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Multi‐energy computed tomography (MECT) offers the opportunity for advanced visualization, detection, and quantification of select elements (e.g., iodine) or materials (e.g., fat) beyond the capability of standard single‐energy computed tomography (CT). However, the use of MECT requires careful consideration as substantially different hardware and software approaches have been used by manufacturers, including different sets of user‐selected or hidden parameters that affect the performance and radiation dose of MECT. Another important consideration when designing MECT protocols is appreciation of the specific tasks being performed; for instance, differentiating between two different materials or quantifying a specific element. For a given task, it is imperative to consider both the radiation dose and task‐specific image quality requirements. Development of a quality control (QC) program is essential to ensure the accuracy and reproducibility of these MECT applications. Although standard QC procedures have been well established for conventional single‐energy CT, the substantial differences between single‐energy CT and MECT in terms of system implementations, imaging protocols, and clinical tasks warrant QC tests specific to MECT. This task group was therefore charged with developing a systematic QC program designed to meet the needs of MECT applications. In this report, we review the various MECT approaches that are commercially available, including information about hardware implementation, MECT image types, image reconstruction, and postprocessing techniques that are unique to MECT. We address the requirements for MECT phantoms, review representative commercial MECT phantoms, and offer guidance regarding homemade MECT phantoms. We discuss the development of MECT protocols, which must be designed carefully with proper consideration of MECT technology, imaging task, and radiation dose. We then outline specific recommended QC tests in terms of general image quality, radiation dose, differentiation and quantification tasks, and diagnostic and therapeutic applications. [ABSTRACT FROM AUTHOR]

Evolutionary multitask optimization (EMTO) has developed fast recently, and many algorithms have emerged that solve several different problems simultaneously through knowledge transfer. Most algorithms use a single search operator in their processing. However, different tasks have distinct characteristics, and a single operator is often inadequate to adapt to different stages of the same task. In this paper, we propose a multiple search operator selection strategy by adaptive probability allocation, named adaptive multi-operator selection (AMOS) to address EMTO that features rapid convergence of populations. It can automatically select the best multiple search operators based on the characteristics of specific tasks and different stages of evolution. The primary contributions of the proposed algorithm are as follows: (1) It combines the basic concepts of multi-operator integration and adaptive search operator selection to select the best multiple search operators for each task at different evolutionary stages; (2) It facilitates the knowledge transfer through different solving operators between tasks; (3) It can be flexibly embedded into various frameworks of general EMTO algorithms with good results. In the experiments, we validate the performance of AMOS on CEC2017 benchmark suite, CMTOPs benchmark suite, and real-world EMTO problems, and experimental results demonstrate the effectiveness and generality of the proposed strategy. [ABSTRACT FROM AUTHOR]

Controlling blood loss is crucial for saving lives during trauma. Based on the current application of solid waste in hemostatic materials, this study reports the synthesis of a hydroxyapatite/tourmaline composite material (referred to as ST) and a hemostatic sponge (referred to as STS). These materials were synthesized through hydrothermal processes and lyophilization techniques using seashells, tourmaline, and chitosan as precursors. The phase analysis and microstructure characterization were performed using XRD, SEM, TEM, and HRTEM. Owing to the spontaneous polarization of tourmaline attracting free ions in the system, the shells were deposited on the surface of tourmaline particles in the form of hydroxyapatite (HA) through dissolution and recrystallization during the hydrothermal process. HA can release free Ca2+, an important component in the coagulation system, while tourmaline can enhance cell metabolism by reducing water molecular clusters, thereby altering the permeability of cell membranes. ST particles were incorporated into the chitosan sponge matrix to prevent particle shedding. Through orthogonal design experiments on the preparation process of ST, the optimal preparation conditions were determined as follows: a hydrothermal temperature of 180 °C, a hydrothermal time of 12 h, a pH value of 8, and a shell-to-tourmaline ratio of 8 : 1. The composite materials were evaluated for their adsorption capacity, clotting time, hemolysis rate, antibacterial rate, and cytotoxicity. The results demonstrated a higher liquid adsorption rate, significantly reduced clotting time, a hemolysis rate of <5.0%, an antibacterial capacity of 88.5%, and lower cytotoxicity. These findings suggest that STS has the potential to be a safe, effective, and cost-efficient hemostatic agent. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article on the removal of emerging organic pollutants in drinking water and watershed water using zeolite mineral composite photocatalysts. The correction involves fixing citation numbers for references throughout the manuscript. The corrected references cover topics such as photocatalysis, wastewater treatment, heavy metal removal, and pollutant degradation. The document is a compilation of research articles and reviews on zeolites and their applications in environmental remediation, catalysis, and adsorption. The articles discuss the synthesis, characterization, and photocatalytic activity of zeolite-based materials, as well as their use in removing heavy metals and organic pollutants from water. The research highlights the potential of zeolites as efficient and sustainable materials for environmental applications. Additionally, the document includes a collection of scientific articles focusing on the use of clinoptilolite zeolite as a photocatalyst for degrading organic pollutants in wastewater. The articles explore the photocatalytic activity of different catalysts supported on clinoptilolite nanoparticles and investigate the degradation of various organic compounds. The studies demonstrate the potential of these photocatalysts for removing organic pollutants from wastewater and advancing water treatment technologies. Furthermore, the document provides a list of scientific articles discussing the photocatalytic degradation of pollutants like antibiotics, herbicides, dyes, and other organic compounds. The articles examine different photocatalysts and their effectiveness under simulated solar or visible light. They also discuss the use of materials like zeolite, titanium dioxide, [Extracted from the article]

Background: Global shortages of iodinated contrast media (ICM) during COVID‐19 pandemic forced the imaging community to use ICM more strategically in CT exams. Purpose: The purpose of this work is to provide a quantitative framework for preserving iodine CNR while reducing ICM dosage by either lowering kV in single‐energy CT (SECT) or using lower energy virtual monochromatic images (VMI) from dual‐energy CT (DECT) in a phantom study. Materials and Methods: In SECT study, phantoms with effective diameters of 9.7, 15.9, 21.1, and 28.5 cm were scanned on SECT scanners of two different manufacturers at a range of tube voltages. Statistical based iterative reconstruction and deep learning reconstruction were used. In DECT study, phantoms with effective diameters of 20, 29.5, 34.6, and 39.7 cm were scanned on DECT scanners from three different manufacturers. VMIs were created from 40 to 140 keV. ICM reduction by lowering kV levels for SECT or switching from SECT to DECT was calculated based on the linear relationship between iodine CNR and its concentration under different scanning conditions. Results: On SECT scanner A, while matching CNR at 120 kV, ICM reductions of 21%, 58%, and 72% were achieved at 100, 80, and 70 kV, respectively. On SECT scanner B, 27% and 80% ICM reduction was obtained at 80 and 100 kV. On the Fast‐kV switch DECT, with CNR matched at 120 kV, ICM reductions were 35%, 30%, 23%, and 15% with VMIs at 40, 50, 60, and 68 keV, respectively. On the dual‐source DECT, ICM reductions were 52%, 48%, 42%, 33%, and 22% with VMIs at 40, 50, 60, 70, and 80 keV. On the dual‐layer DECT, ICM reductions were 74%, 62%, 45%, and 22% with VMIs at 40, 50, 60, and 70 keV. Conclusions: Our work provided a quantitative baseline for other institutions to further optimize their scanning protocols to reduce the use of ICM. [ABSTRACT FROM AUTHOR]

