X-ray Tube Research Articles

Pavlinsky Geliy Veniaminovich (1935–2023)

Pavlinsky Geliy Veniaminovich (1935–2023)

Noise Reduction Using Singular Value Decomposition with Jensen-Shannon Divergence for Coronary Computed Tomography Angiography.

Coronary computed tomography angiography (CCTA) is widely used due to its improvements in computed tomography (CT) diagnostic performance. Unlike other CT examinations, CCTA requires shorter rotation times of the X-ray tube, improving the temporal resolution and facilitating the imaging of the beating heart in a stationary state. However, reconstructed CT images, including those of the coronary arteries, contain insufficient X-ray photons and considerable noise. In this study, we introduce an image-processing technique for noise reduction using singular value decomposition (SVD) for CCTA images. The threshold of SVD was determined on the basis of minimization of Jensen-Shannon (JS) divergence. Experiments were performed with various numerical phantoms and varying levels of noise to reduce noise in clinical CCTA images using the determined threshold value. The numerical phantoms produced 10% higher-quality images than the conventional noise reduction method when compared on a quantitative SSIM basis. The threshold value determined by minimizing the JS-divergence was found to be useful for efficient noise reduction in actual clinical images, depending on the level of noise.

PEPI Lab: a flexible compact multi-modal setup for X-ray phase-contrast and spectral imaging

This paper presents a new flexible compact multi-modal imaging setup referred to as PEPI (Photon-counting Edge-illumination Phase-contrast imaging) Lab, which is based on the edge-illumination (EI) technique and a chromatic detector. The system enables both X-ray phase-contrast (XPCI) and spectral (XSI) imaging of samples on the centimeter scale. This work conceptually follows all the stages in its realization, from the design to the first imaging results. The setup can be operated in four different modes, i.e. photon-counting/conventional, spectral, double-mask EI, and single-mask EI, whereby the switch to any modality is fast, software controlled, and does not require any hardware modification or lengthy re-alignment procedures. The system specifications, ranging from the X-ray tube features to the mask material and aspect ratio, have been quantitatively studied and optimized through a dedicated Geant4 simulation platform, guiding the choice of the instrumentation. The realization of the imaging setup, both in terms of hardware and control software, is detailed and discussed with a focus on practical/experimental aspects. Flexibility and compactness (66 cm source-to-detector distance in EI) are ensured by dedicated motion stages, whereas spectral capabilities are enabled by the Pixirad-1/Pixie-III detector in combination with a tungsten anode X-ray source operating in the range 40–100 kVp. The stability of the system, when operated in EI, has been verified, and drifts leading to mask misalignment of less than 1 upmum have been measured over a period of 54 h. The first imaging results, one for each modality, demonstrate that the system fulfills its design requirements. Specifically, XSI tomographic images of an iodine-based phantom demonstrate the system’s quantitativeness and sensibility to concentrations in the order of a few mg/ml. Planar XPCI images of a carpenter bee specimen, both in single and double-mask modes, demonstrate that refraction sensitivity (below 0.6 upmurad in double-mask mode) is comparable with other XPCI systems based on microfocus sources. Phase CT capabilities have also been tested on a dedicated plastic phantom, where the phase channel yielded a 15-fold higher signal-to-noise ratio with respect to attenuation.

Operational optimization on large‐scale combined heat and power units with low‐pressure cylinder near‐zero output

AbstractMany power plants have been transformed and operated using low‐pressure cylinder near‐zero output (LP‐ZO) technology in China to make way for or provide necessary guarantees for renewable energy power generation. This research focuses on utilizing numerical simulation tools to improve the operational economy of units with LP‐ZO. The LP‐ZO thermodynamic and energy‐consumption model of a reference plant is established, and the momentum particle swarm optimization method is used to optimize the unit operations. Moreover, a model to determine the economic operational range of the combined heat and power plant with LP‐ZO is proposed. The results show that the LP‐ZO mode operations of the unit can reduce the minimum peak shaving rate and improve the flexibility of operations. The energy efficiency of the LP‐ZO mode is increased due to the recovery of a significant portion of the cold source losses. However, the irreversible exergy loss caused by large temperature difference heat exchange reduces the exergy efficiency of the unit. After operational optimization, the reference plant can save approximately 68.15 t d−1 of coal and reduce carbon dioxide emissions by about 27 t tce−1 d−1. This study provides an operating approach to the CHP plant with LP‐ZO unit in enhancing flexibility and economy.

