imagery detection systems. This study highlights the potential of a comprehensive approach to developing and evaluating multispectral camouflage materials and effective camouflage strategies, emphasizing practical applications and real-world performance against IR image detectors.

Carryover slag weight prediction under converter tapping process by applying attention-shifting infrared thermal mapping technique

The prediction model of actual slag weight under converter tapping process was constructed by applying attention-shifting infrared thermal mapping technique. Firstly, the linkage between programmable logic controller signal of the converter mechanical structure and the infrared thermal mapping detector image was realized to ensure the real-time monitoring of the whole tapping process. Images should be preprocessed to ensure a good distinction between the flowing liquid and background at the tapping beginning, furthermore to separated slag from liquid steel at the following process. Moreover, the use of attention-shifting block belonging to the infrared thermal detector was effect to obtain more accurate image distinction between the liquid steel and slag. Hence the gray degree threshold value was adjusted to 220–225 in the early stage, and the value was needed to be lowered to 170–176 in the end. After using the model, the slag weight was less than < 8.0kg/t when only slag-stopping awl was adopted in tapping process. The average weight of slag in converter was 7.3kg/t by using slag-stopping awl and sliding plate slag-blocking.

Spatial resolution studies using point spread function extraction in optically read out Micromegas and GEM detectors

Optically read out gaseous detectors are used in track reconstruction and imaging applications requiring high granularity images. Among resolution-determining factors, the amplification stage plays a crucial role and optimizations of detector geometry are pursued to maximize spatial resolution. To compare Micro Pattern Gaseous Detector (MPGD) technologies, focused low-energy X-ray beams at the SOLEIL synchrotron facility were used to record and extract point spread function widths with MICRO-Mesh Gaseous Structure (icromegas) and Gas Electron Multiplier (GEM) detectors. Point spread function width of ≈108µm for Micromegas and ≈127µm for GEM foils were extracted. The scanning of the beam with different intensities, energies and across the detector active region can be used to quantify resolution-limiting factors and improve imaging detectors using MPGD amplification stages.

Reduction of speckle effect using galvanometer scanners in a laser-based uniform source for radiance responsivity measurement

Narrow linewidth lasers play an important role in high-spectral and high-precision radiometric calibration. In this paper, a standard uniform light source for radiometric calibration of imaging detectors and devices is designed and realized based on narrow linewidth laser and intergrating sphere. Because the speckle effect caused by laser has a great influence on the radiance transfer, galvanometer scanners were employed to reduce the speckle effect. CCD method was used to measure the nonuniformity of the middle row/column of the integrating sphere exit, and nonuniformity reduced from 2.6 % to 0.72 % when the galvanometer scanners were turned on. By superimposing 9 different regions of static speckle image, the non-uniformity is greatly reduced, which is consistent with the experimental results. The output radiance stability of the source is measured with an improvement from 8.4 × 10-5 to 2.7 × 10-5. Finally, the nonuniformity of the source is measured to be 0.15 % by a spot luminance meter.

Optimized substrate temperature for high-quality CdZnTe epitaxial film in X-ray flat panel detectors

Cadmium zinc telluride (CdZnTe or CZT) materials, favored for their physical superiority in optoelectronic applications, can be efficiently produced as large-area epitaxial film via close space sublimation (CSS), enhancing potential in flat-panel detector imaging. However, the application of CdZnTe epitaxial film in medical imaging equipment is limited by their lower resistivity, prolonged response times, and diminished sensitivity. By elevating the substrate temperature, we enhanced the number and depth of reverse sublimation pits on the surface of the CdZnTe epitaxial film, established an approximately 100 nm Zn-rich layer, broadened the bandwidth, and minimized electrode injection. Additionally, we observed an aggregation of dislocations at the edges of the reverse sublimation pits, which promoted surface recombination and reduced leakage current. These modifications significantly increased the film's resistivity to 1011 Ω cm. Further, they notably decreased the rise and drop times to 2 m s and 4 m s, respectively. Integrated with thin-film transistors (TFTs), the optimized CdZnTe epitaxial film now distinctly differentiate between air, plastics, and metals under X-ray examination. This improved performance of X-ray flat panel detectors (FPDs) based on CdZnTe epitaxial film is promising for the development of next-generation X-ray detection systems.

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.

