Absorption Of X-ray Radiation Research Articles

Neem leaves mediated synthesis of CeO2 nanoparticles for X/gamma ray absorption applications.

Cerium oxide (CeO2) nanoparticles (NPs) exhibit a variety of properties, which have prompted researchers to explore CeO2 NPs in various applications such as biomedical, electrochemical, gas sensing and display applications. CeO2 NPs capabilities were impacted by the type of synthesis mechanism. CeO2 NPs were synthesized by solution combustion method using neem leaves extract as a reducing agent. The synthesized sample is characterized with different techniques. The Bragg reflections confirm the formation of cubic spinel structure. The surface morphology consists of agglomerated NPs. The direct energy band gap was found to be 2.9eV. X-ray radiation absorption properties were studied within 1keV-100GeV range. The results indicate that CeO2 NPs found to be potential in radiation applications.

Investigation of silver nanoparticles embedded in extracted gelatins from camel, bovine, and fish bones for possible use in radiation dosimetry

Abstract Gelatins from camel, bovine, and fish bones were successfully extracted by using chemical pretreatment and heating methods. The bones were demineralized for 3 days at ambient temperature using hydrochloric acid solutions (0.5–1 M), and the collagen was partially hydrolyzed by preheating in distilled water at 75–80°C for 3 h, followed by extraction temperature at 90°C for 1 h. Free-standing films of gelatin entrained with silver nanoparticles (Gel/AgNPs) at low concentrations (1.25, 2.5, and 5 mM) were synthesized as radiation dosimeters. A high-energy ultrasonic homogenizer was used to dissolve the gelatin in distilled water and to disperse the AgNPs in the gelatin. The nanocomposites’ morphology and crystallinity were investigated using scanning electron microscopy (SEM), optical absorption, and Fourier transform infrared (FTIR) spectroscopies. Dose enhancement was assessed using X-ray irradiations with beam energies below and above silver K-edge. The beam was configured by setting the X-ray generator at 15, 25.5, and 35 kV potential and a beam current of 1 mA. An X-ray detector is used to detect the number of electrons after passing through Gel/AgNPs samples. The use of AgNPs embedded in gelatin caused the enhancement of X-ray radiation absorption, and the highest percentage of linearity for the dosimeter was found to be 90% in the optical range of 395 nm to 425 nm. The preliminary results demonstrated that Gel/AgNPs material may be used in radiation dosimetry for low-energy radiotherapy sources.

About the assessment of sampling error and representative sample in X-ray fluorescence analysis of mineral powders

The assessment of laboratory sampling errors in X-ray fluorescence analysis (XRF) of mineral powders ground to a particle size less than 75 μm is important when analyzing specimen portions less than 100–300 mg. The sampling error can be found from Poisson statistics, which allows one to estimate the variations in the number of mineral grains containing an analyte in a powder sample of a fixed mass. However, the absorption of X-ray radiation in the sample imposes a limitation on the analyzed mass due to the low penetration depth of X-rays, especially in the energy region below 4 keV.In this paper, we propose the sampling error estimation based on Poisson statistics taking into account the size of powder particles in comparison with the penetration depth of X-rays. Two limiting cases are considered, when the penetration depth is greater or less than the size of the grains containing the analyte. Zircon, ilmenite, and quartz were considered as grains containing the analyte, and boric acid and clay were taken as matrices. Measurements were carried out with wavelength dispersive XRF spectrometer. It was shown that the sampling errors obtained experimentally for different model mixtures are close to the sampling errors calculated using Poisson statistics. The described model of quartz inclusions in clay matrix was used to explain the relatively low sampling error in determining the main components Al2O3, SiO2, K2O in course-grain Neolithic ceramics.

STUDY OF THE INHOMOGENEOUS ABSORPTION OF X-RAY RADIATION BY A SPHERICAL CRYSTAL SAMPLE

When studying the absorption of X-rays, that the linear absorption coefficient is usually assumed constant throughout the entire volume of the sample under study. However, it can vary in different parts of the crystal, e.g., due to defects present or inhomogeneous inclusion of impurity and doping elements. The results of studying the features of X-ray absorption by a spherical crystalline sample under an assumption that the absorption coefficient is described by a certain function of coordinates are presented. Methods for correcting the diffraction data for such crystals, as well as numerical calculations of the absorption corrections for reflection intensities are proposed. It is shown that the inhomogeneity of absorption in a spherical sample can have a significant effect on the intensity of reflections recorded during a diffraction experiment in the framework of X-ray diffraction analysis (XKD). It is revealed that the attenuation coefficient of a diffracted beam depends on the direction of the absorption coefficient gradient. The results obtained can be used in precision X-ray diffraction analysis of the crystals of some solid solutions. The results of modeling the absorption of X-ray radiation by the samples with different laws of change in the absorption coefficient can be used to identify samples with an inhomogeneous composition.

Nanoluminofors based on siliсates and germanates of rare earth elements for visualization of biotissues

Nanoparticles of silicates and germanates with a general formula Sr2R8–x–yErxYbyM6O26 (R = Y, La; M = Si, Ge) were produced in vacuum by the method of pulse electron beam evaporation. An upconversion photoluminescence of the nanoparticles was detected during the excitation by a laser with a wavelength of 980 nm with a predominance of lines in the red and near infrared regions of the spectrum. Due to their optical properties, the nanoparticles can be excited directly through the biotissues to visualize various pathologies. The obtained nanosamples have K-jumps of X-ray radiation absorption in the 10−100 keV energy region. This opens up prospects for the use of the nanoparticles as X-ray contrast agents. Thus, the nanoparticles have both optical and X-ray contrast characteristics, and therefore have the potential necessary for imaging and diagnosing pathologies in biological tissues.