One of the most challenging problems for people around the world is the lack of clean water. In the past few decades, the massive discharge of emerging organic pollutants (EOPs) into natural water bodies has exacerbated this crisis. Considerable research efforts have been devoted to removing these EOPs due to their biotoxicity at low concentrations. Heterogeneous photocatalysis via coupling clay minerals with nanostructured semiconductors has proven to be an economical, efficient, and environmentally friendly technology for the elimination of EOPs in drinking water and watershed water. Natural zeolite minerals (especially clinoptilolites) are regarded as appropriate supports for semiconductor-based photocatalysts due to their characteristics of having a low cost, environmental friendliness, easy availability, co-catalysis, etc. This review summarizes the latest research on clinoptilolites used as supports to prepare binary and ternary metal oxide or sulfide semiconductor-based hybrid photocatalysts. Various preparation methods of the composite photocatalysts and their degradation efficiencies for the target contaminants are introduced. It is found that the good catalytic activity of the composite photocatalyst could be attributed to the synergistic effect of combining the clinoptilolite adsorbent with the semiconductor catalyst in the heterogeneous system, which could endow the composites with an excellent adsorption capacity and produce more e−/h+ pairs under suitable light irradiation. Finally, we highlight the serious threat of EOPs to the ecological environment and propose the current challenges and limitations, before putting the zeolite mineral composite photocatalysts into practice. The present work would provide a theoretical basis and scientific support for the application of zeolite-based photocatalysts for degrading EOPs. [ABSTRACT FROM AUTHOR]

To achieve high value-added resource utilization of solid waste and reduce the cost of rubber manufacturing, this study utilizes finely structured municipal sludge (MS) with small particle size and abundant organic matter as the main raw materials. Through organic surface modification, rubber reinforcing fillers with surface affinity and compatibility are prepared. The effect of the amount of coupling agent bis-(triethoxysilyl-propyl)-tetrasulfide (Si69) on the properties of modified sludge powder (Si69-MS) reinforced styrene butadiene rubber (SBR) and its reinforcing mechanism were also studied. The results showed that when the mass fraction of Si69 was 1.5% of the MS, the adhesion work between Si69-MS and SBR increased from 88.34 to 101.42 mJ m−2, and the interfacial tension decreased from 25.45 to 0.34 mJ m−2. The tensile strength of the composite SBR reached 14.86 MPa, and the elongation at break reached 1829.1%. These findings indicate that the increased interface affinity between Si69-MS and the surface of SBR improves its dispersion within the SBR matrix, promoting the formation of a highly elastic composite rubber. [ABSTRACT FROM AUTHOR]

Background: Computed tomography (CT) number accuracy is important for quality assurance in CT imaging. However, in dual‐energy CT imaging, there are no widely used action limits for CT number accuracy in spectral images, information that is urgently needed. Purpose: To establish action limits for spectral CT images using longitudinal spectral data and an American College of Radiology (ACR) phantom. Methods: An ACR accreditation phantom was scanned routinely as part of a quality control program in our institution. We selected and analyzed 57 continuous weekly scans. The CT numbers or the density values of conventional and spectral images, including virtual monoenergetic images (40, 50, 70, 120, and 200 keV), iodine maps, calcium suppressed, and virtual non‐contrast images, were measured in the four inserts (solid water, bone, polyethylene, and acrylic) of the phantom. Longitudinal data were analyzed for correlation using Pearson's correlation coefficient (r) and standard deviation (SD). The SD ratios between spectral images and conventional images were calculated and the action limits for spectral images were established based on the action limits from the ACR. Results: Strong to very strong correlations (r > 0.70 or r < −0.70) were found among most spectral image types except the 200 keV images using solid water, polyethylene, and acrylic inserts (r = [−0.45, 0.64]). The SD ratio was highest for the 40 keV images, ranging from 2.8 to 6.5. The action limits of the bone insert were baseline ± 5.3 mg/mL for the iodine map and ranged from baseline ± 23.0 HU to baseline ± 391.9 HU for the other image types. The action limits for solid water ranged from baseline ± 4.1 HU to baseline ± 25.3 HU. The results for the polyethylene and the acrylic insert were close to those for solid water. Baselines can be established using the average of the initial 5∼10 measurements. Conclusions: Using longitudinal data, we estimated the action limits for CT number accuracy in the spectral images. This paves the way for establishing a comprehensive quality control program for spectral CT imaging. [ABSTRACT FROM AUTHOR]

Graphene-like carbon material was rapidly synthesized from waste bamboo stem as raw material with assistance of microwave heating and KHCO3 acting as both catalyst and activating agent. The graphene-like carbon material was composed of graphene-like nano sheets with high degree of graphitization, which had porous structure with specific surface area of 1887 m2/g. The product was evaluated as electrode material for supercapacitor and showed excellent electrochemical performance. At a current density of 0.5 A/g, the specific capacitance reached 204.0 F/g in the three-electrode system. After 10,000 cycles at 10.0 A/g current density, the maximum specific capacitance of a single electrode was 139.0 F/g, with the specific capacitance retention of 93.83%. While at a current density of 0.5 A/g, the maximum specific capacitance was 75.9 F/g in the coin-type symmetric supercapacitor, and after 5000 cycles at 10.0 A/g current density, the capacitance retention was 94.02%, showing a high capacitance retention. The experimental results indicated that microwave-assisted catalytic graphitization was a simple and fast process and it could potentially serve as an excellent green and low-cost methodology for preparation of graphene-like carbon material having good quality. [ABSTRACT FROM AUTHOR]

LiNi0.5Mn1.5O4 materials with hierarchical microsphere structure are prepared by PVP-assisted coprecipitation-hydrothermal method followed by high-temperature calcination. Effects of PVP molecular weights on the structure, morphology, and electrochemical properties of LiNi0.5Mn1.5O4 are investigated. It is found that PVP addition improves the crystallinity and disordering degree of LiNi0.5Mn1.5O4. PVP molecular weights exert great influence on the particle morphology. With the increase of molecular weight, primary particle size gradually decreases and secondary particle distribution becomes more uniform. Compared with LNMO-PVPM and LNMO-PVPH, LNMO-PVPL particle possesses extra {110} surface besides {111} and {100} surfaces. Electrochemical results show that PVP addition enhances the electrochemical performance of LiNi0.5Mn1.5O4, due to higher crystallinity, higher cation disordering degree, smaller primary particle size, and more uniform secondary particle distribution. LNMO-PVPL material exhibits the optimal electrochemical performance, due to extra {110} exposed surface and higher disordering degree, as well as relatively large primary particle size and slightly severe agglomerate structure. [ABSTRACT FROM AUTHOR]

In this study, ball mill pretreated iron ore tailings were modified with tetraethoxysilane (TEOS) and hexadecyltrimethoxysilane (HDTMS) to obtain iron ore tailings/polysiloxane (IOT/POS) superhydrophobic powders, which were subsequently mixed with chloroprene rubber solution (CRS) to prepare durable superhydrophobic composite coatings. The effect of HDTMS amount and reaction time on the wettability of the superhydrophobic powder was investigated. The influence of the superhydrophobic powders concentration on the wettability of the composite coatings as well as the degree of damage of the superhydrophobicity of the composite coating was analyzed by using the sandpaper abrasion and tape peeling tests. Further, SEM and FTIR were used to analyze the formation mechanism of the IOT/POS superhydrophobic powders and coatings. The results showed for an HDTMS amount of 2.5 mmol and reaction time of 4 h, the contact angle of the IOT/POS powder was 157.3 ± 0.6°, whereas the slide angle was determined to be 5.9 ± 0.8°. For an IOT/POS powder content of 0.06 g/mL in CRS, the contact angle value of the superhydrophobic composite coating was 159.2 ± 0.5°, whereas the slide angle value was 5.5 ± 0.8°. The superhydrophobic composite coating still maintained the superhydrophobicity after the sandpaper abrasion and tape peeling tests, which indicated the iron ore tailings solid waste has the potential to prepare superhydrophobic coatings. [ABSTRACT FROM AUTHOR]

