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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Compact Solid State Neutron-Gamma Detectors for Backpack or Handheld Instruments
摘要： In this paper, we report on the characterization of detectors constructed at RMD using 1-inch, 1.5-inch, and 2-inch diameter right cylinders of CLYC and CLLBC crystals coupled to arrays of silicon photomultipliers (SiPM). Detectors constructed with small volume CLLBC crystals coupled to a 12 mm × 12mm total area SiPM array show an excellent energy resolution of ~3% at 662 keV and a large volume CLYC crystal when coupled to a 24 mm × 24 mm area array shows an energy resolution of ~6.6% at 662 keV. Both detectors show pulse shape discrimination capabilities.
关键词： Gamma-ray detection,crystal growth,elpasolites,energy resolution,neutron detection,scintillation detector,CLLBC,CLYC,thermal neutrons
更新于2025-09-23 15:22:29
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Lean Body Mass Assessment Based on UV Absorbance in Spent Dialysate and Dual-Energy X-Ray Absorptiometry
摘要： Purpose: The aim of the study was to explore the possibility of assessing lean body mass (LBM) based on UV absorbance measurements in spent dialysate. Methods: 9 patients on chronic three-times-a-week HD (4 female, 5 male, mean age 58.8 ± 8.6 years) were studied. Blood and spent dialysate samples were collected for 3 consecutive hemodialysis (HD) sessions from every patient. A double-beam spectrophotometer was used for the determination of UV absorbance in the collected spent dialysate samples. Dual-energy x-ray absorptiometry (DXA) scans were performed on an interdialytic day. LBM was calculated based on creatinine concentration in blood (LBMblood) and UV absorbance in spent dialysate (LBMa) and assessed by DXA (LBMDXA). Also, in vitro experiments were carried out to investigate the effect of tissue hydration on DXA measurements. Results: Although LBMa was slightly lower compared to LBMblood, the estimates based on UV absorbance in spent dialysate presented greater accuracy and precision compared to LBMDXA. The significant difference between LBMblood and LBMDXA was with high probability caused by the altered tissue hydration of HD patents. Conclusions: In summary, the results show that it is possible to asses LBM based on UV absorbance in spent dialysate.
关键词： Lean body mass,Hemodialysis monitoring,Creatinine,Dual-energy x-ray absorptiometry,UV-absorption
更新于2025-09-23 15:22:29
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An FPGA-Oriented Algorithm for Real-Time Filtering of Poisson Noise in Video Streams, with Application to X-Ray Fluoroscopy
摘要： In this paper we propose a new algorithm for real-time ?ltering of video sequences corrupted by Poisson noise. The algorithm provides effective denoising (in some cases overcoming the ?ltering performances of state-of-the-art techniques), is ideally suited for hardware implementation, and can be implemented on a small ?eld-programmable gate array using limited hardware resources. The paper describes the proposed algorithm, using X-ray ?uoroscopy as a case study. We use IIR ?lters for time ?ltering, which largely simpli?es hardware cost with respect to previous FIR ?lter-based implementations. A conditional reset is implemented in the IIR ?lter, to minimize motion blur, with the help of an adaptive thresholding approach. Spatial ?ltering performs a conditional mean to further reduce noise and to remove isolated noisy pixels. IIR ?lter hardware implementation is optimized by using a novel technique, based on Steiglitz–McBride iterative method, to calculate ?xed-point ?lter coef?cients with minimal number of nonzero elements. Implementation results using the smallest StratixIV FPGA show that the system uses only, at most, the 22% of the resources of the device, while performing real-time ?ltering of 1024 × 1024@49fps video stream. For comparison, a previous FIR ?lter-based implementation, on the same FPGA, in the same conditions and constraints (1024 × 1024@49fps), requires the 80% of the logic resources of the FPGA.
关键词： Poisson noise,X-ray video?uoroscopy processing,Field-programmable gate array (FPGA),IIR ?ltering,IIR ?lter design,Real-time video ?ltering
更新于2025-09-23 15:22:29
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The Application of a New Model-Based Iterative Reconstruction in Low-Dose Upper Abdominal CT
摘要： Rationale and Objectives: To compare upper abdominal computed tomography (CT) image quality of new model-based iterative reconstruction (MBIR) with low-contrast resolution preference (MBIRNR40), conventional MBIR (MBIRc), and adaptive statistical iterative reconstruction (ASIR) at low dose with ASIR at routine-dose. Materials and Methods: Study included phantom and 60 patients who had initial and follow-up CT scans. For patients, the delay phase was acquired at routine-dose (noise index = 10 HU) for the initial scan and low dose (noise index = 20 HU) for the follow-up. The low-dose CT was reconstructed with 40% and 60% ASIR, MBIRc, and MBIRNR40, while routine-dose CT was reconstructed with 40% ASIR. CT value and noise measurements of the subcutaneous fat, back muscle, liver, and spleen parenchyma were compared using one-way ANOVA. Two radiologists used semiquantitative 7-scale (-3 to +3) to rate image quality and artifacts. Results: The phantom study revealed superior low-contrast resolution with MBIRNR40. For patient scans, the CT dose index for the low-dose CT was 3.00 ± 1.32 mGy, 75% lower than the 11.90 ± 4.75 mGy for the routine-dose CT. Image noise for the low-dose MBIRNR40 images was significantly lower than the low-dose MBIRc and ASIR images, and routine-dose ASIR images (p < 0.05). Subjective ratings showed higher image quality for low-dose MBIRNR40, with lower noise, better low-contrast resolution for abdominal structures, and finer lesion contours than those of low-dose MBIRc and ASIR images, and routine-dose ASIR images (p < 0.05). Conclusion: MBIRNR40 with low-contrast resolution preference provides significantly lower noise and better image quality than MBIRc and ASIR in low-dose abdominal CT; significantly better objective and subjective image quality than the routine-dose ASIR with 75% dose reduction.
