Search

Background Purpose Methods Results Conclusions The permitted input power density of rotating anode x‐ray sources is limited by the performance of available target materials. The commonly used simplified formulas for the focal spot surface temperature ignore the tube voltage despite its variation in clinical practice. Improved modeling of electron transport and target erosion, as proposed in this work, improves the prediction of x‐ray output degradation by target erosion, the absolute x‐ray dose output and the quality of diagnostic imaging and orthovolt cancer therapy for a wide range of technique factors.Improved modeling of electronic power absorption to include volume effects and surface erosion, to improve the understanding of x‐ray output degradation, enhance the reliability of x‐ray tubes, and safely widen their fields of use.We combine Monte Carlo electron transport simulations, coupled thermoelasticity finite element modelling, erosion‐induced surface granularity, and the temperature dependence of thermophysical and thermomechanical target properties. A semi‐empirical thermomechanical criterion is proposed to predict the target erosion. We simulate the absorbed electronic power of an eroded tungsten‐rhenium target, mimicked by a flat target topped with a monolayer of spheres, and compare with a pristine target.The absorbed electronic power and with it the conversion efficiency varies with tube voltage and the state of erosion. With reference to 80 kV (100%), the absorption of a severely eroded relative to a pristine target is 105% (30 kV), 99% (100 kV), 97% (120 kV), 96% (150 kV), 93% (200 kV), 87% (250 kV), and 79% (300 kV). We show that, although the simplistic Müller–Oosterkamp model of surface heating underestimates the benefit of higher tube voltages relative to operation at 80 kV, the error is limited to below −6% for 30 kV (reduction advised) and +13% for 300 kV (input power increase permitted).Correcting the x‐ray conversion efficiency of eroded target material, that is typically not accessible by measuring the tube current, may imply corrections to existing x‐ray dose calculations. The relative increase of the allowable anode input power of rotating anode x‐ray tubes with increasing tube voltage is substantially smaller than predicted by volume heating models that only rely on the focal spot surface temperature. The widely used voltage agnostic Müller–Oosterkamp formalism fails to predict the tube voltage dependency of the surface temperature of rotating anode targets, ignores the temperature dependency of the thermal diffusivity of tungsten‐rhenium, and the granularity of the material. Nevertheless, we show theoretically why, backed by experience, the practical use of the Müller–Oosterkamp formalism is justified in medical imaging and provides a basis for comparison with new microparticle based targets. The reason for this surprising finding is that voltage dependent material erosion must be primarily considered as a precursor of thermal runaway effects. [ABSTRACT FROM AUTHOR]

The measurement of focal spot sizes in industrial x‐ray tubes using conventional edge and slit methods typically requires complex slit diaphragms and auxiliary testing equipment. Additionally, stringent spatial‐positioning requirements are imposed on the x‐ray tube, auxiliary testing equipment, and detector, making the machining of auxiliary testing equipment and meeting test conditions challenging. This study optimized and improved the auxiliary testing equipment and computations in the slit method based on the principles of the edge method. An experimental setup capable of self‐calibrating the spatial positions was designed, avoiding measurement errors during focal‐spot‐size measurements. We derived a formula for the focal spot size for this experimental setup, allowing measurements using slits of various sizes. Furthermore, we proposed a method for determining the focal spot size through linear fitting of multiple sets of slit dimensions and projected widths of the focal spot on the detector. This approach filters out random noise and errors during data collection, significantly enhancing measurement precision. By adjusting the slit and detector angles, we could measure the focal spot sizes at various angles and draw contour maps of the focal spot shape. This method was applied to measure the focal spot size and shape of a side‐window x‐ray tube under different voltage conditions. The overall measurement error was less than 6%, reflecting the reliability, accuracy, and consistency of the results obtained using the proposed method. Thus, the proposed method supports the inspection, verification, and maintenance of x‐ray sources. [ABSTRACT FROM AUTHOR]

X-ray communication is a kind of space communication technology which uses X-ray as information carrier. In order to improve the information transmission capacity, communication rate and anti-interference ability of X-ray communication, we proposes to design a novel multi-target X-ray source. The source is composed of a fast switching module of light channels based on FPGA technology and four photoelectric X-ray tubes with different target materials: Cr, Fe, Ni, and Cu. Using Geant4 software, we determined the optimal target thickness for each material, which enabled us to fully leverage the characteristic X-rays for multi-channel signal modulation transmission. Moreover, using CST software for particle trajectory simulation and optimization of the electron beam revealed that at a tube voltage of 20 kV, the focus area measures approximately 1.2 mm×1.2 mm. The simulations show that four kinds of spectra with high distinctiveness can be generated from the Cr, Fe, Ni, and Cu targets. Within a single modulation period, these spectra can be combined in various ways to create 16 different X-ray spectra signals, thereby increasing the number of communication elements and enhancing the information transmission rate. [ABSTRACT FROM AUTHOR]

As an alternative to rigid anodes, a novel concept of X-ray targets consisting of a stream or a multitude of streams of fast tungsten microparticles has recently been proposed. Low-density microparticle streams resemble thin targets with nearly constant intensity distribution over a wide range of photon energies, abruptly terminating at the Duane–Hunt limit of maximum photon energy instead of falling off smoothly. According to our simulations, fast microparticles outperform classical rigid targets and enable extremely high electronic input power density and X-ray output. This opens new possibilities for generating high-intensity, nearly monochromatic X-rays. Such keV-type X-ray sources could replace expensive electron synchrotrons in appropriate applications. Furthermore, for sufficiently thin microparticle streams, the output X-ray spectra are functions of particle size, allowing modulation of the mean photon energy. We simulated the spectral response of tungsten microparticles using Monte Carlo methods and confirmed the validity of our new concept to generate near-monochrome spectra and high intensity with microparticle-based X-ray sources, outperforming classical X-ray tubes. Furthermore, we confirm a weak size dependence of the mean energies of filtered X-rays. We complement previous results highlighting the advantages of microparticle-based X-ray targets and aim at the implementation of the new concept in the future. [ABSTRACT FROM AUTHOR]

The spatiotemporal resolution of diagnostic X-ray images obtained with rotating-anode X-ray tubes has remained limited as the development of rigid, high-performance target materials has slowed down. However, novel imaging techniques using finer detector pixels and orthovolt cancer therapy employing narrow X-ray focal spots demand improved output from brilliant keV X-ray sources. Since its advent in 1929, rotating-anode technology has become the greatest bottleneck to improvement. To overcome this limitation, the current authors have devised a novel X-ray generation technology based on tungsten microparticle targets. The current study investigated a hybrid solution of a stream of fast tungsten microparticles and a rotating anode to both harvest the benefits of the improved performance of the new solution and to reuse known technology. The rotating anode captures energy that may pass a partially opaque microparticle stream and thereby contributes to X-ray generation. With reference to fast-rotating anodes and a highly appreciated small focal spot of a standardized size of 0.3 for an 8° target angle (physical: 0.45 mm × 4.67 mm), we calculated a potential output gain of at least 85% for non-melting microparticles and of 124% if melting is envisioned. Microparticle charging can be remediated by electron backscattering and electron field emission. The adoption of such a solution enables substantially improved image resolution. [ABSTRACT FROM AUTHOR]