Silica-based aerogel composite was prepared adopting sol–gel technique combined with atmospheric drying method utilizing waste environmentally hazardous iron tailings. High-temperature alkali fusion was applied to extract the Si, Al and Fe in the tailings so as to maximize recovery of valuable elements. The SiO2-Al2O3 (SA) and SiO2-Al2O3-Fe2O3 (SAF) aerogel composites were subjected to assess its adsorption capacity for macromolecules, utilizing methylene blue (MB) as the adsorbate. The specific surface areas of the SA and SAF aerogel were estimated to be 922.03 m2/g and 683.84 m2/g. The equilibrium adsorption capacity for MB was estimated to be 318.47 mg/g and 334.44 mg/g, respectively. Although the specific surface area of SAF was lower than SA, it offered higher MB adsorption capacity which could be attributed to the presence of iron oxide. The results promised utilization of iron tailing generated aerogel composite as a potential adsorbent for separation of high molecular weight compounds. [ABSTRACT FROM AUTHOR]

Summary: Spent zinc‐manganese batteries contain valuable elements, especially Zn and Mn, and recycling these metal elements can realize the sustainable development of resources. In this paper, a novel process of preparing ZnMn2O4 as anode material for lithium‐ion batteries from the spent zinc‐manganese battery is present. Nano ZnMn2O4 is synthesized by the low‐temperature hydrothermal method, and the formation mechanism is discussed. The structure, morphology, and composition of the products are characterized by XRD and SEM. The result shows that ZnMn2O4 with a crystal size of about 50 nm is prepared under the conditions of T = 200°C, pH = 7, reaction time t = 3 days, and n(Zn: Mn) = 0.966:2, which have the advantages of good crystallinity and high purity. The nanocrystallization and spheroid‐like structure of ZnMn2O4 determine that the battery assembled with ZnMn2O4 has a high initial discharge capacity, and the initial discharge specific capacity reaches 902.5 mAh g−1 at 0.1 A g−1. This study shows that the nano ZnMn2O4 synthesized by the hydrothermal method is a promising anode material for lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Purpose: Chemical shift‐encoded magnetic resonance imaging enables accurate quantification of liver fat content though estimation of proton density fat‐fraction (PDFF). Computed tomography (CT) is capable of quantifying fat, based on decreased attenuation with increased fat concentration. Current quantitative fat phantoms do not accurately mimic the CT number of human liver. The purpose of this work was to develop and validate an optimized phantom that simultaneously mimics the MRI and CT signals of fatty liver. Methods: An agar‐based phantom containing 12 vials doped with iodinated contrast, and with a granular range of fat fractions was designed and constructed within a novel CT and MR compatible spherical housing design. A four‐site, three‐vendor validation study was performed. MRI (1.5T and 3T) and CT images were obtained using each vendor's PDFF and CT reconstruction, respectively. An ROI centered in each vial was placed to measure MRI‐PDFF (%) and CT number (HU). Mixed‐effects model, linear regression, and Bland‐Altman analysis were used for statistical analysis. Results: MRI‐PDFF agreed closely with nominal PDFF values across both field strengths and all MRI vendors. A linear relationship (slope = −0.54 ± 0.01%/HU, intercept = 37.15 ± 0.03%) with an R2 of 0.999 was observed between MRI‐PDFF and CT number, replicating established in vivo signal behavior. Excellent test‐retest repeatability across vendors (MRI: mean = −0.04%, 95% limits of agreement = [−0.24%, 0.16%]; CT: mean = 0.16 HU, 95% limits of agreement = [−0.15HU, 0.47HU]) and good reproducibility using GE scanners (MRI: mean = −0.21%, 95% limits of agreement = [−1.47%, 1.06%]; CT: mean = −0.18HU, 95% limits of agreement = [−1.96HU, 1.6HU]) were demonstrated. Conclusions: The proposed fat phantom successfully mimicked quantitative liver signal for both MRI and CT. The proposed fat phantom in this study may facilitate broader application and harmonization of liver fat quantification techniques using MRI and CT across institutions, vendors and imaging platforms. [ABSTRACT FROM AUTHOR]

The superconducting fault current limiter (SFCL), as a very important power facility for high voltage DC system, can consume fault current energy and make DC breakers cut off fault transmission lines successfully. For the moment of reclosing DC breakers, the quench recovery time of the SFCL must be determined in advance. In this article, according to the design requirement of a 160 kV/1 kA resistance type DC SFCL in the Nan'ao multi-terminal flexible HVDC transmission demonstration project, the quench recovery time of a SCFL coil wound by two optical fiber encapsulated high temperature superconducting (OFE-HTS) tapes was checked by our optimized Raman-based distributed temperature sensing (Rm-DTS) system. The experimental results show that the used OFE-HTS tapes can withstand a 1500 A/100 ms AC short circuit current impact and are qualified with the SFCL. Furthermore, the quench recovery time of the SFCL coil measured by the Rm-DTS was 2930 ms. During the quench, the highest temperature zone occurred near the center of the SFCL coil. [ABSTRACT FROM AUTHOR]

CONNECTING FLUOROSCOPES TO THE TRIAD® SITE SERVER DICOM RDSR from fluoroscopes at participating facilities must be transferred to the TRIAD® Site Server, where they are anonymized before they are forwarded to the ACR DIR Central Server. The American College of Radiology (ACR) computed tomography (CT) Dose Index Registry (DIR) has been extraordinarily successful, with dose indices collected for over 102 million CT examinations to date.1,2 The CT DIR has provided an ongoing source of normative clinical data which has been the gold standard for national and international benchmarking.3 The largest existing normative dataset for fluoroscopically guided procedures is the Radiation Doses in Interventional Radiology (RAD-IR) study, with a data collection period covering the mid- to late 1990's.4-6 The RAD-IR study included 2142 clinical interventional fluoroscopy procedures, performed at one of seven sites using a single fluoroscope make and model. ACR National Radiology Data Registry (NRDR SP TM sp ), I The data warehouse for all ACR Registries, including, but not limited to, the Dose Index Registry (DIR), Lung Cancer Screening Registry (LCSR), and the General Radiology Improvement Database (GRID). CLINICAL PROCEDURE NAME MAPPING Facilities that participate in the Fluoroscopy DIR have their own internal facility clinical procedure "names" (a.k.a. procedure description, study description, etc.) for fluoroscopic procedures they perform. [Extracted from the article]

When short-circuit fault occurs in a voltage source converter–based high-voltage direct current (VSC-HVDC) transmission system, the fault current curve is much more complex than conventional AC power grid. The high-voltage DC circuit breaker with large cut-off capacity is rather expensive; thus, some current limiting methods are proposed to limit the fault current. The superconducting fault current limiter (SFCL) is one of the promising devices for both AC and DC short-circuit current limiting application. The optimization criterion for SFCL applied in VSC-HVDC system is presented, and a four terminal VSC-HVDC system is adopted as an example. The short-circuit fault could be divided into condenser discharge and AC system feeding process, and the fault current curve is related to the time-varying RLC parameters of the grid. The thermal and resistance characteristics of the SFCL are analyzed, and the optimization method of the current limiting impedance and thermal characteristics of the SFCL is developed based on the time-varying fault current. Finally, the design of a 160-kV SFCL was completed based on the proposed method. [ABSTRACT FROM AUTHOR]