A survey investigating postero-anterior chest X-ray clinical technique amongst radiographers and assistant practitioners in the UK: An extended pilot study

IntroductionWhilst many technical factors for the postero-anterior (PA) chest projection are well-researched and standardised, anecdotal evidence suggests a discrepancy regarding positioning of the X-ray tube; some radiographers using a horizontal tube, and others apply an angle. Currently there is a lack of published evidence supporting the benefits of either technique. MethodsFollowing University ethical approval, an invitation e-mail containing a link to a short questionnaire and participant information sheet was sent to radiographers and assistant practitioners in Liverpool and the surrounding areas, via professional networks/research team contacts. Questions related to length of experience, highest qualification and reasoned choice of horizontal versus angled tube preference in Computed Radiography (CR) and Digital Radiography (DR) rooms. The survey was open for nine weeks, with reminders at five and eight weeks. ResultsThere were 63 respondents. Both techniques were commonplace, with a non-statistically significant preference (p = 0.439) for a horizontal tube in both DR rooms (59%, n = 37) and CR rooms (52%, n = 30). Angled technique was employed by 41% (n = 26) of participants in DR rooms and 48% (n = 28) in CR rooms. Many participants indicated ‘taught’, or ‘protocol’, influenced their approach (46% [n = 29] in DR, 38% [n = 22] in CR). 35% (n = 10) of participants using caudal angulation, identified dose optimisation as the rationale in both CR and DR rooms. Most specifically noted reduced dose to the thyroid (69% [n = 11] in CR, 73% [n = 11] in DR). ConclusionsThere is evidence of variation in practice regarding horizontal versus an angled X-ray tube but no consistent rationale for either choice. Implications for practiceThere is a need to standardise tube positioning in PA chest radiography in line with future empirical research into the dose-optimisation implications of tube angulation.

Solar Energy powered active Greenhouse for the cultivation of Fresh Food during winter in Trans Himalayan Cold Arid Region, India

The Trans-Himalayan Cold arid high altitude region of Ladakh have hostile climatic conditions particularly lowtemperature (-20°C to -45°C). The region shares international borders with two countries viz. China and Pakistanand hence large numbers of Army personnel are deployed in the region due to their strategic importance. Production of fresh food locally is difficult due to low atmospheric temperatures. The region remains cut off from the external world during the winter period for almost 6-8 months due to the closure of roads, which causes an acute shortage of fresh food. Some supply from other regions through the air is carried out but available only to a limited population and costly also, hence beyond the pocket of the common’s man. The inhabitants hence mostly have to survive on packaged food containing food preservatives and harmful chemicals, which are the causes of many diseases. In addition, the unavailability of fresh food causes nutritional deficiency in the inhabitants of the region. Production of fresh food locally seems possible and realistic in closed structures, only if the temperature is maintained. The objective of this study is to prove fresh food production by maintaining suitable temperatures in structures during peak winter using solar energy. Solar energy is available in plenty in the region and stood at 4 th position in India in terms of irradiation. A variety of fresh foods were produced by maintaining temperature in the coldest and largest existing structure using commercially available heating units successively from 2016-2019 during the winter period. The heating units were supplied energy from a Solar PV-based system. An average of 1500kgs-1800kgs of a variety of fresh vegetables were produced and supplied for the first time in the region during the peak winter period of 2016 to 2019. The survival percentage of 92.5% to 100% is found in a structure with an area of 3600 2 feet.Fresh foods were produced and supplied to the user by maintaining minimum survival temperature using solar energy as a source with commercially available heating technology in the largest and coldest existing structure.