This study investigates the critical significance of anode material selection in defining the energy spectrum and properties of X-ray photons in medical physics applications. Using the GATE platform and Monte Carlo simulations, a direct relationship between anode material atomic number and photon fluence is demonstrated. As the atomic number increases from Z = 29 (Copper) to Z = 74 (Tungsten), photon fluence rises by 62 %, indicating a substantial impact on X-ray production. Furthermore, the X-ray spectrum is affected by this material-driven changes, revealing a noticeable shift towards higher energy values: the mean energy of the continuous spectrum rises from 46.97 keV for Copper to 49.0 keV for Tungsten. The thermal properties of the material affect the temperature increase at the focal point. Rhodium and Molybdenum have a higher temperature rise than Copper (Cu) and Tungsten (W), because Cu and W have a greater thermal diffusion compared to other materials. These findings underscore the significance of anode material choice in optimizing X-ray systems which may enhance diagnostic accuracy and efficiency in diverse applications. [ABSTRACT FROM AUTHOR]

The focal spot size of X-ray tube is one of the key factors affecting the imaging resolution, and it is also an important index to characterize the working performance of the X-ray source. Typically, after the X-ray tube is manufactured, the focal spot size must be measured and marked. Nowadays, the most widely used measurement standards for X-ray tube focal spot size in the world are IEC 60336, EN 12543, and ASTM E1165. Between various standards, there are differences in the focal spot size measurement methods, scope of application, loading factors and imaging equipment. Among these, the slit method of EN 12543 standard is mostly utilized in industrial X-ray tubes. However, due to its complex and precise design requirements, the test equipment, i.e., the slit camera, is difficult to produce and process, and the cost is high, which is not conducive to promotion and application. This paper studied the influence and variation of the measurement of the focal spot size at different slit sizes by using double tungsten alloy cylinders instead of slit camera. Based on the calibration of distance and position parameters in the cylinder method, the measurement equipment was conveniently positioned, and the distance between the focal spot and the translation mechanism was measured simultaneously, which improves the position accuracy of the focal spot size measurement. Additionally, the formula for determining the focal spot size in the slit method was improved, so that the slit method can be applied to a wide range of slit widths. In particular, the geometric magnification of the system can be measured directly when the slit width is large, skipping the step of measuring the distance between the focal spot and the translation mechanism. The experiment scheme has low requirements on the centering conditions of the equipment and the distribution of the X-ray source. In the data processing process, dark field correction and bright field correction were used to eliminate the problem of inconsistency in the response characteristics of each detector pixel, and the Wiener Filtering was performed on the signal output by the detector to deal with Gaussian noise and uniformly distributed noise. The experiment results show that relatively accurate measurement values can be obtained by measuring MXR-225HP/11 with double tungsten alloy cylinders with the same spacing as the focal spot size. The measurement relative error is less than 10%. According to international standards, when the measurement results are within plus or minus 10% of the theoretical value, it can be used as a method to determine the focal spot size. Therefore, the improved method in this paper is reliable and does not require high testing equipment, allowing it to be widely used. In addition, the geometric magnification of the focus measurement device can be directly calculated when the slit width is larger than the focal spot size, and the calculation results are consistent with the results measured in the cylinder method.

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an alternative to rigid anodes, a novel concept of X-ray targets consisting of a stream or a multitude of streams of fast tungsten microparticles has recently been proposed. Low-density microparticle streams resemble thin targets with nearly constant intensity distribution over a wide range of photon energies, abruptly terminating at the Duane–Hunt limit of maximum photon energy instead of falling off smoothly. According to our simulations, fast microparticles outperform classical rigid targets and enable extremely high electronic input power density and X-ray output. This opens new possibilities for generating high-intensity, nearly monochromatic X-rays. Such keV-type X-ray sources could replace expensive electron synchrotrons in appropriate applications. Furthermore, for sufficiently thin microparticle streams, the output X-ray spectra are functions of particle size, allowing modulation of the mean photon energy. We simulated the spectral response of tungsten microparticles using Monte Carlo methods and confirmed the validity of our new concept to generate near-monochrome spectra and high intensity with microparticle-based X-ray sources, outperforming classical X-ray tubes. Furthermore, we confirm a weak size dependence of the mean energies of filtered X-rays. We complement previous results highlighting the advantages of microparticle-based X-ray targets and aim at the implementation of the new concept in the future.

X-ray tube can easily produce X-ray, which is widely used in industry, archaeology and medicine. X-ray tubes use the interaction between high-speed electrons and anodic target atoms to generate X-rays, including discrete characteristic X-rays and continuous bremsstrahlung spectrum. Their spectral distribution is an important parameter index, which is the basis of subsequent applications. The spectral distribution can be obtained by actual measurement, Monte Carlo simulation and analytical calculation. Here, the analytical calculation of bremsstrahlung spectrum was mainly studied. Analytical calculation is to quickly calculate the bremsstrahlung spectrum produced by X-ray tube using known parameters. The key to its accuracy is the depth distribution of electrons in the anode target. By analyzing the depth distribution of electrons in the anode target, an analytical calculation model for the bremsstrahlung spectrum of electrons with incident energy from 10 to 50 keV in the copper target was established. Due to the elastic and inelastic interactions, the electron transport process in the target is very complex, and it is difficult to obtain the electron depth distribution by experimental or theoretical analysis. Monte Carlo simulation software Geant4 was used to simulate the interaction between the electron and copper target with incident energy of 10, 20, 30, 40 and 50 keV. The count, energy distribution and angle distribution of the electron at different penetration depths were obtained. The empirical formulas of electron depth distribution and path length correction coefficient of 10.50 keV electrons in copper target were obtained by fitting the simulated data. Since the penetration depth was scaled by using the continuous slowing down approximation range RCSDA, the parameters of the fitted empirical formula were approximately independent of the incident energy of electrons in this energy segment. The calculated results of the empirical formula for the electron depth distribution are in good agreement with the data of the electron depth distribution simulated by Geant4, which can accurately represent the electron depth distribution and the correction coefficient of path length. Combining the empirical formulas of electron depth distribution and path length correction coefficient with the corresponding bremsstrahlung cross-section data, an analytical calculation model of the bremsstrahlung spectrum of the thick target reflection type X-ray tube was established. Compared with Monte Carlo simulation results, the analytical calculation model has high accuracy and is in good agreement with the simulation results. When the electron incident energy is 15, 25, 35 and 45 keV, the spectral errors are 0.036 6, 0.041 7, 0.040 8 and 0.038 9, respectively. Compared with Monte Carlo simulation of X-ray tube bremsstrahlung spectrum, the analytical calculation speed is faster and can achieve high accuracy, which can be used in the need of fast calculation of X-ray tube bremsstrahlung spectrum.

