Ultrahigh-Sensitivity X-Ray Detectors Based on 4H-SiC n-p-n Structure

Deep learning techniques for automatically detecting teeth in dental X-rays have gained popularity, providing valuable assistance to healthcare professionals. However, teeth detection in X-ray images is often hindered by alterations in tooth appearance caused by dental prostheses. To address this challenge, our paper proposes a novel method for teeth detection and numbering in dental panoramic X-rays, leveraging two separate CNN-based object detectors, namely YOLOv7, for detecting teeth and prostheses, alongside an optimization algorithm to refine the outcomes. The study utilizes a dataset of 3138 radiographs, of which 2553 images contain prostheses, to build a robust model. The tooth and prosthesis detection algorithms perform excellently, achieving mean average precisions of 0.982 and 0.983, respectively. Additionally, the trained tooth detection model is verified using an external dataset, and six-fold cross-validation is conducted to demonstrate the proposed method’s feasibility and robustness. Moreover, the investigation of performance improvement resulting from the inclusion of prosthesis information in the teeth detection process reveals a marginal increase in the average F1-score, rising from 0.985 to 0.987 compared to the sole teeth detection method. The proposed method is unique in its approach to numbering teeth as it incorporates prosthesis information and considers complete restorations such as dental implants and dentures of fixed bridges during the teeth enumeration process, which follows the universal tooth numbering system. These advancements hold promise for automating dental charting processes.

Precise Cobb Angle Measurement System Based on Spinal Images Merging Function

SummaryX-ray detection and imaging technology has been rapidly developed for various fields since 1895, offering great opportunities to scientific and industrial communities. Particularly, flexible X-ray detectors have drawn numerous attention in medical-related applications, solving the uniform issues of traditional rigid X-ray detectors. Out of all the potential materials, metal halide perovskites (MHPs) have been emerged as excellent candidates as flexible X-ray scintillators and detectors owing to the advantages including low temperature solution processable, strong X-ray absorption coefficient, large mobility lifetime product and tunable bandgap. In this review, the recent advances of MHP-based flexible X-ray detectors are comprehensively summarized, focusing on the scalable synthesis technologies of materials and diverse device architectures, and covering both direct and indirect X-ray detection. A brief outlook that highlights the current challenges impeding the commercialization of flexible MHP-based X-ray detectors is also included with possible solutions to those problem being provided.

Modern X-ray detector systems urgently require compact, efficient, and fast data compression schemes to handle the transmission of big data from pixel arrays, enabling frame rates in the MHz regime. In this work, a data compression ASIC that implements a streaming fixed-length lossy compression scheme is introduced and analyzed, proving the feasibility and benefits of on-chip compression. The compression scheme utilizes a vector matrix product logic, which performs a number of floating-point multiplications, additions, and accumulations. The logic is verified, synthesized, and shown to fit in the area resource available for the X-ray detector under study, which comprises 192 × 168 pixels each of 12-bit width, and having a total area of 20 mm× 20 mm, about 2 mm× 20 mm of which are available for the digital logic. Several system architectures, precisions, and compression ratios ranging from 100 to 250 were analyzed to pave the way for on-chip fixed-length compression (e.g., principal component analysis, singular value decomposition) and data reduction (e.g., azimuthal integration) for X-ray and electron detectors.

Relative X-ray transition probabilities to the K-shell

The purpose of this paper is to investigate the characteristics of a novel cadmium-telluride (CdTe) photon counting detector optimized for X-ray imaging applications. CdTe was studied as a potential detector material for hard X-ray and gamma-ray detection. In this study, we used a CdTe photon counting detector manufactured by AJAT Ltd. (PID 350, Finland) for the purposes of both X-ray and gamma-ray detection. However, it is noted that X-ray detection can be limited by the characteristics of gamma-ray detectors. For the investigation of the characteristics of a detector for X-ray imaging, the detector has been studied in terms of detector calibration, count rate, and pixel sensitivity variation by using a poly-energetic X-ray. The detector calibration was evaluated to determine the effects of offset, gain, and energy. An optimal calibration increases the accuracy of the output energy spectrum. The pixel sensitivity variation was evaluated using profiles of various rows and columns from white (with X-ray) and dark (without X-ray) images. The specific trend of each image was observed around the edges of the hybrids. These pixel variations of the CdTe sensor were corrected. The image quality was improved by using the optimal correction method based on an understanding of the pixel sensitivity variation. The maximum recorded count rate of the detector was measured in all pixels. The count rate was measured by setting the energy windows from just above the noise level to the maximum energy. The average count rate was fairly linear up to 1.6 × 106 cps/8 modules and saturated at about 2.2 × 106 cps/8 modules. In this paper, we present several characteristics of the detector and demonstrate the improved spectrum and image obtained after calibration and correction. These results show that the novel CdTe photon counting detector can be used in conventional X-ray imaging, but exhibits limitations when applied to spectral X-ray imaging.

