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Two-ply anode X-ray tube for computed tomography scanner
摘要： This report presents a method of the formation of tungsten layer on the graphite surface. The described method can be used to create the anode of powerful x-ray tubes for medical purposes, in particular, a computer tomograph (CT). The thermal properties of the graphite base and the deposited tungsten coating, as well as the strength of the resulting coating were studied. Thermal fields in the CT-anode with a power of 100 kW were calculated.
关键词： tungsten layer,thermal properties,tungsten coating,thermal fields,graphite surface,computer tomograph,x-ray tubes
更新于2025-09-04 15:30:14
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XPS investigation of F-doped MnO <sub/>2</sub> nanosystems fabricated by plasma assisted-CVD
摘要： Supported Mn(IV) oxide nanomaterials were prepared by plasma assisted-chemical vapor deposition from Ar/O2 plasmas starting from a fluorinated Mn(II) β-diketonate diamine adduct. Under the adopted conditions, the target compound served as a single-source molecular precursor for the obtainment of MnO2 nanosystems uniformly doped with fluorine. The overall F content in the target materials, composed of phase-pure β-MnO2, could be tailored as a function of the deposition temperature from 100 to 400 °C, a result of particular importance in view of photocatalytic and gas sensing applications. In the present study, attention is specifically devoted to the investigation of a representative specimen by means of x-ray photoelectron spectroscopy. Besides the wide scan spectrum, a detailed analysis of C 1s, O 1s, Mn 2p, Mn 3s, and F 1s photoelectron peaks is presented and discussed. The analyses reveal the formation of MnO2 free from other manganese oxides, with fluorine present in different chemical states, i.e., lattice F plus traces of precursor residuals at the system surface.
关键词： fluorine doping,x-ray photoelectron spectroscopy,PA-CVD,manganese oxide
更新于2025-09-04 15:30:14
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Femtosecond X-ray solution scattering reveals that bond formation mechanism of a gold trimer complex is independent of excitation wavelength
摘要： The [Au(CN)2]3 trimer in water experiences a strong van der Waals interaction between the d10 gold atoms due to large relativistic effect and can serve as an excellent model system to study the bond formation process in real time. The trimer in the ground state (S0) exists as a bent structure without the covalent bond between the gold atoms, and upon the laser excitation, one electron in the antibonding orbital goes to the bonding orbital, thereby inducing the formation of a covalent bond between gold atoms. This process has been studied by various time-resolved techniques, and most of the interpretation on the structure and dynamics converge except that the structure of the first intermediate (S1) has been debated due to different interpretations between femtosecond optical spectroscopy and femtosecond X-ray solution scattering. Recently, the excitation wavelength of 267 nm employed in our previous scattering experiment was suggested as the culprit for misinterpretation. Here, we revisited this issue by performing femtosecond X-ray solution scattering with 310 nm excitation and compared the results with our previous study employing 267 nm excitation. The data show that a linear S1 structure is formed within 500 fs regardless of excitation wavelength and the structural dynamics observed at both excitation wavelengths are identical to each other within experimental errors.
关键词： bond formation mechanism,Femtosecond X-ray solution scattering,gold trimer complex,excitation wavelength
更新于2025-09-04 15:30:14
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Atomic layer etching of chrome using ion beams
摘要： In this study, two Cr atomic layer etching (ALE) methods have been applied for the precise control of Cr etching. The first one involves O radical adsorption followed by Cl+ ion desorption (ALE with chemical ion desorption; chemical anisotropic ALE), and the second one involves Cl/O radical adsorption followed by Ar+ ion desorption (ALE with physical ion desorption; physical anisotropic ALE). Their effects on Cr etch characteristics were also investigated. For both the ALE methods, saturated Cr etch depth/cycle of 1.1 and 1.5 ? /cycle were obtained for the chemical and physical anisotropic ALE, respectively, while maintaining near-infinite etch selectivities with various Si-based materials like silicon, silicon dioxide, and silicon nitride. The ALE technique can be used to precisely control the thickness of materials, including metals such as Cr, without any surface damage.