The spatiotemporal resolution of diagnostic X-ray images obtained with rotating-anode X-ray tubes has remained limited as the development of rigid, high-performance target materials has slowed down. However, novel imaging techniques using finer detector pixels and orthovolt cancer therapy employing narrow X-ray focal spots demand improved output from brilliant keV X-ray sources. Since its advent in 1929, rotating-anode technology has become the greatest bottleneck to improvement. To overcome this limitation, the current authors have devised a novel X-ray generation technology based on tungsten microparticle targets. The current study investigated a hybrid solution of a stream of fast tungsten microparticles and a rotating anode to both harvest the benefits of the improved performance of the new solution and to reuse known technology. The rotating anode captures energy that may pass a partially opaque microparticle stream and thereby contributes to X-ray generation. With reference to fast-rotating anodes and a highly appreciated small focal spot of a standardized size of 0.3 for an 8° target angle (physical: 0.45 mm × 4.67 mm), we calculated a potential output gain of at least 85% for non-melting microparticles and of 124% if melting is envisioned. Microparticle charging can be remediated by electron backscattering and electron field emission. The adoption of such a solution enables substantially improved image resolution.

Main elements of the X-ray system of the Prometheus proton therapy complex are described. The system is integrated into the proton synchrotron outlet socket (exit cone), and allows X-ray micrographs and cone beam tomography of the patient body area of interest. The system is successfully used in clinical practice to verify the patient position immediately before irradiation. [ABSTRACT FROM AUTHOR]

The focal spot size of X-ray tube has great impact on the image quality in radiographic testing. Typical EN 12543 standard gives five measuring methods (scanning method, pinhole camera radiographic method, slit camera radiographic method, edge method and measurement of the effective focal spot size of mini and micro focus Xray tubes) for focal spot size of industrial Xray systems. The testing conditions and equipment of these methods are complicated except the edge method. However, the edge method cannot be used for an absolute measurement of the focal spot. It is only useful for the checking of focal spot under field condition in order to find change of the focal spot. Based on the edge method of EN 12543, an innovative method called cylinder method for the absolute measurement was proposed in this paper. This method was different from traditional measurement of the focal spot perpendicular to X-ray emission direction called nominal focus. It could measure the focal spot size at arbitrary angle within the field angle of radiation beam by using shift-rotation mechanism. In this experiment, the focal spot size of MXR-225HP/11 was measured by double tungsten alloy cylinder and 100 μm pixel areaarray detector. Double tungsten alloy cylinder could reduce the influence of scattering and the spacing between two cylinders was designed to be variable in preparation for future research on the silt camera radiographic method. Pixel areaarray detector overcame the shortcomings of film photography and was convenient for computer image processing. In order to improve the accuracy of measurement, a calibration method for measuring the distance parameter from the focal spot to the shiftrotation mechanism and location parameter at arbitrary angle was proposed. By measuring the large and small focal spot size of MXR225HP/11 at different angles in the width and length directions, it is found that the focal spot size varies with angle and nominal focus sizes agree well with those measured by pinhole camera radiographic method provided in the manual. However, the variation law of effective focal spot size with angle in the width direction is quite different from the theoretical analysis results, and the reasons need to be further explored. The results show this method can accurately measure the nominal focus size but also the focal spot size variation within the field angle of radiation beam which will provide reference for the design of focal spot and performance evaluation of Xray tube. Besides, the layout of imaging system can be optimized by the variation of focal spot size to ensure high imaging quality.

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The air kerma, which is the amount of energy given off by a radioactive substance, is essential for medical specialists who use radiation to diagnose cancer problems. The amount of energy that a photon has when it hits something can be described as the air kerma (the amount of energy that was deposited in the air when the photon passed through it). Radiation beam intensity is represented by this value. Hospital X-ray equipment has to account for the heel effect, which means that the borders of the picture obtain a lesser radiation dosage than the center, and that air kerma is not symmetrical. The voltage of the X-ray machine can also affect the uniformity of the radiation. This work presents a model-based approach to predict air kerma at various locations inside the radiation field of medical imaging instruments, making use of just a small number of measurements. Group Method of Data Handling (GMDH) neural networks are suggested for this purpose. Firstly, a medical X-ray tube was modeled using Monte Carlo N Particle (MCNP) code simulation algorithm. X-ray tubes and detectors make up medical X-ray CT imaging systems. An X-ray tube's electron filament, thin wire, and metal target produce a picture of the electrons' target. A small rectangular electron source modeled electron filaments. An electron source target was a thin, 19,290 kg/m3 tungsten cube in a tubular hoover chamber. The electron source–object axis of the simulation object is 20° from the vertical. For most medical X-ray imaging applications, the kerma of the air was calculated at a variety of discrete locations within the conical X-ray beam, providing an accurate data set for network training. Various locations were taken into account in the aforementioned voltages inside the radiation field as the input of the GMDH network. For diagnostic radiology applications, the trained GMDH model could determine the air kerma at any location in the X-ray field of view and for a wide range of X-ray tube voltages with a Mean Relative Error (MRE) of less than 0.25%. This study yielded the following results: (1) The heel effect is included when calculating air kerma. (2) Computing the air kerma using an artificial neural network trained with minimal data. (3) An artificial neural network quickly and reliably calculated air kerma. (4) Figuring out the air kerma for the operating voltage of medical tubes. The high accuracy of the trained neural network in determining air kerma guarantees the usability of the presented method in operational conditions. [ABSTRACT FROM AUTHOR]

Nowadays, there is a high demand to use radiation-based equipment to increase the precision of oil products monitoring systems. In this study, the application of X-ray tubes combined with feature extraction and artificial intelligence techniques were investigated for determining the volumetric percentages in two-phase flows. Firstly, a detection system consists of an X-ray tube, a horizontal Pyrex-glass pipe, and a NaI(TI) detector was simulated by MCNP code. Two flow regimes of annular and stratified were simulated in different volume percentages in the pipe. After acquiring the needed dataset using MCNP code, ten time-domain features were extracted from the dataset and then applied as the input of the neural network model of group method of data handling (GMDH). The GMDH neural network has the ability to diagnose the efficient input for achieving the best network configuration. Among extracted time characteristics of RMS, WL, ASS, MSR, ASM, average, STD, median, skewness, and kurtosis, GMDH neural network introduced the characteristics of RMS, ASS, MSR, ASM, and average as effective characteristics. Indeed, this GMDH neural network feature helped to determine effective characteristics for predicting volume percentages. The obtained predictions with a maximum root-mean-square error of 0.62 indicate that the use of the feature extraction methods is very applicable in determining volume percentages. [ABSTRACT FROM AUTHOR]