Impact of Heat Pump and Cogeneration Integration on Power Distribution Grids Based on Transition Scenarios for Heating in Urban Areas

Electrification of final use sectors such as heating and mobility is often proposed as an effective pathway towards decarbonization of urban areas. In this context, power-driven heat pumps (HP) are usually strongly fostered as alternatives to fossil-burning boilers in municipal planning processes. In continental climates, this leads to substantially increased electricity demand in winter months that, in turn may lead to stress situations on local power distribution grids. Hence, in parallel to the massive implementation of electric HP, strategies must be put in place to ensure the grid stability and operational security, notably in terms of voltage levels, as well as transformer and line’s capacity limits. In this paper, three such strategies are highlighted within the specific situation of a mid-sized Swiss city, potentially representative of many continental, central Europe urban zones as a test-case. The hourly-based power flow simulations of the medium- and low-voltage distribution grids show the impact of various future scenarios, inspired from typical territorial energy planning processes, implying various degrees of heat pumps penetration. The first strategy relies on the implementation of decentralized combined heat and power (CHP) units, fed by the existing natural gas network and is shown to provide an effective pathway to accommodate heat pump electricity demand on urban power distribution grids. Two alternative solutions based on grid reinforcements and controlled usage of reactive power from photovoltaic (PV) inverters are additionally considered to ensure security constraints of grid operation and compared with the scenario relying on CHP deployment.

Exploring the Impact of Regional Integrated Energy Systems Performance by Energy Storage Devices Based on a Bi-Level Dynamic Optimization Model

In the context of energy transformation, the importance of energy storage devices in regional integrated energy systems (RIESs) is becoming increasingly prominent. To explore the impact of energy storage devices on the design and operation of RIESs, this paper first establishes a bi-level dynamic optimization model with the total system cost as the optimization objective. The optimization model is used to optimize the design of three RIESs with different energy storage devices, including System 1 without an energy storage device, System 2 with a thermal energy storage (TES) device, and System 3 with TES and electrical energy storage (EES) devices. According to the design and operation results, the impact of energy storage devices on the operational performance of RIESs is analyzed. The results show that under the design conditions, energy storage devices can significantly increase the capacity of the combined heating and power units and absorption chillers in System 2 and System 3 and reduce the capacity of the ground source heat pumps and gas boilers; the impact of the TES device on System 3 is more significant. Affected by systems’ configuration, the operating cost, carbon tax, and total cost of System 2 are reduced by 2.9%, 5.5%, and 1.5% compared with System 1, respectively. The EES device can more significantly reduce the operating cost of System 3, with a reduced rate of 5.7% compared with that in System 1. However, the higher equipment cost makes the total cost reduction rate of System 3 less than that of System 1, which is 1.75%. Similar to the design conditions, under the operation conditions, the TES device can effectively reduce the carbon tax, operating cost, and total cost of System 2, while System 3 with an EES device can significantly reduce its operating cost regardless of whether the energy price changes or not. To some extent, this study systematically elucidated the impact of TES and EES devices on the optimal design and operation performance of RIESs and provided a certain reference for the configuration of energy storage devices.

A comparative study between pure bismuth/tungsten and the bismuth tungsten oxide for flexible shielding of gamma/X rays

Thermoplastic vulcanizate based flexible W/Bi and bismuth tungsten oxide composites with different doping ratios from 20% to 100% are successfully fabricated. The ray attenuation abilities of the composites are determined at X-ray tube voltages of 80 KVp–120 KVp, and at gamma rays of 59 keV, 122 keV, 343 keV and 960 keV. The surface morphology and elements mapping of W/Bi and bismuth tungsten oxide particles within the polymer have confirmed a more uniform dispersion of bismuth tungsten oxide than W/Bi. Shielding parameters such as transmittance T, mass/linear attenuation coefficients μm and μ, as well as lead equivalent δPb are investigated experimentally and numerically by Monte Carlo code NECP-MCX as well as XCOM program. The transmittance of γ ray decreases exponentially with the areal density of the functional particles, and the best shielding of X-ray goes to 100 KVp tube voltage, followed by 80 KVp and 120 KVp. A comparison of the two series of composites are made that W/Bi always has advantages over bismuth tungsten oxide in attenuation coefficients and lead equivalent, because the extra containing oxygen atoms in bismuth tungsten oxide crystal actually provide very weak additional shielding. Test of mechanical property also reflects the advantage of using pure W/Bi over bismuth tungsten oxide in flexibility. As substitutes for Pb containing materials, these two types of composites could be of potential use in medical diagnosis, interventional surgery, or biological radiation protection, etc.