Purpose: To describe a large, publicly available dataset comprising computed tomography (CT) projection data from patient exams, both at routine clinical doses and simulated lower doses. Acquisition and Validation Methods: The library was developed under local ethics committee approval. Projection and image data from 299 clinically performed patient CT exams were archived for three types of clinical exams: noncontrast head CT scans acquired for acute cognitive or motor deficit, low‐dose noncontrast chest scans acquired to screen high‐risk patients for pulmonary nodules, and contrast‐enhanced CT scans of the abdomen acquired to look for metastatic liver lesions. Scans were performed on CT systems from two different CT manufacturers using routine clinical protocols. Projection data were validated by reconstructing the data using several different reconstruction algorithms and through use of the data in the 2016 Low Dose CT Grand Challenge. Reduced dose projection data were simulated for each scan using a validated noise‐insertion method. Radiologists marked location and diagnosis for detected pathologies. Reference truth was obtained from the patient medical record, either from histology or subsequent imaging. Data Format and Usage Notes: Projection datasets were converted into the previously developed DICOM‐CT‐PD format, which is an extended DICOM format created to store CT projections and acquisition geometry in a nonproprietary format. Image data are stored in the standard DICOM image format and clinical data in a spreadsheet. Materials are provided to help investigators use the DICOM‐CT‐PD files, including a dictionary file, data reader, and user manual. The library is publicly available from The Cancer Imaging Archive (https://doi.org/10.7937/9npb‐2637). Potential Applications: This CT data library will facilitate the development and validation of new CT reconstruction and/or denoising algorithms, including those associated with machine learning or artificial intelligence. The provided clinical information allows evaluation of task‐based diagnostic performance. [ABSTRACT FROM AUTHOR]

Purpose: To compare radiation dose and image quality for abdominal CTs performed on a spectral detector CT (SDCT) and a comparable single-energy conventional CT scanner for patients of different sizes. Methods: Four semi-anthropomorphic phantoms were scanned on an SDCT (IQon, Philips Healthcare) and a comparable single-energy CT (iCT 256, Philips Healthcare) under matched scan parameters. Image noise and radiation dose were compared. For the HIPAA-compliant, IRB-approved retrospective cohort patient study, radiation dose was compared after adjusting for patient water equivalent diameter. Difference in subjective and objective image quality was assessed on a subset of 50 patients scanned on both scanners by two readers. Results: CTDIvol and noise from SDCT were higher than conventional CT for all phantoms, with a relative difference of 7.8% (range 5.3–14%) for radiation dose and average difference of 9.0% (range 5.5–11%) for noise. 718 SDCT and 937 conventional CT patients were included in the patient study. CTDIvol for SDCT patients tends to be lower for smaller patients (− 2%, 95% confidence interval (− 5%, − 0.2%) for 200 mm water equivalent diameter) and higher for larger patients compared to conventional CT (8%, (6%, 11%) for 400 mm). No difference was seen for subjective image quality, SNR, CNR, or image noise between the two scanners, except for higher image noise in the portal vein and higher signal in the aorta on SDCT. Conclusion: Radiation dose for abdominal CT performed on SDCT is similar to the dose on a conventional CT for average size patients, lower for smaller patients, and slightly higher for larger patients. Image quality is similar between the two scanners. [ABSTRACT FROM AUTHOR]

In x‐ray computed tomography (CT), materials with different elemental compositions can have identical CT number values, depending on the mass density of each material and the energy of the detected x‐ray beam. Differentiating and classifying different tissue types and contrast agents can thus be extremely challenging. In multienergy CT, one or more additional attenuation measurements are obtained at a second, third or more energy. This allows the differentiation of at least two materials. Commercial dual‐energy CT systems (only two energy measurements) are now available either using sequential acquisitions of low‐ and high‐tube potential scans, fast tube‐potential switching, beam filtration combined with spiral scanning, dual‐source, or dual‐layer detector approaches. The use of energy‐resolving, photon‐counting detectors is now being evaluated on research systems. Irrespective of the technological approach to data acquisition, all commercial multienergy CT systems circa 2020 provide dual‐energy data. Material decomposition algorithms are then used to identify specific materials according to their effective atomic number and/or to quantitate mass density. These algorithms are applied to either projection or image data. Since 2006, a number of clinical applications have been developed for commercial release, including those that automatically (a) remove the calcium signal from bony anatomy and/or calcified plaque; (b) create iodine concentration maps from contrast‐enhanced CT data and/or quantify absolute iodine concentration; (c) create virtual non‐contrast‐enhanced images from contrast‐enhanced scans; (d) identify perfused blood volume in lung parenchyma or the myocardium; and (e) characterize materials according to their elemental compositions, which can allow in vivo differentiation between uric acid and non‐uric acid urinary stones or uric acid (gout) or non‐uric acid (calcium pyrophosphate) deposits in articulating joints and surrounding tissues. In this report, the underlying physical principles of multienergy CT are reviewed and each of the current technical approaches are described. In addition, current and evolving clinical applications are introduced. Finally, the impact of multienergy CT technology on patient radiation dose is summarized. [ABSTRACT FROM AUTHOR]

Purpose: Water equivalent diameter (WED) is a robust patient‐size descriptor. Localizer‐based WED estimation is less sensitive to truncation errors resulting from limited field of view, and produces WED estimates at different locations within one localizer radiograph, prior to the initiation of axial scans. This method is considered difficult to implement by the clinical community due to the necessary calibration between localizer pixel values (LPV) and attenuation, and the unknown stability of calibration results across scanners and over time. We investigated the stability of calibration results across 25 computed tomography (CT) scanners from three medical centers, and their stability over 3 ∼ 29 months for 14 of those scanners. Methods: Localizer and axial images of ACR and body computed tomography dose index phantoms were acquired, using routine clinical techniques (120 kV and lateral localizers) on each of the 25 CT scanners: 8 GE scanners (CT750HD, VCT, and Revolution), 8 Siemens scanners (Definition AS, Force, Flash, and Edge), 5 Canon scanners (Aquilion‐One, Aquilion‐Prime80, and Aquilion‐64), and 4 Philips scanners (iCT 256, iQon, and Ingenuity). By associating axial images with the corresponding localizer lines, the relationship between the scaled water equivalent area (WEA) and averaged LPV were established through regression analysis. Results: Linear relationships between the scaled WEA and the averaged LPV were observed in all 25 CT scanners (R2>0.999). Calibration parameters were similar for CT scanners from the same vendor: the coefficients of variation (COV) were ≤ 1% in all four vendor groups for the calibration slope, and < 7% for the intercept. By analyzing the deviation of WED resulted from errors in the calibration slope or intercept alone, we derived the tolerance ranges for the slope or intercept for a given WED error level. The variation of slope and intercept from different CT scanners of the same vendor introduced <±2.5% error in the estimated WED for subjects of 20 and 30‐cm WED. The calibration parameters remained stable over time, with the maximum deviations all within the boundary values that introduce ±2.5% error in the estimated WED for subjects of 20 and 30‐cm WED. Conclusions: The stability in calibration results among CT scanners of the same vendor and over time demonstrated the feasibility of implementing WED estimation for routine clinical use. [ABSTRACT FROM AUTHOR]