The effective focal spot size of x-ray tubes is one of the major factors that substantially affect the resultant x-ray images, and it is known to be dependent on the x-ray exposure setting used. This study aims to evaluate the relationship between the effective focal spot size and the tube current and voltage and assess its reproducibility among several x-ray tubes. The evaluation was performed using edge response analysis, in which a 1-mm thick tungsten edge was projected onto a flat panel detector with a magnification factor of 2. The edge image was then differentiated to obtain the line spread function, followed by a detector blur-removing process through Fourier analysis to obtain the true focus profile. The resultant focal spot size increased as the tube current increased, whereas it decreased as the tube voltage increased, as expected. The rate of change was similar along the width and the length directions, while the small focus changed more significantly than the large focus. The reproducibility among four x-ray tubes of the same model was excellent as the maximum variation < 20%. In conclusion, the edge response method can provide useful information on the x-ray focal spot relationship with the x-ray exposure settings used, as well as its reproducibility among several x-ray tubes. [ABSTRACT FROM AUTHOR]

Multi-target X-ray tube is a new type X-ray source, and can be applied in many fields such as sensitive X-ray fluorescence analysis and medical imaging. In this work, we report an electric field modulation multi-target X-ray tube, which contains four targets (Cr, Ni, Au, Mo) coated on a Beryllium (Be) window. A four-valve electric field deflector was developed to deflect the electron beam to bombard the corresponding targets. Particle dynamics analysis software was employed to simulate the particle tracking of electron beam. The results show that the 30 keV electron beam could get a 6.7 mm displacement on the target plane by 105 V/m electric field. The focus areas are about 2 mm × 5 mm and 4 mm × 2.5 mm after deflection in two directions. Thermal behavior calculated by ANSYS shows that the designed target assembly could withstand a 10 W continuous power. The optimum target thicknesses and emission spectra were obtained by Geant4 when the thickness of Be window was 300 μm and the electron beam incident angle was 0.141 rad. The results indicate that this multi-target X-ray tube could provide different X-ray sources effectively.

• New formula between FWHM and detector energy threshold was proposed at 100 kVp X-ray. • Cut-off frequency and sum of point spread function S(PSF) were computed. • Distinct and separate energy thresholds were considered to evaluate the PSF. • By detailed energy range and above 20 keV, FWHM converged to 220 mm and S(PSF) to 3026. • The suggested FWHM function may be used in structuring parameters of imaging devices. The response function of imaging systems is regularly considered to improve the qualified maps in various fields. More the accuracy of this function, the higher the quality of the images. In this study, a distinct analytical relationship between full-width at half-maximum (FWHM) value and detector energy thresholds at distinct tube peak voltage of 100 kV has been addressed in X-ray imaging. The outcomes indicate that the behavior of the function is exponential. The relevant cut-off frequency and summation of point spread function S(PSF) were assessed at large and detailed energy ranges. A compromise must be made between cut-off frequency and FWHM to determine the optimal model. By detailed energy range, the minimum and maximum of S(PSF) values were revealed at 20 keV and 48 keV, respectively, by 2979 and 3073. Although the maximum value of FWHM occurred at the energy of 48 keV by 224 mm, its minimum value was revealed at 62 keV by 217 mm. Generally, FWHM value converged to 220 mm and S(PSF) to 3026 with small fluctuations. Consequently, there is no need to increase the voltage of the X-ray tube after the energy threshold of 20 keV. The proposed FWHM function may be used in designing the setup of the imaging parameters in order to reduce the absorbed dose and obtain the final accurate maps using the related mathematical suggestions. [ABSTRACT FROM AUTHOR]

Monte Carlo simulation codes that model particle interactions with matter, including GEANT4, can be used to support the development of novel X-ray tubes and instruments for applications in industry and research. Based on our knowledge, simulations of the output of transmission-geometry X-ray tubes have not yet been conducted in GEANT4. Simulations of reflection-geometry tubes are scarce, with a limited number of studies investigating the capability and accuracy of GEANT4 in this domain. Therefore, the aim of this work is to benchmark GEANT4 for the characterisation of X-ray tubes with industry applications, using for the first time a range of X-ray tubes geometries and high voltages. In this work, GEANT4 is benchmarked against experimental measurements performed at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia, with both transmission and reflection X-ray tubes. High voltages between 17 kV and 42.5 kV for tungsten, molybdenum, gold, and silver targets are investigated. The measurements have been performed with a MXR packaged X-ray tube (reflection) and Magnum X-ray tubes (transmission) and a fast silicon drift detector (SDD). Our study shows that GEANT4 predicts the bremsstrahlung continuum output of transmission and reflection X-ray tubes, in agreement with the experimental measurements. The Penelope physics models, distributed with GEANT4, and the GEANT4 X-ray fluorescence data libraries ANSTO HF, based on the Hartree-Fock approach, exhibit the best agreement against experimental measurements. Depending on the high voltage, target and X-ray line agreement was found to vary between 10% and 300%. Differences between GEANT4 and experimental data are more significant for lower voltage X-ray tube measurements and are most likely due to limitations in the ionisation electron cross-section and/or atomic relaxation data libraries used. As next steps, it is recommended to validate GEANT4 against other, independent experimental measurements to corroborate the results of this work. In addition, it would be useful to repeat the same study with other general purpose Monte Carlo codes for radiation physics to compare their capability against GEANT4 in this application domain. • GEANT4 Monte Carlo simulations predict bremsstrahlung output of X-ray tubes. • Physics models in GEANT4 predict fluorescence intensity of X-ray tube differently. • Penelope and ANSTO HF models best reproduce experimental x-ray tube output. • Differences likely due to electron ionization cross-section or atomic relaxation. [ABSTRACT FROM AUTHOR]

The air kerma, which is the amount of energy given off by a radioactive substance, is essential for medical specialists who use radiation to diagnose cancer problems. The amount of energy that a photon has when it hits something can be described as the air kerma (the amount of energy that was deposited in the air when the photon passed through it). Radiation beam intensity is represented by this value. Hospital X-ray equipment has to account for the heel effect, which means that the borders of the picture obtain a lesser radiation dosage than the center, and that air kerma is not symmetrical. The voltage of the X-ray machine can also affect the uniformity of the radiation. This work presents a model-based approach to predict air kerma at various locations inside the radiation field of medical imaging instruments, making use of just a small number of measurements. Group Method of Data Handling (GMDH) neural networks are suggested for this purpose. Firstly, a medical X-ray tube was modeled using Monte Carlo N Particle (MCNP) code simulation algorithm. X-ray tubes and detectors make up medical X-ray CT imaging systems. An X-ray tube’s electron filament, thin wire, and metal target produce a picture of the electrons’ target. A small rectangular electron source modeled electron filaments. An electron source target was a thin, 19,290 kg/m3 tungsten cube in a tubular hoover chamber. The electron source–object axis of the simulation object is 20° from the vertical. For most medical X-ray imaging applications, the kerma of the air was calculated at a variety of discrete locations within the conical X-ray beam, providing an accurate data set for network training. Various locations were taken into account in the aforementioned voltages inside the radiation field as the input of the GMDH network. For diagnostic radiology applications, the trained GMDH model could determine the air kerma at any location in the X-ray field of view and for a wide range of X-ray tube voltages with a Mean Relative Error (MRE) of less than 0.25%. This study yielded the following results: (1) The heel effect is included when calculating air kerma. (2) Computing the air kerma using an artificial neural network trained with minimal data. (3) An artificial neural network quickly and reliably calculated air kerma. (4) Figuring out the air kerma for the operating voltage of medical tubes. The high accuracy of the trained neural network in determining air kerma guarantees the usability of the presented method in operational conditions.