Desenvolvimento de metodologia para medição do fator output para blocos de elétrons

In light of the routine verification of output factor for electron blocks manufactured for patients and outside the standard square field measurements, this study proposes a methodology for measuring the output factor using EPID, validated by water measurements with a diode, and employing Python programming to analyze the pre-processed detector images. The study used square and rectangular blocks to validate the code and evaluate the limitations of the EPID, finding an agreement of up to ±3.0% for fields larger than 6.0 cm² and ±5.0% for fields between 3.0 cm² and 5.0 cm². The final evaluation aimed to compare square field measurements with asymmetric rectangular fields, and the results showed deviations of less than ±1.0%, thus indicating the feasibility of using EPID for this methodology.

High repetition-rate laser-induced breakdown spectroscopy combined with two-dimensional correlation method for analysis of sea-salt aerosols

Laser-induced breakdown spectroscopy (LIBS) offers a tantalizing glimpse into real-time, on-the-spot aerosol analysis. Yet, the reliance on traditional lasers, with their limitations in energy and frequency, hampers optimal sample handling, dissociation, and excitation. To address those challenges, we propose a novel tactic: utilize a high repetition-rate (rep.-rate) laser with low pulse energy in combination with the two-dimensional correlation (2D-corr.) technique for sea-salt aerosols analyses. By examining the emission patterns from both the laser pulse train and individual pulses, we recognize distinctive analyte-specific rep.-rate responses, which allowed spectral reconstruction of analytes, avoiding background interferences. This discovery enabled the rep.-rate modulation for a 2D-corr. spectroscopy workflow. Consequently, we successfully differentiated between particle-related and air-species-related spectral components, obviating expensive spectrometers or intensified image detectors. For instance, the Na I at 589 nm stemming from aerosols exhibited an entirely different correlation contribution compared to O I at 777 nm, resulting in reconstructed clean aerosol-spectra without spectral peaks originated from air species. This 2D-corr. aerosol LIBS approach shows promising analytical potential streamlining aerosol particle analysis.

Calibration of a gamma ray Compton camera for radioactivity measurements

AbstractA dual-plane Compton imaging detector previously developed for prompt gamma imaging has been further tested and calibrated for quantitative radioactivity determination, specifically to assess radioactive debris from a reactor fuel element. The debris piece contains uranium isotopes and several long-lived fission products, including cesium-137 (Cs-137). The detector consists of two pixelated planes of cadmium-zinc-telluride (CZT) crystals which record gamma ray events interacting within these volumes. In addition to the energy spectrum obtained by pulse height analysis, the time-stamped events from each detector pixel are sorted by location into 3 categories for post-processing: intra-plane, inter-plane, and coincidence. An image reconstruction software enables spatial localization of the select gamma ray peak(s) from the spectrum, thereby separating the gamma ray by specific isotopes. We used the camera to image a small piece of debris for demonstration purposes. A measurement was performed alongside a high purity germanium (HPGe) detector, which could determine the isotopes' absolute activities and be used as a reference for the camera. In addition, a known isotopic point source was used to calibrate the camera’s energy detection efficiency in the same measurement geometry, correlating the image pixel intensity to the isotopic activity.

Vis-YOLO: a lightweight and efficient image detector for unmanned aerial vehicle small objects

Vis-YOLO: a lightweight and efficient image detector for unmanned aerial vehicle small objects

ANew Perspective On Arterioectatic Spinal Angiopathy with aReversible Pattern: Cause or Consequence?

In 2022, arterioectatic spinal angiopathy (AESA) of childhood was reported as afatal, progressive, multi-segment myelopathy associated with aunique form of non-inflammatory spinal angiopathy involving diffuse dilatation of the anterior spinal artery and cord congestion in children. In this study, we present four more cases of AESA, using early and long-term conventional imaging and flat detector computed tomography angiography (FDCTA) imaging to assess the probability of disease regression and prevent unnecessary interventions. We retrospectively reviewed the clinical and radiological findings of four patients with AESA seen in two neuroradiology departments between 2014 and 2023. The study included three boys and one girl. Two of the boys were siblings. Although the clinical and radiological presentation in the early stages of the clinical course overlapped the definition of AESA, the clinical course was more benign in three of the cases. The clinical courses of the two siblings with monosegmental cord involvement and largely reversible radiological findings suggest that some of the features in the initial definition of the disease cannot be standardized for all patients. The siblings had amutation of the NDUFS gene, which is involved in mitochondrial function and clinical-radiological reversibility in these patients. Many mitochondrial diseases, such as this NDUFS mutation, present with myelopathy, and mitochondrial diseases can sometimes show spontaneous recovery. It is crucial to identify other genetic mutations or environmental factors that trigger the accompanying vascular ectatic findings in AESA in larger multicenter studies to prevent its potential lethal course and possible unnecessary surgical-endovascular interventions.