Information Gap Decision Theory-Based Risk-Averse Scheduling of a Combined Heat and Power Hybrid Energy System

This research investigates the optimal management of electric and heat energies in a hybrid energy system (HES). In the studied HES, a pair of photovoltaic and battery storage devices is used to supply the electricity demand, and a boiler system to supply the heat demand directly. In addition, a modified cycle power plant acted as a combined heat and power (CHP) unit to increase the generation capacity and supply reliability. The HES is also able to connect to the electric grid to exchange power according to real-time energy prices. The uncertainty of renewable generation, demand levels, and energy prices challenge the decision-making process. To deal with the uncertainty of these overlapping parameters, a comprehensive information-gap decision theory (IGDT) approach is proposed in this paper that, despite other works, considers the uncertainties in an integrated framework and derives risk-averse and risk seeker strategies in different steps. The problem is modeled as mixed-integer linear programming and solved using the GAMS optimization package. Concerning simulation results, from the viewpoint of a risk-seeking decision maker, the increment of the uncertainty degree by 10.906% results in a reduced operating cost of 8.6%. From the viewpoint of a risk-averse decision maker, the increment of the uncertainty degree by 10.208% results in 8.6% more operating cost.

UVA-emitting composite film based on LaB3O6:Ce3+ phosphor for X-ray imaging

A series of UVA-emitting LaB3O6:Ce3+ phosphors and La0.96Ce0.04B3O6/PMMA films were prepared. The calcining temperature, activator concentration and PL test temperature were studied for the luminescence properties of the phosphor. And the effect of phosphor content on transmittance and X-ray radiation capacity of the composite films was also studied. The results show that LaB3O6:Ce3+ emits continuous double peaks at 358 nm and 380 nm when excited at 333 nm, the fluorescence lifetime is about 10 ns, and the luminescence intensity at 150 °C is 73.71% of that at room temperature, which can be used as phosphors for UV phototherapy applications. Under X-ray excitation, the integrated intensity of the La0.96Ce0.04B3O6/PMMA composite film has a good linear relationship with the X-ray tube current and tube voltage, and the X-ray imaging of a car key taken by La0.96Ce0.04B3O6/PMMA composite film has good signal-to-noise ratio, which can be used for X-ray detection and imaging.

Assessment of the dynamic thermal behaviour of a test room using computer simulations and experimental measurements

People spend most of the time indoors and adequate comfort level in buildings is fundamental for their well-being and productivity. These issues can be investigated using both simulation models and experimental measurements in dedicated laboratories or in real buildings. The numerical and experimental approaches need to be combined in order to overcome the limitations of each one. This paper presents the application of a detailed numerical model to the CORE-CARE laboratory built at the University of Padua, a test room employed for indoor environmental quality (IEQ) evaluations. The HVAC plant consists of a mechanical ventilation unit and radiant systems for space heating and cooling. Each radiant surface presents different constructive characteristics and can operate independently. The test room is a novelty in this panorama, as it was integrated in an existing building, as a room for regular use. The impossibility of controlling external disturbances makes the dynamic modelling of the room extremely important, for the laboratory control and knowledge. For this reason, the test room behaviour in response to different HVAC system settings and external disturbances is analysed. Two experimental campaigns were carried out both in the heating and cooling seasons, activating one surface at a time, in order to both validate the model and set-up the transient thermal behaviour of the laboratory. In summer, three experimental set-ups were arranged: closed blinds, opened blinds and presence of a thermal dummy. The data analysis highlights that the North surface exhibits the fastest response in both seasons, whereas the floor is the slowest due to its inertia. In summer, the active surface equilibrium temperature is closer to the water supply temperature for responsive and massive surfaces, and it rises with incoming solar radiation and thermal dummy heat gain. The cooled floor enhances the space's thermal stratification. Simulation results show that the model reproduces the system's real dynamics, with a maximum RMSE of 2.3 and 1.9 °C for the North surface and air temperature.

Intraoperative Fluoroscopy Radiation Using OEC 9900 Elite C-arm: Risk and Method for Decreasing Exposure.