The characteristic X-ray of a target is of considerable significance in industrial applications and medical diagnosis and treatment, and its intensity is closely related to the incident electron energy. At a high energy, it is not easy to determine the relation between characteristic X-rays and the incident electron energy through measurements, but the Monte Carlo method has a wide energy calculation range. In this study, the X-ray energy spectra of six target materials (Cu, Mo, Rh, Ag, W, and Pt) were simulated at various incident electron energies (<3 MeV) using the Monte Carlo code MCNP5 and the relation curve between the characteristic X-ray intensity of each of the target materials, and the incident electron energy was obtained through a simulation. A Si-PIN detector was used to measure the low-energy output energy spectra of two X-ray tubes (Ag and W targets). The relation curve between the X-ray tube excitation voltage and the characteristic X-ray intensity was obtained by fitting the measured data to a linear function. The simulation fitting curve and measurement fitting curve agreed well in the low-energy range. Comparisons of the calculated and measured values revealed that most of the deviations for the Ag target were less than 5%, and those for the W target were less than 6%. [ABSTRACT FROM AUTHOR]

We characterised the displacement of a transmission X-ray tube target parallel to the beam axis due to thermal effects using interferometry. Displacements of up to 10 μm with a sensitivity of about 0.4 μm/W deposited power were measured relative to the X-ray tube's mechanical mounting position. They significantly influence the scale factor of dimensional computed tomography measurements by several 10−4 at high geometric magnifications. Finite element simulations revealed that the displacement is due to thermal deformation of the entire target assembly and helped to derive a linearised model that predicted the displacements within a few tenths of a micrometre. Radiographic measurements of a calibrated standard confirmed that the mechanical displacement of the target corresponded with the X-ray focal spot position. The findings help to increase the accuracy of dimensional X-ray computed tomography measurements and to ameliorate the design of transmission X-ray tubes. [Display omitted] • Direct interferometric displacement measurement of an X-ray tube transmission target. • Finite element simulations revealed the underlying thermo-mechanical mechanisms. • A linearised model predicted the target position with sub-micrometre accuracy. • Confirmation by radiographic measurements of a calibrated standard. • Reduction of scale errors in high-magnification dimensional X-ray computed tomography by up to an order of magnitude. [ABSTRACT FROM AUTHOR]

Purpose: To present an x‐ray tube system capable of in vitro ultrahigh dose‐rate (UHDR) irradiation of small < 0.3 mm samples and to characterize it by means of a plastic scintillation detector (PSD). Methods and materials: A conventional x‐ray tube was modified for the delivery of short UHDR irradiations. A beam shutter system with a sample holder was designed and installed in a close proximity of an x‐ray tube window to enable <1 s irradiations at UHDR. The dosimetry was performed with a small 0.5‐mm long 0.5‐mm in diameter PSD irradiated with 80, 100, and 120 kVp beams and beam currents of 1–37.5 mA. The PSD signal was recorded at frame rates of 20 and 50 fps for shutter exposure between 100 and 1125 ms. Irradiation reproducibility was studied with the PSD. The x‐ray tube irradiation setup was modeled with Monte Carlo (MC) and dose on a surface of a phantom was also measured with films. The effect of dose delivery uncertainty to 300‐μm spheroids due to positioning and spheroid size was evaluated. Results: MC simulations showed good agreement with PSD measurements acquired at both frame rates of 20 and 50 fps in terms of beam temporal profile. PSD‐measured dose exhibited excellent linearity as a function of instantaneous dose rate from 3.1 to 118.0 Gy/s as well as shutter exposure time from 100 and 1125 ms for all investigated beam energies. PSD absorbed dose for the 80, 100, and 120 kVp beams agreed with MC simulations to within 5%. The total delivered doses ranged from 0.4 Gy for a 1‐mA, 80 kVp beam, and 100 ms shutter exposure to 166.9 Gy for a 37.5‐mA, 80 kVp beam, and a 1125 ms exposure. PSD irradiation reproducibility was < 0.5%. Simulated and measured dose fall off agreed and it was steep along the axis of the shutter slit (1%/0.1 mm) and with depth (2%/0.1 mm at 1‐mm depth). Spheroid positioning uncertainty of 300 μm resulted in dose difference of < 3% for x and y shifts but up to 7% uncertainty for a z‐shift parallel to the beam axis. A 16% difference in spheroid size resulted in <5% dose difference in spheroid absorbed dose. Conclusions: We have presented a cost‐effective x‐ray tube‐based system with a beam shutter designed for in vitro UHDR delivery and reaching dose rates of up to 118.0 Gy/s. The described shutter system can be easily implemented at other institutions, which might enable new researchers to investigate the radiobiology of UHDR irradiations in vitro. [ABSTRACT FROM AUTHOR]