Purpose: Water equivalent diameter (WED) is a robust patient‐size descriptor. Localizer‐based WED estimation is less sensitive to truncation errors resulting from limited field of view, and produces WED estimates at different locations within one localizer radiograph, prior to the initiation of axial scans. This method is considered difficult to implement by the clinical community due to the necessary calibration between localizer pixel values (LPV) and attenuation, and the unknown stability of calibration results across scanners and over time. We investigated the stability of calibration results across 25 computed tomography (CT) scanners from three medical centers, and their stability over 3 ∼ 29 months for 14 of those scanners. Methods: Localizer and axial images of ACR and body computed tomography dose index phantoms were acquired, using routine clinical techniques (120 kV and lateral localizers) on each of the 25 CT scanners: 8 GE scanners (CT750HD, VCT, and Revolution), 8 Siemens scanners (Definition AS, Force, Flash, and Edge), 5 Canon scanners (Aquilion‐One, Aquilion‐Prime80, and Aquilion‐64), and 4 Philips scanners (iCT 256, iQon, and Ingenuity). By associating axial images with the corresponding localizer lines, the relationship between the scaled water equivalent area (WEA) and averaged LPV were established through regression analysis. Results: Linear relationships between the scaled WEA and the averaged LPV were observed in all 25 CT scanners (R2>0.999). Calibration parameters were similar for CT scanners from the same vendor: the coefficients of variation (COV) were ≤ 1% in all four vendor groups for the calibration slope, and < 7% for the intercept. By analyzing the deviation of WED resulted from errors in the calibration slope or intercept alone, we derived the tolerance ranges for the slope or intercept for a given WED error level. The variation of slope and intercept from different CT scanners of the same vendor introduced <±2.5% error in the estimated WED for subjects of 20 and 30‐cm WED. The calibration parameters remained stable over time, with the maximum deviations all within the boundary values that introduce ±2.5% error in the estimated WED for subjects of 20 and 30‐cm WED. Conclusions: The stability in calibration results among CT scanners of the same vendor and over time demonstrated the feasibility of implementing WED estimation for routine clinical use. [ABSTRACT FROM AUTHOR]

Magnetization loss of high-temperature superconducting (HTS) wires is usually considered as a critical issue in power applications. In order to reduce magnetization loss, a narrow soldered-stacked-square (3S) HTS wire with 1 mm width is firstly proposed by our group. And as a novel HTS wire type, its magnetization loss should be significantly understood before applied in further application. In this study, we fabricate the 1-mm-wide 3S wires with 2+4c, 4+2c, and 6+0c structures, and evaluate their magnetization loss experimentally and numerically. In the fabrication process of the 3S wires, a newly suggested technology, laser cutting, is adopted. The results show that the magnetization loss in (4+2c)-wire is independent of the frequency under perpendicular field but dependent on the frequency under parallel field. This may be considered that both eddy current loss and coupling loss are contained in the case of parallel field, besides hysteresis loss. Moreover, the different structures of the 3S wires will not affect the magnetization loss under perpendicular fields, but influence the magnetization loss under parallel fields. And these numerical results for parallel field have larger deviations compared with measured magnetization loss because only hysteresis loss is considered in the numerical model. Finally, a considerable reduction of the magnetization loss in the 3S wire is observed in the comparison with that in the original tape. [ABSTRACT FROM AUTHOR]

The potential of utilizing shiitake mushroom as feed stock for the preparation of activated carbon by chemical activation method with K 2 CO 3 was explored. The prepared materials were characterized by thermogravimetric analysis, N 2 adsorption–desorption analysis, scanning electron microscope, Fourier transform infrared spectrometer, X-ray diffraction and Raman spectra. The activation mechanisms were proposed with the aid of thermogravimetric analysis. X-ray diffraction and Raman analysis indicated that the activated carbon was amorphous macroscopically. The influences of activation temperature, mass ratio of K 2 CO 3 /shiitake mushroom, activation duration, heating rate and material mixed mode on the yield, porosity and surface morphology of the activated carbon were investigated in detail. The synthesized activated carbons was predominantly microporous having a specific surface area of 2330 m 2 /g, and the optimal process conditions were activation temperature of 800 ∘ C, mass ratio of K 2 CO 3 /shiitake mushroom of 1.5, activation duration of 180 min, heating rate of 5 ∘ C/min and mixed mode of impregnation. Addition to high surface area, it also exhibited a high iodine number adsorption capacity of 1432 mg/g and methylene blue adsorption capacity of 872 mg/g, which are far higher than the adsorption capacities reported in the open literature. These results demonstrate that the synthesized activated carbon could be utilized for variety of industrial applications. [ABSTRACT FROM AUTHOR]

Purpose: Dual‐energy CT (DECT) has been shown to have a great potential in reducing the uncertainty in proton stopping power ratio (SPR) estimation, when compared to current standard method — the stoichiometric method based on single‐energy CT (SECT). However, a few recent studies indicated that imaging noise may have a substantial impact on the performance of the DECT‐based approach, especially at a high noise level. The goal of this study is to quantify the uncertainty in SPR and range estimation caused by noise in the DECT‐based approach under various conditions. Methods: Two widely referred parametric DECT methods were studied: the Hünemohr‐Saito (HS) method and the Bourque method. Both methods were calibrated using Gammex tissue substitute inserts scanned on the Siemens Force DECT scanner. An energy pair of 80 and 150 kVp with a tin filter was chosen to maximize the spectral separation. After calibrating the model with the Gammex phantom, CT numbers were synthesized using the density and elemental composition from ICRU 44 human tissues to be used as a reference, in order to evaluate the impact of noise alone while putting aside other sources of uncertainty. Gaussian noise was introduced to the reference CT numbers and its impact was measured with the difference between estimated SPR and its noiseless reference SPR. The uncertainty caused by noise was divided into two independent categories: shift of the mean SPR and variation of SPR. Their overall impact on range uncertainty was evaluated on homogeneous and heterogeneous tissue samples of various water equivalent path lengths (WEPL). Results: Due to the algorithms being nonlinear and/or having hard thresholds in the CT number to SPR mapping, noise in the CT numbers induced a shift in the mean SPR from its noiseless reference SPR. The degree of the mean shift was dependent on the algorithm and tissue type, but its impact on the SPR uncertainty was mostly small compared to the variation. All mean shifts observed in this study were within 0.5% at a noise level of 2%. The ratio of the influence of variation to mean shift was mostly greater than 1, indicating that variation more likely determined the uncertainty caused by noise. Overall, the range uncertainty (95th percentile) caused by noise was within 1.2% and 1.0% for soft and bone tissues, respectively, at 2% noise with 50 voxels. This value can be considered an upper limit as more voxels and lower noise level rapidly decreased the uncertainty. Conclusions: We have systematically evaluated the impact of noise to the DECT‐based SPR estimation and identified under various conditions that the variation caused by noise is the dominant uncertainty‐contributing component. We conclude that, based on the noise level and tumor depth, it is important to estimate and include the uncertainty due to noise in estimating the overall range uncertainty before implementing a small margin in the range of 1%. [ABSTRACT FROM AUTHOR]