The present manuscript reviews our R&D studies on theapplication of large area avalanche photodiodes (LAAPDs) to thedetection of X-rays and vacuum ultraviolet (VUV) light. Theoperational characteristics of LAAPDs manufactured by AdvancedPhotonix Inc. were investigated for X-ray detection at roomtemperature. The optimum energy resolution obtained in four LAAPDsinvestigated was found to be in the range 10-18% for 5.9 keVX-rays. The observed variations are associated with dark currentdifferences between the several prototypes. LAAPDs have demonstratedhigh counting rate capability (up to about 105/s) and applicabilityin diverse areas, mainly low-energy X-ray detection, whereLAAPDs selected for low dark current may achieve better performancethan proportional counters. LAAPDs were also investigated as VUVphotosensors, presenting advantages compared to photomultipliertubes. X-rays are often used as a reference in light measurements;this may be compromised by the non-linearity between gains measuredfor X-rays and VUV-light. The gain was found to be lower for X-raysthan for VUV light, especially at higher bias voltages. For 5.9 keVX-rays, gain variations of 10% and 6% were measured relative to VUVlight produced in argon ( ∼ 128 nm) and xenon ( ∼ 172 nm) forgains of about 200. The effect of temperature on the LAAPD performancewas investigated for X-ray and VUV-light detection. Gain variations ofmore than -4% per oC were measured for 5.9 keV X-rays for gainsabove 200, while for VUV light variations are larger than -5% peroC. The energy resolution was found to improve with decreasingtemperature, what is mainly attributed to dark current. The excessnoise factor, another contribution to the energy resolution, wasexperimentally determined and found to be independent of temperature,increasing linearly with gain, from 1.8 to 2.3 for a 50-300 gainrange. The LAAPD response under intense magnetic fields up to 5 Teslawas investigated. While for X-ray detection the APD responsepractically does not vary with the magnetic field, for 172 nm VUVlight a significant amplitude reduction of more than 20% wasobserved.

A commercial-off-the-shelf (COTS) Si p+-i-n+ photodiode (Hamamatsu S5973), designed for visible and infrared detection, was repurposed for use as a low-cost and readily available detector for photon counting X-ray and γ-ray spectroscopy. The detector was investigated for its spectroscopic performance, while being coupled to a custom-made charge sensitive preamplifier, under the illumination of photons with energies up to 59.54 keV. The detector-preamplifier system was subjected to temperatures from 80 °C to 20 °C. Energy resolutions (Full Width at Half Maximum, FWHM) of 0.66 keV ± 0.05 keV at 5.9 keV, 0.70 keV ± 0.04 keV at 22.16 keV, and 0.74 keV ± 0.06 keV at 59.54 keV, were achieved at 20 °C. The energy resolution deteriorated at 80 °C, reaching a value of 1.8 keV ± 0.1 keV FWHM at 59.54 keV. The results suggested that the performance, in terms of energy resolution, of the currently reported COTS Si detector was better than that achieved with certain purpose-grown wide bandgap detectors at 20 °C and 40 °C and better than that achieved with other repurposed Si detectors at 20 °C, opening new possibilities for applications for the Hamamatsu S5973 detectors and increasing the availability of low cost X-ray and γ-ray spectroscopy instrumentation.