Purpose: To develop a method to perform quality control (QC) of X‐ray tubes and automatic exposure control (AEC) as a part of the QC of the radiographic and fluoroscopic X‐ray system. Our aim is to verify the output from the X‐ray tube by comparing the measured radiation output, or air kerma, to the theoretical output given the applied exposure settings and geometry, in addition to comparing the measured kV to the nominal kV. The AEC system for fluoroscopic and conventional X‐ray systems is assessed by determining the absorbed dose to a homogenous phantom with different thicknesses. Method: This study presents a model to verify the X‐ray tube measurement results and a method to determine the dose to a homogenous phantom (Dphantom). The following input is needed: a parameterized model of the X‐ray spectrum, the X‐ray tube measurements using a multifunctional X‐ray meter, the exposure parameters recorded via imaging of polymethyl methacrylate (PMMA) slabs of different thickness that simulate the patient using AEC, and a parameterized model for calculating the dose to water from Monte Carlo simulations. The output is the entrance surface dose (ESD) and absorbed dose in the phantom, Dphantom (µGy). In addition, the parameterized X‐ray spectrum is used to compare theoretical and measured air kerma as a part of the QC of the X‐ray tube. To verify the proposed method, the X‐ray spectrum provided in this study, SPECTRUM, was compared to two commercially available spectra, SpekCalc and Institute of Physics and Engineering in Medicine (IPEM) 78. The fraction of energy imparted to the homogenous phantom was compared to the imparted fraction calculated by PCXMC. Results: The spectrum provided in this study was in good agreement with two previously published X‐ray spectra. The absolute percentage differences of the spectra varied from 0.05% to 3.9%, with an average of 1.4%, compared to SpekCalc. Similarly, the deviation from IPEM report 78 varied from 0.02% to 2.3%, with an average of 0.74%. The SPECTRUM was parameterized for calculation of the imparted fraction for target angles of 10°, 12°, and 15°, kV (50–150 kV) with the materials Al (2.2–8 mm), Cu (0–1 mm), and any combination of the filters, PMMA and water. The deviation of energy imparted from the results by PCXMC was less than 8% for all measurements across different kV, filtration, and vendors, obtained by using PMMA to record the exposure parameters, while the dose was calculated based on water with same thicknesses as the PMMA. Conclusion: This study presents an accurate and suitable method to perform a part of the QC of fluoroscopic and conventional X‐ray systems with respect to the X‐ray tube and the associated AEC system. The method is suitable for comparing protocols within and between systems via the absorbed dose. [ABSTRACT FROM AUTHOR]

• Mathematical equations are used to estimate the radiation output of the X-ray tubes. • Failure to consider all the parameters of the X-ray tube will distort the results. • kV, mAs, filtration, anode angle and ripple factor need to be considered. During any radiological procedure, it is important to know the dose to be-administered to the patient and this can be done by estimating the output of the X-ray tube either with a dosimeter or with a mathematical equation or Monte Carlo simulations. The aim of this work is to develop a new mathematical model equation (NMME) for estimating the output of high-frequency X-ray tubes. To achieve this, data collected from ten machines in many regions of Cameroon were used (for nine machines) to build an initial model that does not take into account the anode angle and the tenth machine was used to test the model. Using the SpekCalc software, some simulations were carried out to evaluate the influence of the anode angle. This allowed the NMME to be proposed. The deviations frequencies between 0.65% and 19.61% were obtained by comparing the output values obtained using initial model with the measured values. The statistical hypothesis test showed that the estimated values using initial model and NMME are in agreement with those measured unlike the Kothan and Tungjai model. For the tenth machine, the percentage difference between estimated and measured values is less than 8 %. These results show that the proposed model performed better than the previous models. In the absence of a dosimeter, the NMME could be used to estimate the output of high frequency X-ray machines and therefore the radiation doses received by patients during diagnostic X-ray examinations. [ABSTRACT FROM AUTHOR]

Near background low dose rate measurements are important part of the environmental radiation monitoring. It is possible to fulfill energy response verification for the high sensitive dosimeters based on inorganic scintillation detectors in low energy region when creating reference X-ray fields with dose rates up to 5 µSv/h. The aim of this work was to create and study reference X-ray fields with low dose rate and narrow spectrum in the energy range from 15 to 250 keV using high-purity metal filters as a part of X-ray irradiator of AT300 X-ray calibration facility.To determine the main characteristics of created X-ray fields highly sensitive comparators of photon radiation based on NaI(Tl) scintillation detectors was used. The comparators were developed in “ATOMTEX”. To verify comparators energy response the reference AT5350/1 dosimeter and ionization chamber TM32003 with sensitive volume 10000 cm3 were used.Characteristics of X-ray fields that were created on the AT300 X-ray calibration facility to verify the energy response of high sensitive dosimeters based on scintillation detectors were investigated. The possibility to calibrate high sensitive dosimetric measuring instruments based on scintillation detectors in the energy range up to 250 keV in X-ray beams was shown.

Two phase flows are of particular importance in various research fields. In the current article, a novel system consists of an X-ray tube and one sodium iodide crystal detector with ability of determining type of flow regime as well as void fraction percentage of a two phase flow, is proposed. MCNP-X code was used for physical modelling of the proposed system and its performance. Radial basis function (RBF) was also implemented for analyzing and classifying the obtained data from the proposed system. Counts in each 1 keV energy bin of photon energy spectra in the detector were inserted in RBF as inputs data set and flow regime and void fraction percentage were obtained as the two outputs. After training the RBF network, the system could simultaneously recognize all the flow regimes and predict the void fraction percentage of a modelled liquid–gas two-phase flow with an acceptable error. The proposed methodology in the present paper has three main novelties and advantages over former studies. Firstly, in this system an X-ray tube is used compared to previous studies where one or more radioisotope sources served as radiation source in a radiation based multi-phase flow meter. Secondly, in former works at least two detectors were used to recognize type of flow pattern and meter volume fractions simultaneously, while in this study only one detector is utilized. Thirdly, in this study just one neural network is used, while in other studies more than one network was used. [ABSTRACT FROM AUTHOR]

Purpose: Correlation of characteristic surface appearance and surface roughness with measured air kerma (kinetic energy released in air) reduction of tungsten‐rhenium (WRe) stationary anode surfaces. Methods: A stationary anode test system was developed and used to alter nine initially ground sample surfaces through thermal cycling at high temperatures. A geometrical model based on high resolution surface data was implemented to correlate the measured reduction of the air kerma rate with the changing surface appearance of the samples. In addition to the nine thermally cycled samples, three samples received synthetic surface structuring to prove the applicability of the model to nonconventional surface alterations. Representative surface data and surface roughness values were acquired by laser scanning confocal microscopy. Results: After thermal cycling in the stationary anode test system, the samples showed surface features comparable to rotating anodes after long‐time operation. The established model enables the appearance of characteristic surface features like crack networks, pitting, and local melting to be linked to the local x‐ray output at 100 kV tube voltage ,10° anode take off angle and 2 mm of added Al filtration. The results from the conducted air kerma measurements were compared to the predicted total x‐ray output reduction from the geometrical model and show, on average, less than 10 % error within the 12 tested samples. In certain boundaries, the calculated surface roughness Ra showed a linear correlation with the measured air kerma reduction when samples were having comparable damaging characteristics and similar operation parameters. The orientation of the surface features had a strong impact on the measured air kerma rate which was shown by testing synthetically structured surfaces. Conclusions: The geometrical model used herein considers and describes the effect of individual surface features on the x‐ray output. In close boundaries arithmetic surface roughness Ra was found to be a useful characteristic value on estimating the effect of surface damage on total x‐ray output. [ABSTRACT FROM AUTHOR]