Striated YBCO-coated conductor is a variant structure of the second-generation high-temperature superconducting (HTS) tapes. The ac loss is reduced owing to the YBCO layer of the striated YBCO tape is divided into filaments by laser scribing. Hence, it is promising for practical HTS electrical application, such as HTS transformer and cable. However, when the superconducting apparatuses are operated in the power grid, it will possibly experience the lightning impulse current in some extreme working condition. Thus, the performance of striated YBCO tapes suffering from exposure to lightning current is important to be studied. In this paper, a numerical model based on the electromagnetic–thermal coupling is built to analyze the lightning current performance of the striated YBCO tapes. The influence of structural changes on the thermal stability is discussed. The standard lightning current waveform is chosen, i.e., 8/20 μs. The simulated results show that cutting the copper edges of striated YBCO tapes will significantly degrade the lightning current withstand capacity. Instead, the degradation effect of grooves is not so obvious. [ABSTRACT FROM AUTHOR]

Narrowing high-temperature superconducting (HTS) tapes can effectively enhance the ability of antielectromagnetic interference. In addition, different structures of HTS wires are necessary for HTS applications. Thereby, a kind of soldered-stacked-square (3S) HTS Wires has been proposed. This paper presents a process of fabricating several 3S HTS wires. A normal second-generation (2G) HTS tape having 4-mm width was narrowed into four 1-mm-width narrow HTS tapes. The main propose of this paper is to study different effects of mechanical force on the critical current of 3S HTS wires. Therefore, we measured the critical current variation of these wires from the torsion, bending, and tension effects points of view, respectively. Compared with their initial critical current values, if the reduction of the influenced critical current is smaller than 5%, it can be considered that these 3S HTS wires are workable. Based on the results of the experiment, the limitations of mechanical force for these wire applications are: minimal twisting pitch of 64 mm, minimal bending diameter of 54 mm, and maximum tensile force of 374 N. [ABSTRACT FROM AUTHOR]

Angular dependence of second generation (2G) high-temperature superconducting (HTS) tape is a crucial parameter for its industrial applications. Known as soldered-stacked-square (3S) HTS wire, a novel structure of HTS wire has been proposed in our previous research. In this paper, angular dependence of 1 mm HTS tape, 4 mm tape, 1 mm 3S HTS wire, and 1 mm 3S HTS twisted wire were measured in liquid nitrogen bath, respectively. It can be found that the 3S HTS wire would not enhance the critical current density under external magnetic field, while an isotropic angular dependence is obtained when 3S HTS wire is twisted. The test results obtained in this paper provides useful information for the future applications of 3S HTS wire. [ABSTRACT FROM AUTHOR]

Magnetization loss is an important parameter in the design of high-temperature superconducting (HTS) power devices. It is produced under the external alternating magnetic fields. In previous work, for the purpose of reducing the loss, our group proposed and fabricated a novel soldered-stacked-square (3S) HTS wire with a cross-section of 1 mm × 1 mm. In this paper, the magnetization losses of the 3S wire are investigated numerically. First, numerical and theoretical losses in single HTS tapes are compared and their consistence proves the reliability of the numerical model. Also, the losses in tapes of different widths are evaluated, which shows the 1-mm tapes have less magnetization losses under perpendicular field. Moreover, the numerical model for estimating losses in 3S wires has also been built. According to a series of calculation and comparison, the 1-mm stacked wires have less losses than those wider stacked wires under perpendicular field. Besides, considering the practical application of HTS power devices, angular dependence of the loss in 3S wires containing one HTS tape is studied as well. The results indicate the loss increases with the increase of the angle with respect to the wire surface. [ABSTRACT FROM AUTHOR]

The feasibility of preparing glass ceramic from chambersite gravity tailings was explored. The crystallization parameters and state of glass ceramic were analyzed by Johnson-Mehl-Avrami and Augis-Bennett equations. The effects of sintering temperature and crystallization duration on bending strength and water absorption of glass ceramic were investigated, while the phase composition, crystal structure, lattice constants and surface topography were characterized. The results indicate the crystallization behavior of chambersite tailings glass ceramic is mainly body crystallization with clinopyroxene as a primary crystalline phase, the activation energy for crystallization (E) is 315.27 kJ/mol, the kinetics parameter for crystallization (k) is 7.98×1014, and the main phase lattice constants of clinopyroxene were a=0.97392 nm, b=0.88521 nm, c=0.52748 nm, β=107.062∘. At sintering temperature of 890 ∘C, pyroxene crystal with tetragonal column structure is formed, the diameter of the crystal is about 0.05-0.5 μm, while the crystallinity is more than 75%; the bending strength of the glass ceramic increases with the decrease in material particle size; at the D90 of 5.71 μm and crystallization duration of 150 min, the bending strength of glass ceramic reaches the maximum of 128.3 MPa and the water absorption is between 0.06 and 0.02%. [ABSTRACT FROM AUTHOR]

Purpose: To assess the non-inferiority of dual-layer spectral detector CT (SDCT) compared to dual-source dual-energy CT (dsDECT) in discriminating uric acid (UA) from non-UA stones.Methods: Fifty-seven extracted urinary calculi were placed in a cylindrical phantom in a water bath and scanned on a SDCT scanner (IQon, Philips Healthcare) and second- and third-generation dsDECT scanners (Somatom Flash and Force, Siemens Healthcare) under matched scan parameters. For SDCT data, conventional images and virtual monoenergetic reconstructions were created. A customized 3D growing region segmentation tool was used to segment each stone on a pixel-by-pixel basis for statistical analysis. Median virtual monoenergetic ratios (VMRs) of 40/200, 62/92, and 62/100 for each stone were recorded. For dsDECT data, dual-energy ratio (DER) for each stone was recorded from vendor-specific postprocessing software (Syngo Via) using the Kidney Stones Application. The clinical reference standard of X-ray diffraction analysis was used to assess non-inferiority. Area under the receiver-operating characteristic curve (AUC) was used to assess diagnostic performance of detecting UA stones.Results: Six pure UA, 47 pure calcium-based, 1 pure cystine, and 3 mixed struvite stones were scanned. All pure UA stones were correctly separated from non-UA stones using SDCT and dsDECT (AUC = 1). For UA stones, median VMR was 0.95-0.99 and DER 1.00-1.02. For non-UA stones, median VMR was 1.4-4.1 and DER 1.39-1.69.Conclusion: SDCT spectral reconstructions demonstrate similar performance to those of dsDECT in discriminating UA from non-UA stones in a phantom model. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the quantitative accuracy of spectral images from a detector‐based spectral CT scanner using a phantom with iodine‐loaded inserts. Methods: A 40‐cm long‐body phantom with seven iodine inserts (2–20 mg/ml of iodine) was used in the study. The inserts could be placed at 5.5 or 10.5 cm from the phantom axis. The phantom was scanned five times for each insert configuration using 120 kVp tube voltage. A set of iodine, virtual noncontrast, effective atomic number, and virtual monoenergetic spectral CT images were generated and measurements were made for all the iodine rods. Measured values were compared with reference values calculated from the chemical composition information provided by the phantom manufacturer. Radiation dose from the spectral CT was compared to a conventional CT using a CTDI (32 cm) phantom. Results: Good agreement between measurements and reference values was achieved for all types of spectral images. The differences ranged from −0.46 to 0.1 mg/ml for iodine concentration, −9.95 to 6.41 HU for virtual noncontrast images, 0.12 to 0.35 for effective Z images, and −17.7 to 55.7 HU for virtual monoenergetic images. For a similar CTDIvol, image noise from the conventional CT was 10% lower than the spectral CT. Conclusions: The detector‐based spectral CT can achieve accurate spectral measurements on iodine concentration, virtual non‐contrast images, effective atomic numbers, and virtual monoenergetic images. [ABSTRACT FROM AUTHOR]