The use of intraoperative fluoroscopy in surgery produces scattered radiation that can expose all operating room personnel to measurable and, in some cases, substantial radiation doses. The goal of this work is to assess and document potential radiation doses to various staff positions in a simulated standard operating room environment. Adult-sized mannequins wearing standard lead protective aprons were placed at seven positions around large and small BMI cadavers. Doses were recorded in real time at thyroid level with Bluetooth-enabled dosimeters for a variety of fluoroscope settings and imaging views. A total of 320 images were acquired, resulting in 2,240 dosimeter readings from the seven mannequins. Doses were compared to cumulative air kerma (CAK) calculations provided by the fluoroscope. There was a strong correlation between the CAK and the recorded scattered radiation doses ( P < 0.001). Radiation doses could be reduced by manipulating C-arm manual technique settings [e.g., turning off the automatic exposure control (AEC) and using pulse (PULSE) or low dose (LD) settings]. Staff position and patient size also affected the recorded doses. The highest radiation doses were recorded across all settings for the mannequin positioned immediately adjacent to the C-arm x-ray tube. The larger BMI cadaver generated greater scattered radiation than the smaller BMI cadaver for all views and settings. This work provides suggestions for reducing exposure to operating room personnel beyond standard techniques of reducing beam-on time, increasing the distance from the radiation source, and use of shielding. Simple changes in C-arm settings (turning AEC off, avoiding DS setting, use of PULSE or LD settings) can markedly reduce dose to staff.

Properties of ScAlMgO4 as Substrate for Nitride Semiconductors

SCAM has been expected to be a suitable substrate for GaN blue-light-emitting-diodes (LEDs) and high-power high electron mobility transistors (HEMTs) because of its lower lattice mismatch to GaN than that of the widely used sapphire. Considering both potential device applications, the crystal lattice and optical properties of SCAM substrates were investigated on selected high quality samples. As lattice parameters, the thermal expansion coefficient as well as the lattice constant were extrapolated from room temperature to 2000 °C by using a high temperature X-ray diffraction (XRD) system with the heating unit on a sample stage. The thermal conductance, which is also important for growing bulk SCAM crystals and the operation of devices on the SCAM substrate, was measured. Raman scattering measurements were carried out to better understand crystal lattice characteristics. It was clearly confirmed that prepared SCAM crystals were of high quality. Similar to sapphire, SCAM has the high transparency over the wide wavelength range from ultraviolet to mid-infrared. The refractive index, important for the design of any optical devices, was measured. From these results, it can be said that SCAM is a suitable substrate for nitride devices, especially LEDs and solar cells.

Optimal Scheduling of Combined Electric and Heating Considering the Control Process of CHP Unit and Electric Boiler

In order to solve the problem of new energy consumption, a combined electric and heating system (CEHS) dynamic optimal scheduling method considering the optimal control of combined heat and power (CHP) unit and electric boiler is proposed from the perspective of unit technology transformation, to optimize the thermoelectric coupling relationship and improve the regulation capacity of the CEHS. Firstly, the electric and heat output models of CHP units considering the optimal control process, were constructed and used to analyze the electric–thermal characteristics and the impact of unit pressure safety under variable load input. On this basis, CHP units, electric boilers, wind power units, and thermal power units are optimally scheduled to minimize system operating costs. Finally, a simultaneous method of “discrete first, optimize later” is proposed to solve the dynamic optimal scheduling problem. The simulation results verify that the optimal scheduling considering the optimal control of CHP units and the retrofitting of electric boilers can promote the consumption of wind power and improve the overall operating economy of the system while ensuring the feasibility of the CEHS scheduling scheme.

Application of multispectral computed tomography for the characterisation of natural graphite

The established mineralogical and chemical analysis methods for graphite ores require complex sample preparation. Moreover, they do not produce 3D images of the polymineralic rock structure and texture. The lack of 3D information can lead to an erroneous assessment of the quality-determining properties of graphite ores, such as graphite flake size (grain size), graphite flake size distribution, and impurities. Therefore, there is a need to obtain 3D information from graphite ores and concentrates. Industrial computed tomography (CT or single-spectrum CT) is a unique technique that enables the examination of rocks in the 3D regime. The challenge in CT analysis of ores is the different absorption properties of mineral phases present. Low X-ray tube generator voltages lead to pronounced artefacts (volume defects) if highly absorbing gangue phases (e.g. iron sulfides) are present. Therefore, high X-ray tube voltages must be applied. However, graphite and associated gangue minerals, as well as contained cracks and voids in the ore, can exhibit similar absorption properties at higher generator energies (above 120 kV). Multispectral CT (MSP-CT) measurements offer a minimisation of CT artefacts and an increase in grey value contrasts. This work investigates the application of the MSP-CT measurements, significantly improving mineral differentiation.