The use of field emission cathodes in X-ray tubes requires the placement of the cathode assembly with a small gap from the anode, and this hampers the output of radiation. The greatest difficulties arise in the generation of a relatively soft spectrum with wavelengths of 1–10 nm: in this case, the accelerating voltage does not exceed several kilovolts and the interelectrode gap does not exceed several hundred microns. In this work, the possibility of using submicron films based on beryllium as through-type anodes for emitting the BeKα line (λ = 11.4 nm) and the accompanying bremsstrahlung spectrum is experimentally demonstrated. In particular, the characteristic radiation of a tube with a field emission blade-type cathode and a Be-film anode, introduced into a grazing incidence grating spectrometer, was detected. The characteristics of beryllium films necessary for designing high-power X-ray tubes of this type are determined. [ABSTRACT FROM AUTHOR]

• Monte Carlo simulations of kV X-ray tube was conducted that included scatter and off-focal radiation. • A statistical analysis of the photon components (energy, position, direction) was performed and presented. • Statistically based linear transforms (PCA, ZCA, ICA) were investigated for decoupling components. • A compact method of representing the X-ray source data that reduced memory requirements by a factor over 3 was devised. Monte Carlo (MC) simulations are a powerful tool for improving image quality in X-ray based imaging modalities. An accurate X-ray source model is essential to MC modeling for CBCT but can be difficult to implement on a GPU while maintaining efficiency and memory limitations. A statistical analysis of the photon distribution from a MC X-ray tube simulation is conducted in hopes of building a compact source model. MC simulations of an X-ray tube were carried out using BEAMnrc. The resulting photons were sorted into four categories: primary, scatter, off-focal radiation (OFR), and both (scatter and OFR). A statistical analysis of the photon components (energy, position, direction) was completed. A novel method for a compact (memory efficient) representation of the PHSP data was implemented and tested using different statistical based linear transformations (PCA, ZCA, ICA), as well as a geometrical transformation. The statistical analysis showed all photon groupings had strong correlations between position and direction, with the largest correlation in the primary data. The novel method was successful in compactly representing the primary (error < 2%) and scatter (error < 6%) photon groupings by reducing the component correlations. Statistical linear transforms provide a method of reducing the memory required to accurately simulate an X-ray source in a GPU MC system. If all photon types are required, the proposed method reduces the memory requirements by 3.8 times. When only primary and scatter data is needed, the memory requirement is reduced from gigabytes to kilobytes. [ABSTRACT FROM AUTHOR]

We have stabilized and equalized field-emission (FE) currents from carbon nanotube (CNT) emitters by a cascade active-current-control (ACC) using two transistors. Theoretical and experimental analyses on the cascade ACC operation, including single ACC with a single transistor, were done for both diode- and triode-configured CNT emitters. A fully vacuum-sealed CNT FE X-ray tube (FEXT) was used as a triode-configured test device. FE currents, in both configurations, by the cascade ACC were found to be stabilized to a standard deviation of 0.05% even in high-voltage and high-power circumstances while the single ACC could hardly regulate fluctuations in FE currents from CNT emitters. Furthermore, an array of CNT FEXTs successfully demonstrated a completely equalized emission current when the cascade ACC was employed. This result has important implications for FEXT current uniformity and other FEXTs applications, because the cascade ACC can equalize FE currents even through large variation of CNT emitters, thereby greatly enhancing the usability of FE devices. [ABSTRACT FROM AUTHOR]

To determine the dose given to patients in mammography, it is necessary to evaluate the mean glandular dose (MGD) in the computed radiography (CR) system with a solid-state detector, utilizing polymethyl methacrylate (PMMA) phantoms and spacers to model breast thickness. In the present study, irradiations were performed in a mammograph with a solid-state detector, and simulations were carried out using the Monte Carlo N-Particle Extended (MCNPX) code to give the MGD and spectra for the same conditions. In the mammograph, the glandular dose values were calculated for three anode/filter combinations: molybdenum/molybdenum (Mo/Mo), molybdenum/rhodium (Mo/Rh), and rhodium/rhodium (Rh/Rh). Through acquisitions from kerma values, the spectra were plotted. The MGD results obtained from the mammograph for Mo/Mo, Mo/Rh, and Rh/Rh were below the reported acceptable levels, while the spectra were mostly in accordance with the literature. • The average linear attenuation coefficient (μ) in the PMMA phantoms and spacers using points of interest. • In MCNPX, the tallies to be used for the photon fluency, the forced collision and photon physics. • Modeling some equipments in Vised. • Half-Value Layer, kerma and MGD measured in the mammograph with a solid-state detector for some anode/filter combinations. • MGD and spectra obtained in the MCNPX code. [ABSTRACT FROM AUTHOR]

BackgroundAs a hot material, diamond has been widely used in various civil and military equipment with high hardness (Mohs hardness is 10), compressive strength (greater than 1.2 GPa), excellent thermal (thermal conductivity at room temperature is 20~22 W·cm-1·K-1, thermal expansion coefficient at room temperature is only (1.1~1.3)×10-6 K-1), optical (higher transparency to X-rays) and electrical properties. Traditional optical window material beryllium is harmful to the human body and industrial hazards, its hardness, thermal conductivity and the thermal expansion coefficient are much lower than that of diamond.PurposeThis study aims to explore the performance of micro X-ray tube with diamond optical window by simulation, obtain the best thickness of diamond for X-ray tube optical window and its shielding effect against low, medium and high energy X-ray.MethodsThe Monte Carlo method was used to calculate the effective transmission ratio, peak back ratio and transmission ratio of characteristic X rays with diamond optical window in high energy region. The X-ray tube with 50 kV tube voltage and 1.0 mA tube current was taken as an example to determine the optimal thickness of diamond.ResultsSimulation results show that the Kα characteristic X-ray effective transmittance and peak to total X-ray ratio of the silver target increase continuously with the increase of the diamond window thickness, and the optimum diamond thickness is 2.0 mm. Under the optimal thickness of 2.0 mm, the effective transmittance is 154.5%, high-energy X-ray transmittance is 74.5%, and the characteristic X-ray peak back ratio is 27.9%.ConclusionsDiamond can be used as a substitute for beryllium optical windows and has good application prospect.

In this paper, the feasibility of using an X-ray tube instead of radioisotope sources for measuring volume fractions of gas, oil, and water in two typical flow regimes of three-phase flows, namely, annular and stratified, is evaluated. This study’s proposed detection system is composed of an X-ray tube, a 1 inch × 1 inch NaI detector, and one Pyrex-glass pipe to model different volume fractions for two flow regimes, annular and stratified. Group method of data handling (GMDH), a powerful regression tool, was also implemented to analyze the obtained data. The obtained results in this work indicate that a simple system based on an X-ray tube and just one NaI detector could be a potential alternative to radioisotope-based systems for separate measurements of gas, oil, and water volume fractions in annular and stratified flow regimes of a three-phase flow.