Purpose: Lack of access to projection data from patient CT scans is a major limitation for development and validation of new reconstruction algorithms. To meet this critical need, this work developed and validated a vendor-neutral format for CT projection data, which will further be employed to build a library of patient projection data for public access. Methods: A digital imaging and communication in medicine (DICOM)-like format was created for CT projection data (CT-PD), named the DICOM-CT-PD format. The format stores attenuation information in the DICOM image data block and stores parameters necessary for reconstruction in the DICOM header under various tags (51 tags to store the geometry and scan parameters and 9 tags to store patient information). To validate the accuracy and completeness of the new format, CT projection data from helical scans of the ACR CT accreditation phantom were acquired from two clinical CT scanners (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany and Discovery CT750 HD, GE Healthcare, Waukesha, WI). After decoding (by the authors for Siemens, by the manufacturer for GE), the projection data were converted to the DICOM-CT-PD format. Off-line CT reconstructions were performed by internal and external reconstruction researchers using only the information stored in the DICOM-CT-PD files and the DICOM-CT-PD field definitions. Results: Compared with the commercially reconstructed CT images, the off-line reconstructed images created using the DICOM-CT-PD format are similar in terms of CT numbers (differences of 5 HU for the bone insert and -9 HU for the air insert), image noise (±1 HU), and low contrast detectability (6 mm rods visible in both). Because of different reconstruction approaches, slightly different in-plane and cross-plane high contrast spatial resolution were obtained compared to those reconstructed on the scanners (axial plane: GE off-line, 7 lp/cm; GE commercial, 7 lp/cm; Siemens off-line, 8 lp/cm; Siemens commercial, 7 lp/cm. Coronal plane: Siemens off-line, 6 lp/cm; Siemens commercial, 8 lp/cm). Conclusions: A vendor-neutral extended DICOM format has been developed that enables open sharing of CT projection data from third-generation CT scanners. Validation of the format showed that the geometric parameters and attenuation information in the DICOM-CT-PD file were correctly stored, could be retrieved with use of the provided instructions, and contained sufficient data for reconstruction of CT images that approximated those from the commercial scanner. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the ability of 100/Sn140 kV (Sn, tin filter) dual-energy computed tomography (CT) to differentiate urinary stone types in a patient cohort with a wide range of body sizes.Methods: Eighty human urinary stones were categorised into four groups (uric acid; cystine; struvite, oxalate and brushite together; and apatite) and imaged in 30-50-cm-wide water tanks using clinical 100/Sn140 kV protocols. The CT number ratio (CTR) between the low- and high-energy images was calculated. Thresholds for differentiating between stone groups were determined using receiver operating characteristics (ROC) analysis. Additionally, 86 stones from 66 patients were characterised using the size-adaptive CTR thresholds determined in the phantom study.Results: In phantoms, the area under the ROC curve for differentiating between stone groups ranged from 0.71 to 1.00, depending on phantom size. In patients, body width ranged from 28.5 to 50.0 cm, and 79.1 % of stones were correctly characterised. Sensitivity and specificity for correctly identifying the stone category were 100 % and 100 % (group 1), 100 % and 95.3 % (group 2), 85.7 % and 60.9 % (group 3), and 52.6 % and 92.5 % (group 4).Conclusion: Dual-energy CT can provide in vivo urinary stone characterisation for patients over a wide range of body sizes.Key Points: • Dual-energy CT helps assessment of urinary stone composition in vivo. • 100/Sn140 kV DECT differentiates among four stone types with 79.1 % accuracy. • In vivo diagnostic test achievable in patients with many body sizes. [ABSTRACT FROM AUTHOR]

Objective: To develop a dual-energy CT (DECT) method for differentiating uric acid (UA) from non-UA stones in the presence of iodinated contrast medium.Methods: Thirty UA and 45 non-UA stones were selected after infra-red spectroscopic analysis and independently placed in a 1.5-ml vial, which was filled first with saline and then with increasing concentrations of iodine. For each condition, tubes were put in a 35-cm water phantom and examined using a dual-source CT system at 100 and 140 kV. Virtual unenhanced images created from CT data sets of the stones in iodine-containing solutions provided position and volume information. This map was used to calculate a CT number ratio to differentiate stone type. A region-growing method was developed to improve the ability to differentiate between UA and non-UA stones with iodinated contrast medium.Results: The sensitivity for detecting UA stones was 100 % for unenhanced images but fell to 18 % with 20 mgI/ml iodine solution and 0 % for higher concentrations. With region growing, the sensitivity for detecting UA stones was increased to 100 %, 82 %, 57 %, 50 % and 21 % for iodine solutions of 20, 40, 60, 80 and 100 mgI/ml.Conclusion: The region-growing method improves differentiation of UA from non-UA stones on contrast-enhanced DECT urograms.Key Points: Computed tomography is widely used to assess renal tract calculi. Dual-energy CT can assess stone composition and provide virtual unenhanced images. However, iodinated contrast medium affects the volume estimation for urinary stones. CTR of stones is altered by the surrounding iodine in CT urograms. The region-growing method improves the identification of uric acid stones. [ABSTRACT FROM AUTHOR]

Purpose: For the purpose of size-specific dose estimation, information regarding patient attenuation is required. The purpose of this work is to describe a method for measuring patient attenuation and expressing the results in terms of a water cylinder, with cross sectional area Aw, which would absorb the same average dose as the irradiated patient. The ability to calculate Aw directly from the CT image was validated with Monte Carlo simulations and an analytical model. Methods: A series of virtual cylinders were created with diameters ranging from 10 to 40 cm and lengths of 40 cm. The cylinders were given an atomic number equal to that of water; the density of the cylinders was varied from 0.26 to 1.2 g/cm3. The average dose to the cylinders from an axial scan at the longitudinal center position was calculated using Monte Carlo simulation and an analytical model. The relationship between phantom cross sectional area and calculated dose was determined for each density value to determine the dependence of Aw on object attenuation. In addition, Aw was estimated from the virtual CT images based on two derived models expressing the potential dependence of Aw on object attenuation, one model assuming a linear dependence and the other assuming a quadratic dependence. Model results were compared with those from the Monte Carlo simulation and the analytical dose calculation approach. Virtual thorax and abdomen phantoms of adult and pediatric sizes were created, and Aw was estimated using geometrical size parameters or the derived models. The accuracy of each approach for estimating Aw was determined by comparing the average dose to the virtual phantom calculated using Monte Carlo simulation to the average dose to a water equivalent phantom of cross sectional area Aw. Results: In the absence of a bowtie filter, both the Monte Carlo simulation and analytical model showed that (Aw/A) had a quadratic dependence on (μ/μw). However, including a bowtie filter in the Monte Carlo simulation altered the relationship, such that Aw/A was linearly dependent on μ/μw. Using this relationship, the dose absorbed by a water cylinder of area Aw agreed with the dose absorbed by adult and pediatric, thorax and abdomen phantoms to within 6% (mean difference = 0.5 ± 4.8%). Estimates of Aw (or the water equivalent diameter Dw) using only anterior-posterior and lateral phantom dimensions led to dose estimates that agreed with Monte Carlo-derived dose values within 3% and 6% for the abdomen adult and pediatric phantoms, respectively. However, because of density differences between lung and tissue, larger differences in dose relative to Monte Carlo-derived values were observed in the thorax adult and pediatric phantoms (15% and 11%, respectively) when only geometrical parameters were used to estimate Dw. Conclusions: Patient attenuation can be quantified in terms of the diameter of a water cylinder that absorbs same average dose as the irradiated cross section of the patient. The linear dependence of Aw on object attenuation makes it straightforward to calculate Aw from a CT image on most operator consoles or clinical workstations. [ABSTRACT FROM AUTHOR]