关键词： Model-based iterative reconstruction,Abdominal CT.,X-ray computed tomography,Adaptive statistical iterative reconstruction,Radiation dose
更新于2025-09-23 15:22:29
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EDXRF for elemental determination of nanoparticle-related agricultural samples
摘要： The number of studies dealing with nanoparticles (NPs) and plants has increased. They subsidize the advances of agriculture in the 21st century; however, so far, beneficial as well as detrimental results have been reported. In this context, analytical tools for monitoring macronutrients and micronutrients in plants exposed to NPs, with adequate performance and low cost, are required. This work assesses the use of energy-dispersive X-ray fluorescence (EDXRF) spectrometry for elemental content evaluation in NP-containing agricultural samples. For Phaseolus vulgaris (common bean) seedlings treated with ZnO NP, CuO NP, and Fe3O4 NP, the limits of detection (LODs) were 0.4 mg kg?1 for Zn and Cu and 0.6 mg kg?1 for Fe after dry-ashing digestion, thus being suitable for NP oxide monitoring in seed priming. For submicron suspension fertilizers, Mn, Cu, and Zn were quantified as thin films after sample dilution. The LODs for Mn, Cu, and Zn were 0.09, 0.1, and 0.08 mg L?1, respectively. Finally, for P. vulgaris plants exposed to 300-nm ZnO NP, we monitored P, S, K, Ca, and Zn directly in powdered leaves, whose LODs ranged from 1.3 to 27 mg kg?1. No critical spectral interference was observed, and notable repeatability and suitable trueness were found in the cases of studies. EDXRF revealed itself a simple, fast, and reliable alternative to evaluate the elemental content in suspensions or the uptake of NP by plants.
关键词： agriculture,X-ray fluorescence,elemental determination,EDXRF,nanoparticles
更新于2025-09-23 15:22:29
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Role of polysiloxanes in the synthesis of aligned porous silicon oxycarbide ceramics
摘要： The present work focuses on establishing the role of polysiloxane precursors in the synthesis of aligned porous polymer derived silicon oxycarbide ceramics. The precursors used for the synthesis are, polymethylhydrosiloxane, vinyl terminated polydimethylsiloxane and cyclic tetramethyl-tetravinlycyclotetrasiloxane. Hydrotalcite is used for attaining aligned macroporosity during the crosslinking stage itself. Subsequently, pyrolysis of the sample has been carried out to synthesize the ceramics. The evolution of pore structure in these PDCs during the crosslinking and pyrolysis is co-related to the thermal decomposition behaviour. The pore morphology, structure and the size were analyzed using SEM, X-ray computed tomography and BET. Our studies confirm the presence of bimodal porosity in these PDCs. These PDCs have a specific surface area ranging from 77 - 160 m2/g and a total pore volume ranging from 0.18 - 0.29 cm3/g. These results could be significant for achieving a controlled synthesis process of porous materials suitable for various applications like adsorption, filtering and electrochemical storage.
关键词： Mesoporous,X-Ray computed tomography,Pyrolysis,Polymer derived ceramics,Specific surface area
更新于2025-09-23 15:22:29
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Abiotic reductive deiodination of iodinated organic compounds and X-ray contrast media catalyzed by free corrinoids
摘要： Iodinated X-ray contrast media are known for their stability concerning deiodination in the aquatic environment under aerobic conditions. In this study, we demonstrate the abiotic reductive deiodination of the iodinated contrast media iopromide, iopamidol and diatrizoate in the presence of corrinoids. In addition, triiodinated benzoic acid derivatives with iodine atoms bound at different positions were investigated. Corrinoids like cyanocobalamin (vitamin B12) and dicyanocobinamide served as electron shuttles and as catalysts between the reducing agent (e.g., titanium (III) citrate) and the electron accepting iodinated compound. The concentration decrease of the iodinated compounds followed first-order kinetics with rate constant kobs depending on the iodinated compound. A linear correlation between the rate of iodide release and the corrinoid concentration was observed, with deiodination rates for dicyanocobinamide twice as high as for vitamin B12. Reducing agents with a less negative standard redox potential like dithiothreitol or cysteine caused slower deiodination as the cobalt center was only reduced to its CoII oxidation state. With a temperature increase from 11 to 23 °C, the concentrations of released iodide doubled. A complete deiodination was only observed for the iodinated contrast media but not for structurally similar iodinated benzoic acid derivatives.