Modeling and control method of combined heat and power plant with integrated hot water storage tank

To enhance the flexibility of conventional power plants, a dynamic mathematical model of a combined heat and power unit is developed and verified in this study using field data, and the maximum relative error is less than 5%. Subsequently, the dynamic characteristics of the coal-fired power plant with the hot water storage tank are studied, and the temperature distribution curve inside the hot water storage tank is obtained. Finally, a new coordinated control system with an integrated hot water storage tank is designed. The new coordinated control system reduces the fluctuation in the heating load caused by the unit in the process of changing the load. The integral of absolute value of the error criterion and integral of time multiplied by the squared error criterion results for unit loads at different variable load rates are at least 200 and 50,000 lower compared to conventional control methods. This study provides a new solution to the problem that the current conventional turbine and boiler coordinated control system cannot address the difficulty of renewable energy power consumption, which is important for the safe and stable power grid operation after the large-scale grid connection of renewable energy power.

High Energy CT applications for cultural heritage

The application of computed tomography (CT) in the field of cultural heritage is no new concept and widely applied mainly by usage of medical or industrial CT systems. Nevertheless, CT setups based on conventional X-ray tubes with energy spectra up to 600 kV face several limitations considering the overall maximum specimen dimension due to the available foot print of the CT system and therefore scanning volume (approx. &lt; 1 m x 1 m x 1m), object weight (load limit of the manipulation system, usually &lt; 100 kg) and material properties, e.g. highly absorbing metal components. To overcome these boundaries High Energy CT systems with a linear accelerator (linac) radiation source with up to 9 MeV spectra prove to be a successful tool to push the limits of conventional CT and to provide a comprehensive extension for a new class of cultural heritage objects. In this paper, we demonstrate the beneficial application of high-energy photons for the digitization of historic objects and artifacts, as well as strategies for democratizing access to this still expensive but valuable technology for digital preservation, research and exhibition.

A study of off-focal radiation in transmission geometry x-ray sources

Off-focal x rays are an undesirable feature in industrial and medical x-ray computed-tomography scanners that contributes the effects of a large defocused source. They lead to artefacts in tomographic volumes that degrade contrast and resolution. A simple model of an x-ray tube with a transmission target has been developed in Topas, a Monte Carlo (MC) simulation extension to Geant4, to improve the understanding of the origin of off-focal x rays. From the analysis of the MC simulations we are able to identify the origin of various types of off-focal x rays and characterise their spatial distribution and energy spectra. We can then propose and test different mitigation methods, based both on hardware additions as well as improvements in the image reconstruction or data postprocessing.

CBCT Images to an STL Model: Exploring the "Critical Factors" to Binarization Thresholds in STL Data Creation.

In-house fabrication of three-dimensional (3D) models for medical use has become easier in recent years. Cone beam computed tomography (CBCT) images are increasingly used as source data for fabricating osseous 3D models. The creation of a 3D CAD model begins with the segmentation of hard and soft tissues of the DICOM images and the creation of an STL model; however, it can be difficult to determine the binarization threshold in CBCT images. In this study, how the different CBCT scanning and imaging conditions of two different CBCT scanners affect the determination of the binarization threshold was evaluated. The key to efficient STL creation through voxel intensity distribution analysis was then explored. It was found that determination of the binarization threshold is easy for image datasets with a large number of voxels, sharp peak shapes, and narrow intensity distributions. Although the intensity distribution of voxels varied greatly among the image datasets, it was difficult to find correlations between different X-ray tube currents or image reconstruction filters that explained the differences. The objective observation of voxel intensity distribution may contribute to the determination of the binarization threshold for 3D model creation.