Purpose: To estimate attenuation using cross sectional CT images and scanned projection radiograph (SPR) images in a series of thorax and abdomen phantoms. Methods: Attenuation was quantified in terms of a water cylinder with cross sectional area of Aw from both the CT and SPR images of abdomen and thorax phantoms, where Aw is the area of a water cylinder that would absorb the same dose as the specified phantom. SPR and axial CT images were acquired using a dual-source CT scanner operated at 120 kV in single-source mode. To use the SPR image for estimating Aw, the pixel values of a SPR image were calibrated to physical water attenuation using a series of water phantoms. Aw and the corresponding diameter Dw were calculated using the derived attenuation-based methods (from either CT or SPR image). Aw was also calculated using only geometrical dimensions of the phantoms (anterior-posterior and lateral dimensions or cross sectional area). Results: For abdomen phantoms, the geometry-based and attenuation-based methods gave similar results for Dw. Using only geometric parameters, an overestimation of Dw ranging from 4.3% to 21.5% was found for thorax phantoms. Results for Dw using the CT image and SPR based methods agreed with each other within 4% on average in both thorax and abdomen phantoms. Conclusions: Either the cross sectional CT or SPR images can be used to estimate patient attenuation in CT. Both are more accurate than use of only geometrical information for the task of quantifying patient attenuation. The SPR based method requires calibration of SPR pixel values to physical water attenuation and this calibration would be best performed by the scanner manufacturer. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this work was to evaluate dose performance and image quality in thoracic CT using three techniques to reduce dose to the breast: bismuth shielding, organ-based tube current modulation (TCM) and global tube current reduction. Methods: Semi-anthropomorphic thorax phantoms of four different sizes (15, 30, 35, and 40 cm lateral width) were used for dose measurement and image quality assessment. Four scans were performed on each phantom using 100 or 120 kV with a clinical CT scanner: (1) reference scan; (2) scan with bismuth breast shield of an appropriate thickness; (3) scan with organ-based TCM; and (4) scan with a global reduction in tube current chosen to match the dose reduction from bismuth shielding. Dose to the breast was measured with an ion chamber on the surface of the phantom. Image quality was evaluated by measuring the mean and standard deviation of CT numbers within the lung and heart regions. Results: Compared to the reference scan, dose to the breast region was decreased by about 21% for the 15-cm phantom with a pediatric (2-ply) shield and by about 37% for the 30, 35, and 40-cm phantoms with adult (4-ply) shields. Organ-based TCM decreased the dose by 12% for the 15-cm phantom, and 34-39% for the 30, 35, and 40-cm phantoms. Global lowering of the tube current reduced breast dose by 23% for the 15-cm phantom and 39% for the 30, 35, and 40-cm phantoms. In phantoms of all four sizes, image noise was increased in both the lung and heart regions with bismuth shielding. No significant increase in noise was observed with organ-based TCM. Decreasing tube current globally led to similar noise increases as bismuth shielding. Streak and beam hardening artifacts, and a resulting artifactual increase in CT numbers, were observed for scans with bismuth shields, but not for organ-based TCM or global tube current reduction. Conclusions: Organ-based TCM produces dose reduction to the breast similar to that achieved with bismuth shielding for both pediatric and adult phantoms. However, organ-based TCM does not affect image noise or CT number accuracy, both of which are adversely affected by bismuth shielding. Alternatively, globally decreasing the tube current can produce the same dose reduction to the breast as bismuth shielding, with a similar noise increase, yet without the streak artifacts and CT number errors caused by the bismuth shields. Moreover, globally decreasing the tube current reduces the dose to all tissues scanned, not simply to the breast. [ABSTRACT FROM AUTHOR]

Dual-energy computed tomography (DECT) allows one to obtain both density and atomic number and thus can provide information about material composition of scanned objects. In this paper, we extend a basis material decomposition method for high energy X-ray DECT used in cargo inspection. It differs from conventional DECT reconstruction methods by pair-production effect coming into play in the reconstruction. The pair-production does not happen for DECT in low energy level (lower than 1 MeV). The decomposition error of the basis material model and its applicability in the high-energy level are analyzed in this paper. A reconstruction method based on this model is proposed to reconstruct both the atomic number Z and the electron density \rhoe images for a high-energy DECT. The method is validated by a numerical simulation and a practical experiment on a cargo inspection system. Results show that the proposed reconstruction method is strongly grounded on physics and feasible for high-energy DECT in material discrimination, especially for cargo inspections. The advantages and limitations of the high-energy DECT, as well as possible improvements for future work are discussed in this paper. [ABSTRACT FROM AUTHOR]

Purpose: In diagnostic CT imaging, multiple important applications depend on the knowledge of the x-ray spectrum, including Monte Carlo dose calculations and dual-energy material decomposition analysis. Due to the high photon flux involved, it is difficult to directly measure spectra from the x-ray tube of a CT scanner. One potential method for indirect measurement involves estimating the spectrum from transmission measurements. The expectation maximization (EM) method is an accurate and robust method to solve this problem. In this article, this method was evaluated in a commercial CT scanner. Methods: Two step-wedges (polycarbonate and aluminum) were used to produce different attenuation levels. Transmission measurements were performed on the scanner and the measured data from the scanner were exported to an external computer to calculate the spectra. The EM method was applied to solve the equations that represent the attenuation processes of polychromatic x-ray photons. Estimated spectra were compared to the spectra simulated using a software provided by the manufacturer of the scanner. To test the accuracy of the spectra, a verification experiment was performed using a phantom containing different depths of water. The measured transmission data were compared to the transmission values calculated using the estimated spectra. Results: Spectra of 80, 100, 120, and 140 kVp from a dual-source CT scanner were estimated. The estimated and simulated spectra were well matched. The differences of mean energies were less than 1 keV. In the verification experiment, the measured and calculated transmission values were in excellent agreement. Conclusions: Spectrum estimation using transmission data and the EM method is a quantitatively accurate and robust technique to estimate the spectrum of a CT system. This method could benefit studies relying on accurate knowledge of the x-ray spectra from CT scanner. [ABSTRACT FROM AUTHOR]

An ideal animal model for hepatitis E virus (HEV) research is still unavailable. To assess the possibility of using Mongolian gerbils as animal model, 28 gerbils were randomly assigned into two groups, 14 for each group. Gerbils in Group 1 were inoculated with a genotype 4 HEV recovered from swine via the intraperitoneal route. Group 2 was used as a negative control and inoculated with normal suspension of swine liver. Sera and feces samples were collected once a week for 7 weeks. Two gerbils from both groups were necropsied weekly, pathological changes were recorded and tissue samples collected for further investigation. Distribution of the virus antigens was determined by immunohistochemical staining. Nested RT-PCR and a commercial ELISA kit were used to confirm the infection. Research results demonstrated that Mongolian gerbils in Group 1 were successfully infected with HEV. Viremia and fecal virus shedding lasted nearly 4 weeks, while the virus could be detected constantly in the liver, and occasionally in the kidneys and spleen as well as the small intestine. Histopathological changes in the liver were present with slight, multifocal, lymphohistiocytic infiltrates in the portal tracts or distributed irregularly throughout the liver. HEV antigens could be detected in the liver and intestine, and were mainly distributed in the nuclei. The results indicate that Mongolian gerbils could be used as an ideal animal model for the study of HEV. J. Med. Virol. 81:1591-1596, 2009. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]