关键词： etch selectivity,adsorption,atomic layer etching,x-ray photoelectron spectroscopy,ion beam,chrome
更新于2025-09-04 15:30:14
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Digital Tomosynthesis for Evaluating Metastatic Lung Nodules: Nodule Visibility, Learning Curves, and Reading Times
摘要： Objective: To evaluate nodule visibility, learning curves, and reading times for digital tomosynthesis (DT). Materials and Methods: We included 80 patients who underwent computed tomography (CT) and DT before pulmonary metastasectomy. One experienced chest radiologist annotated all visible nodules on thin-section CT scans using computer-aided detection software. Two radiologists used CT as the reference standard and retrospectively graded the visibility of nodules on DT. Nodule detection performance was evaluated in four sessions of 20 cases each by six readers. After each session, readers were unblinded to the DT images by revealing the true-positive markings and were instructed to self-analyze their own misreads. Receiver-operating-characteristic curves were determined. Results: Among 414 nodules on CT, 53.3% (221/414) were visible on DT. The main reason for not seeing a nodule on DT was small size (93.3%, ≤ 5 mm). DT revealed a substantial number of malignant nodules (84.1%, 143/170). The proportion of malignant nodules among visible nodules on DT was significantly higher (64.7%, 143/221) than that on CT (41.1%, 170/414) (p < 0.001). Area under the curve (AUC) values at the initial session were > 0.8, and the average detection rate for malignant nodules was 85% (210/246). The inter-session analysis of the AUC showed no significant differences among the readers, and the detection rate for malignant nodules did not differ across sessions. A slight improvement in reading times was observed. Conclusion: Most malignant nodules > 5 mm were visible on DT. As nodule detection performance was high from the initial session, DT may be readily applicable for radiology residents and board-certified radiologists.
关键词： Tomography,Learning curve,Pulmonary nodules,X-ray
更新于2025-09-04 15:30:14
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DukeSim: A realistic, rapid, and scanner-specific simulation framework in computed tomography
摘要： The purpose of this study was to develop a CT simulation platform that is 1) compatible with voxel-based computational phantoms, 2) capable of modeling the geometry and physics of commercial CT scanners, and 3) computationally efficient. Such a simulation platform is designed to enable the virtual evaluation and optimization of CT protocols and parameters for achieving a targeted image quality while reducing radiation dose. Given a voxelized computational phantom and a parameter file describing the desired scanner and protocol, the developed platform DukeSim calculates projection images using a combination of ray-tracing and Monte Carlo techniques. DukeSim includes detailed models for the detector quantum efficiency, quantum and electronic noise, detector crosstalk, subsampling of the detector and focal spot areas, focal spot wobbling, and the bowtie filter. DukeSim was accelerated using GPU computing. The platform was validated using physical and computational versions of a phantom (Mercury phantom). Clinical and simulated CT scans of the phantom were acquired at multiple dose levels using a commercial CT scanner (Somatom Definition Flash; Siemens Healthcare). The real and simulated images were compared in terms of image contrast, noise magnitude, noise texture, and spatial resolution. The relative error between the clinical and simulated images was less than 1.4%, 0.5%, 2.6%, and 3%, for image contrast, noise magnitude, noise texture, and spatial resolution, respectively, demonstrating the high realism of DukeSim. The runtime, dependent on the imaging task and the hardware, was approximately 2-3 minutes per rotation in our study using a computer with 4 GPUs. DukeSim, when combined with realistic human phantoms, provides the necessary toolset with which to perform large-scale and realistic virtual clinical trials in a patient and scanner-specific manner.
关键词： simulation,ray tracing,monte carlo,computational human phantoms,computed tomography,virtual clinical trial,in silico modeling,CT simulator
更新于2025-09-04 15:30:14
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I'm Not Sure What Bothers Me in this Chest X-Ray but an HRCT May Help?
摘要： There are some inevitable risk factors of patient exposure to problems arising from human errors, including missed subtle radiological findings, early identification of which may alter the patient outcomes. Here we are discussing a patient who presented with a prior diagnosis of seasonal allergic rhinitis with symptoms assumed to be bronchial asthma. A second review of chest radiograph after discussion over an online platform (Tabula Rasa group on Facebook) revealed some subtle findings which we missed initially. Further work-up of the case revealed some astonishing findings. This case illustrates the importance of discussing unsolved cases on online platforms with peers and also to proceed for higher imaging to detect what has been missed on plain radiography.