Neutron and X-ray Detectors

Arm fracture detection in X-rays based on improved deep convolutional neural network

Summary of Part I: The detection of X-rays by photographic recording, ionization chambers, proportional counters, scintillation counters, and semiconductor detectors is discussed. The extraordinary improvement in resolution achieved by semiconductor detectors resulted in a new powerful analytical method: detection of characteristic X-rays. Sample excitation, by X-rays, by charged particles produced by accelerators and by radioactive sources, is discussed. Charged particle induced X-ray emission is described within B framework of simple theoretical models. Experimental data on yields of X-rays produced by proton and heavy ion bombardment of different targets are summarized. The cross sections for the production of X-rays in ion-atom collisions are large. This allows the detection of elements present in very small amounts within the target, as well as the measurement of the charge of particles using beam foil spectroscopy. Part II of this article will describe some applications of X-ray emission spectroscopy in industry, water and air pollution, and in the study of the importance of trace elements in biology and medicine. Sensitivity, background problems, target preparation and data reduction for X-ray emission spectroscopy will be discussed.

Polycrystalline lead halide perovskite finds promising use in fabricating X-ray detectors with a large lateral size, adjustable thickness, and diverse synthesis processes. However, a large dark current hinders its development for weak signal detection. Herein, we propose a multistep pressing strategy for manufacturing a CsPbBr3/CsPbCl3 heterojunction wafer for a reduced dark current X-ray detector, and the device keeps a high sensitivity value after the insertion of a barrier by heterojunction; thus, the trade-off between sensitivity and dark current can be broken. The X-ray detector with a metal-semiconductor-metal structure yields a sensitivity of 6.32 × 104 μC Gyair-1 cm-2 at a bias of 12 V, a 1/f noise of 1.02 × 10-13 A/Hz-1/2, and a detection limit of 66.58 nGy s-1. These performance parameters are considerably better than those of a similar X-ray detector based on the single-structure wafer. The improved device performance of the heterostructure X-ray detector is ascribed to the suppressed carrier recombination, enhanced carrier transportation of the heterojunction, and strong X-ray attenuation of the CsPbCl3 layer. The pixel array device is further used in imaging applications. Hence, this study provides an efficient strategy for fabricating heterostructure polycrystalline lead halide perovskite wafers for use in high-performance wafer-based X-ray detectors.

X-ray detection has widespread applications in medical diagnosis, non-destructive industrial radiography and safety inspection, and especially, medical diagnosis realized by medical X-ray detectors is presenting an increasing demand. Perovskite materials are excellent candidates for high-energy radiation detection based on their promising material properties such as excellent carrier transport capability and high effective atomic number. In this review paper, we introduce X-ray detectors using all kinds of halide perovskite materials along with various crystal structures and discuss their device performance in detail. Single-crystal perovskite was first fabricated as an active material for X-ray detectors, having excellent performance under X-ray illumination due to its superior photoelectric properties of X-ray attenuation with μm thickness. The X-ray detector based on inorganic perovskite shows good environmental stability and high X-ray sensitivity. Owing to anisotropic carrier transport capability, two-dimensional layered perovskites with a preferred orientation parallel to the substrate can effectively suppress the dark current of the device despite poor light response to X-rays, resulting in lower sensitivity for the device. Double perovskite applied for X-ray detectors shows better attenuation of X-rays due to the introduction of high-atomic-numbered elements. Additionally, its stable crystal structure can effectively lower the dark current of X-ray detectors. Environmentally friendly lead-free perovskite exhibits potential application in X-ray detectors by virtue of its high attenuation of X-rays. In the last section, we specifically introduce the up-scaling process technology for fabricating large-area and thick perovskite films for X-ray detectors, which is critical for the commercialization and mass production of perovskite-based X-ray detectors.

A Californian firm, Digiray Corporation, has made a breakthrough in X-ray imaging technology by inventing the 'Reverse Geometry X-ray'® imaging system, that improved signal-to-noise ratio by two orders of magnitude. This was accomplished by inverting the X-ray tube anode with the X-ray detector. The patented reverse-geometry X-ray system (RGX®) has been improved since, by coupling multiple detectors and developed further into a motionless laminography system (MLX®). The scanning X-ray source is located near the object and the divergent X-ray beam passing through this object is detected by an array of 64 detectors at some distance from it. All detectors acquire data simultaneously at different angles. Data are digitised and then stored and processed in a computer. The key interest of this process is its high resolution and contrast sensitivity. This is largely due to reduced scatter, as a result of using reverse geometry between the X-ray and source and detector. This system has been used for detection of cracks and corrosion in aircraft wings and fuselages and many other NDT applications. NASA used it to detect flaws in the Space Shuttle fuel tank insulating foam and its heat-resistant tiles.

Progress and challenges of metal halide perovskites in X-ray detection and imaging