关键词： Vitamin B12,X-ray contrast media,Abiotic,Deiodination,Bank filtration,Corrinoids
更新于2025-09-23 15:22:29
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Ag2O/TiO2 nanostructures for the photocatalytic mineralization of the highly recalcitrant pollutant iopromide in pure and tap water
摘要： TiO2 was modified by the deposition of Ag2O nanoparticles to increase the photocatalytic degradation of iopromide in water under UV–C (λ = 254 nm) and UV–A/visible light irradiation (380–800 nm) using pure and tap water. Several loadings of Ag2O were deposited on TiO2, namely 0.03, 0.15, 0.25, 0.65, 1.0, 1.15, 1.35 and 1.8 wt. %. XRD, TEM, BET, ICP-OES, XPS, DRS and cathodoluminescence spectroscopy were carried out to characterize the materials, while semiconducting properties of the composite were elucidated through electrochemical and photoelectrochemical characterization. Under UV–C light irradiation, the Ag2O/TiO2 heterostructures showed higher mineralization of iopromide (up to 86%, using the 1.15 wt. % Ag2O/TiO2 material) than unmodified materials (37% for TiO2 and 14% for Ag2O), indicating a synergistic effect by the combination of both compounds in the composite. Under UV–A/visible light irradiation, mineralization achieved with the 1.15 wt. % Ag2O/TiO2 material decreased up to 65%, which was again higher than that obtained for its single components. Stability of the photocatalyst was observed through three consecutive reaction cycles under UV–A/visible light irradiation. In tap water, environmentally relevant concentrations of iopromide were tested (Co = 50 μg L?1), resulting in a high degradation rate, while mineralization dramatically decreased because of the matrix effect. Some by-products were identified by mass spectroscopy and a possible degradation path was proposed. The outstanding photocatalytic activity of the Ag2O/TiO2 materials was explained by the electron trap effect exerted by Ag2O, along with the appearance of different silver species (Ag2O, Ag2O2 and Ag°) throughout the photocatalytic reaction, enhancing the mobility of the charge carriers and thus the generation of reactive species on the photocatalyst surface.
关键词： Semiconductors,X-ray contrast media,Tap water,Photocatalysis,Composite
更新于2025-09-23 15:22:29
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Structure and properties of layered perovskites Ba1-Ln Fe1-Co O3-δ (Ln = Pr, Sm, Gd)
摘要： A series of samples of overall composition Ba1-xLnxFe1-yCoyO3-δ (Ln = Pr, Sm, Gd) with x = 0.3-0.4; y = 0-0.5 were prepared by glycerin nitrate technique in air. The crystal structure of single-phase Ba1-xLnxFe1-yCoyO3-δ (Ln = Pr, Sm, Gd) determined by XRD was described as cubic (sp. gr. Pm3(cid:1)m). However, transmission electronic microscopy revealed that both Sm- and Gd-doped oxides possess tetragonal structure with 5-fold and 3-fold increased c parameter respectively. Oxygen content in the complex oxides has been determined in air over wide temperature range by means of thermogravimetry and iodometric titration. The change in oxygen content with temperature for the phases with five-layered ordering was significantly smaller than for the disordered phases.
关键词： oxygen nonstoichiometry,X-ray diffraction,oxide materials,transmission electron microscopy,crystal structure
更新于2025-09-23 15:22:29
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Fabrication of AlN templates on SiC substrates by sputtering-deposition and high-temperature annealing
摘要： High-quality AlN templates fabricated by sputtering-deposition and post-deposition high-temperature annealing have great potential for deep ultraviolet light-emitting device applications. In this work, we fabricated AlN films on 6H-SiC substrates by sputtering and face-to-face annealing and characterized the structural quality of the AlN films before and after annealing. As reported in previous studies, to accomplish high-quality AlN films on SiC substrates using conventional methods, such as molecular beam epitaxy or metalorganic vapor phase epitaxy (MOVPE), it is important to grow the AlN on the SiC coherently. However, in this work, although the annealed AlN films were fully relaxed from the SiC substrates, or even had tensile strain, the AlN films indicated high crystallinity. The X-ray rocking curve full width at half maximum (XRC-FWHM) values of the 200-nm-thick annealed AlN film were 17 and 246 arcsec for the AlN (0002) and (10–12) diffraction, respectively. Though the annealed AlN film indicated rough surfaces with bunched step structures, the surface morphology was remarkably improved by MOVPE growth and clear atomic step-and-terrace structures were formed. The XRC-FWHM values of the MOVPE-grown AlN were 90 and 239 arcsec for the AlN (0002) and (10–12) diffraction, respectively.
关键词： A1. Stresses,A1. Atomic force microscopy,B1. Nitrides,B2. Semiconducting III-V materials,A1. X-ray diffraction
更新于2025-09-23 15:22:29