关键词： chest X ray,high resolution computed tomography,subtle findings
更新于2025-09-04 15:30:14
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Ferromagnetic Behavior and Electronic Characterization of ZnO Nanoparticles
摘要： In this work, Al-doped ZnO nanoparticles encapsulated with amorphous SiO2 were prepared by the wet chemical method. The obtained precursor was annealed and the nanoparticle sizes were controlled by adjusting the annealing temperature. These nanomaterials showed ferromagnetic behavior, even though the ZnO bulk crystal was diamagnetic. The results of electrical conductivity and XANES suggested that ferromagnetism of the Al-doped nanoparticles was results of carrier transport and oxygen vacancies. The Al-doped ZnO nanoparticles are extremely interesting from the perspective of solid state physics. [DOI: 10.1380/ejssnt.2018.406]
关键词： Nano-particles, quantum dots, and supra-molecules,Magnetic, structural, and other properties of nanostructures,Zinc oxide,Luminescence,Near edge extended X-ray absorption fine structure (NEXAFS)
更新于2025-09-04 15:30:14
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Radiation-responsive scintillating nanotheranostics for reduced hypoxic radioresistance under ROS/NO-mediated tumor microenvironment regulation
摘要： Abstract: Hypoxia-induced radioresistance is the primary reason for failure of tumor radiotherapy (RT). Changes within the irradiated tumor microenvironment (TME) including oxygen, reactive oxygen species (ROS) and nitric oxide (NO) are closely related to radioresistance. Therefore, there is an urgent need to develop new approaches for overcoming hypoxic radioresistance by incorporating TME regulation into current radiotherapeutic strategies. Methods: Herein, we explored a radiation-responsive nanotheranostic system to enhance RT effects on hypoxic tumors by multi-way therapeutic effects. This system was developed by loading S-nitrosothiol groups (SNO, a NO donor) and indocyanine green (ICG, a photosensitizer) onto mesoporous silica shells of Eu3+-doped NaGdF4 scintillating nanocrystals (NSC). Results: Under X-ray radiation, this system can increase the local dosage by high-Z elements, promote ROS generation by X-ray-induced photodynamic therapy, and produce high levels of NO to enhance tumor-killing effects and improve hypoxia via NO-induced vasodilation. In vitro and in vivo studies revealed that this combined strategy can greatly reinforce DNA damage and apoptosis of hypoxic tumor cells, while significantly suppressing tumor growth, improving tumor hypoxia and promoting p53 up-regulation and HIF1α down-regulation. In addition, this system showed pronounced tumor contrast performance in T1-weighted magnetic resonance imaging and computed tomography. Conclusion: This work demonstrates the great potential of scintillating nanotheranostics for multimodal imaging-guided X-ray radiation-triggered tumor combined therapy to overcome radioresistance.
关键词： X-ray induced photodynamic therapy,hypoxia-induced radioresistance,nanoscintillators,multimodal imaging,nitric oxide
更新于2025-09-04 15:30:14
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High-Quality Cuboid CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> Single Crystals for High Performance X-Ray and Photon Detectors
摘要： Organic–inorganic halide hybrid perovskite materials are promising materials for X-ray and photon detection due to their superior optoelectronic properties. Single-crystal (SGC) perovskites have increasingly attracted attention due to their substantially low crystal defects, which contribute to improving the figures of merit of the devices. Cuboid CH3NH3PbI3 SGC with the naturally favorable geometry for device fabrication is rarely reported in X-ray and photon detection application. The concept of seed dissolution-regrowth to improve crystal quality of cuboid CH3NH3PbI3 SGC is proposed and a fundamental understanding of the nucleation and growth is provided thermodynamically. The X-ray detector fabricated from cuboid CH3NH3PbI3 SGC demonstrates the firstly reported high sensitivity of 968.9 μC?1 Gy?1 cm?2 under ?1 V bias. The results also show that the favorable crystal orientation and high quality of cuboid CH3NH3PbI3 leads to better responsivity and faster response speed than the more common dodecahedral CH3NH3PbI3 in photodetection. Consequently, the work paves a way to synthesize high-quality perovskite SGCs and benefits the application of MAPbI3 SGCs with preferred crystal orientation and favorable crystal geometry for emerging device applications.
关键词： photodetector,cuboid,single crystal,perovskite,X-ray detector
更新于2025-09-04 15:30:14