Purpose: By means of Monte Carlo (MC) simulations and indirect measurements, we have evaluated the maximum dose rates achievable with conventional x‐ray tubes and related them to FLASH therapy dose rates of >40 Gy/s. Methods: Monte Carlo models of two 160 kV x‐ray tubes, the 3‐kW MXR‐160/22 and the 6‐kW MXR‐165, were built in the EGSnrc/BEAMnrc code. The dose rate in a water phantom placed against the x‐ray tube surface, located at 3.7 and 3.5 cm from the focal spot for the MXR‐160/22 and MXR‐165 x‐ray tube, respectively, was calculated with DOSXYZnrc. Dose delivered with the 120‐kV beam in a plastic water phantom for the MXR‐160/22 was measured and calculated. Gafchromic EBT3 films were placed at 15 and 18 mm depths in the plastic water phantom that was irradiated with a low tube current of 0.2 mA for 30 s. Results: The maximum 160‐kV phantom surface dose rate was determined to be FLASH capable, calculated as (114.3 ± 0.6) Gy/s and (160.0 ± 0.8) Gy/s for the MXR‐160/22 and MXR‐165 x‐ray tubes, respectively. The dose rate in a 1‐cm diameter region was found to be (110.6 ± 2.8) Gy/s and (151.9 ± 2.6) Gy/s and remained FLASH capable to depths of 1.4 and 2.0 mm for the MXR‐160/22 and MXR‐165 x‐ray tube, respectively. The 120‐kV dose profiles measured with EBT3 films agreed with MC simulations to within 3.6% for regions outside of heel effect and at both measurement depths; this presented a good validation data set for the simulations of phantom surface dose rate using the 160‐kV beam. Conclusions: We have indirectly determined that, with a careful experimental design, conventional x‐ray tubes can be made suitable for use in FLASH radiotherapy and dosimetry experiments. [ABSTRACT FROM AUTHOR]

A complete virtual simulation experiment scheme for the micro-focus field emission electron gun based on the X-ray tube is proposed. A computer simulation software OPERA-3D is used to model the structure of the electron gun, and the effects of the gate shape, grid voltage, grid-focus distance and focus shape on the beam current and spot are studied. The optimized simulation results meet the design requirements. Through this simulation experiment, students can understand the basic principles of electron emission and the theory of electronic optics deeply, laying the foundation for studying related professional courses in the future. [ABSTRACT FROM AUTHOR]

Effect of a simultaneous thermal treatment at 480°C and X-ray radiation (irradiation dose 10−3 C/kg (∼4 R) in a vacuum (residual pressure 10−3 Pa) on the structure and properties of titanium oxide nanocoatings of various thicknesses, synthesized by the molecular layering technology on the inner surface of glass bulbs of X-ray tubes, was examined. It was shown that the thermal and X-ray radiation treatments in a vacuum lead to a recrystallization of the titanium oxide layer and removal of oxygen atoms from its composition, which affects the electrical properties of the system. [ABSTRACT FROM AUTHOR]

The air kinetic energy released per unit of mass (air kerma) quantity is of importance in both medicine and industry for evaluating the radiation field of X-ray tubes and also for calibrating the reference instruments. The air kerma spatial distribution inside the X-ray tube's radiation field is not uniform because of the heel effect phenomenon. In this paper, a combination of Monte Carlo N Particle eXtended (MCNPX) simulation code and artificial neural network (ANN) has been utilized to estimate the air kerma inside the radiation field of X-ray tube for a wide range of tube voltages (50–600 kV) which covers both medical and industrial applications. At first, an X-ray tube with an anode angle of 20° was simulated using MCNPX code. Next, in order to provide the required data for training the network, 1375 point detectors were placed in different positions inside the conical radiation field of the simulated X-ray tube and then the air kerma was calculated for tube voltages in the range of 50–600 kV with a step of 50 kV. The tube voltage and point detector's spherical coordinates including distance from target, tangential angle and polar angle were utilized as the 4 inputs and the air kerma was used as the output of the ANN. After training the ANN, the proposed ANN model could estimate the air kerma in every position inside the radiation field of X-ray tube for a wide range of voltages (50–600 kV) with a mean relative error (MRE) of less than 0.67%. • MCNPX and ANN were utilized to estimate the air kerma inside the radiation field of X-ray tube. • 1375 point detectors were placed inside the conical radiation field of the X-ray tube and then air kerma was calculated. • The tube voltage and point detector's spherical coordinates were utilized as the 4 inputs of the ANN. • The proposed ANN model could estimate the air kerma with a MRE of less than 0.67 %. [ABSTRACT FROM AUTHOR]

For real-time computed tomography (CT), a temporal resolution lower than 30 ms is required, which cannot be delivered by conventional CT architectures with a rotation gantry. Stationary CT architecture can achieve a temporal resolution lower than 30 ms by eliminating the physical rotation of the gantry and by electronically sweeping X-ray beams across the gantry. Stationary CT architecture utilizes two separate arrays, one for distributed X-ray sources and another for detectors. These individual X-ray sources are required to be compact, fast, and individually addressable in order to acquire 200+ projections for successful CT reconstruction and to achieve a temporal resolution lower than 30 ms. A compact X-ray tube that fits these requirements is being developed. The aim of this paper was to design an electrostatic electron focusing lens for the first-generation prototype compact X-ray tube primarily consisting of a carbon nanotube-based electron source and a transmission-type anode by studying the multiple variables that affect the focal spot size (FSS) and by comparing different types of electrostatic lenses with the help of simulations. This multivariable simulation study was conducted using an object-oriented particle-in-cell code, OOPIC PRO. The results of these simulations showed the following: Einzel lens can achieve the required FSS (lower than 1 mm); lens aperture, thickness, and location of the lens can be used as a coarse control over the FSS, whereas the lens potential can be used as a fine control; and the chromatic and spherical aberrations can be reduced if Einzel lens is used. [ABSTRACT FROM AUTHOR]

The emission of X-ray quanta, neutrons, and charged particles from deuterated structures under X-ray irradiation is studied. Targets (deuterated chemical-vapor-deposited (CVD)-diamond, palladium, zirconium, and titanium) are irradiated with the use of an X-ray tube equipped with a polycapillary lens with an energy of up to 30 keV and an X-ray tube equipped with a collimator with an energy of up to 25 keV. Different types of detectors, such as a multichannel neutron detector based on He-3 counters, a CR-39 plastic track detector, and silicon surface barrier detectors, are used. The emission of neutrons with an energy of above 10 MeV and alpha particles with an energy range of 7–15 MeV is revealed. This result indicates the possibility of stimulating multiparticle fusion reactions between deuterium nuclei in solid deuterated structures. The analysis of X-ray fluorescence spectra demonstrate the existence of "additional" peaks, which cannot be identified by any characteristic X-ray fluorescence line. Their appearance cannot be associated with any known element or diffraction process. The nature of the origination of the "additional" peaks requires special study. [ABSTRACT FROM AUTHOR]