Synthesis and characterization of resin lead acetate composites and ability test of X-ray protection

Radiation is widely used in various fields, especially in the health sector, but radiation can cause dangers. Including genetic mutations, therefore we need a system to protect from these dangers. One of the radiation protection systems is to use lead glass. In this research, an alternative substitute for lead glass is offered where a composite resin has been made with the addition of lead acetate variations. Several tests have been carried out including the absorption of x-ray radiation reaching 100% obtained at a sample thickness of 13mm with a ratio of 50% resin and 50% lead acetate. In SEM testing, it was obtained dense morphological results and EDX testing showed a balance of constituent compounds between Carbon (C), Oxygen (O) and Lead (Pb) in this sample.

Assessing the fidelity of neural network-based segmentation of soil XCT images based on pore-scale modelling of saturated flow properties

Direct imaging methods, among which X-ray computed tomography (XCT) continues to dominate, enable the study of soil structure at different scales. However, to compute different morphological parameters or assess soil physical properties using pore-scale modelling we need to perform image segmentation to divide the XCT greyscale image representing local absorption of X-ray radiation into major constituents or phases. Here we focused on the simplest type of segmentation procedure – binarization into pores and solid phases. We present the initial results for soil XCT image segmentation using convolutional neural networks (CNN). We assumed that current state-of-the-art local segmentation approaches could provide ground truth data to perform neural network training. We used hybrid U-net + ResNet-101 architecture and segmented seven soil XCT images. The training was performed by excluding the segmented image from training and validation datasets. The segmentations’ accuracy was assessed using standard computer vision metrics (precision, recall, intersection over union or IoU) and pore-scale simulations to compute the permeability of resulting 3D binary soil images. Depending on the soil sample, the error of segmentations in terms of computed hydraulic properties varied from 5% to 130%. The IoU metric was found to be the most sensitive to false positive and false negative porosity predictions by the neural network. To explain observed variations, we performed ground-truth and original XCT greyscale images analysis with the help of correlation and covariance functions. In addition to a comparison between images, we also trained another segmentation neural network that used all samples as a training/verification dataset that helped to explain the inaccuracies caused by insufficient representativeness of some soil sample structures in the training dataset. We discussed possible ways to improve the segmentation results in the future, including the usage of larger soil image libraries, physically modelled ground-truth data, and advanced neural network architectures.

Fabrication and analysis of radiation dose for elastic lead polyester composites as a glass coating

Radiation affecting the human body can cause harm to workers from the lightest to the most fatal. As a result of these interactions, cells can undergo structural changes. Therefore a radiation shield is needed for radiation protection purposes. In this research, a polyester composite sample was made with a variation of lead doping concentration and illumination strength test using a flux meter to determine the permeability of the sample to light, as well as an X-ray radiation absorption test of the sample as desired by the lead polyester being able to be an alternative from the constituent materials of lead glass as a radiation shield that has the advantage of a high level of elasticity so as to minimize the risk of damage (break). Obtained the best mixture composition of 30% Lead Acetate and 70% Lead Polyester, with a radiation exposure test of 35 µSv the results of the radiation absorbing dose on the thickness of the 15mm lead resin layer and Transparency test with an inhibitory value of light of 394 Lux from an initial light source of 700 lux and the rest of the light that is able to penetrate a sample of 306 Lux

3D distribúcia minerálnych inklúzií v granátoch z lokalít Lesné - Potičky a Beňatinská voda (Slovenská republika)

Visualization of garnets and their mineral inclusions was performed by X-ray microtomography by reconstructing 3D image from 1800 measured 2D X-ray projections. Visualization procedure of 3D distribution of mineral inclusions was based on the different absorption of X-ray radiation between the host garnet and mineral inclusions. 3D visualization provided a realistic picture of a distribution of the 126 identified mineral inclusions in garnet from rhyolite and rhyodacite Beňatinská voda and 21 inclusions in garnet from Lesné - Potičky (Slovak Republic). Composition of garnet from locality Lesné - Potičky is Alm71.0-73.7Prp8.3-9.0Grs14.7-16.6 and from locality Beňatinská voda is Alm72.1-73.2 Prp5.5-5.9Grs18.3-19.4. Mineral inclusions in garnets from locality Lesné - Potičky are represented by fluorapatite, zircon, ilmenite, annite and magmatic melts preserved in the form of glass inclusions trapped in apatite inclusions. Mineral inclusions in garnets from locality Beňatinská voda are represented by fluorapatite, zircon and plagioclase An78.53-57.12. Chemical composition of zircons and fluorapatites are similar from both localities. Based on the chemical composition, the high-pressure origin of garnets associated with I-type magmas was confirmed.

High-Performance X-ray Detection Based on One-Dimensional Inorganic Halide Perovskite CsPbI3.

Recently, three-dimensional (3D) halide perovskites were considered as X-ray detection materials because of their high mobility, carrier lifetime, and absorption of X-ray radiation. However, their detection sensitivity and instability at extreme conditions and environments still require optimization. In our present research work, we report using one-dimensional (1D) inorganic halide perovskite CsPbI3 crystals for stable X-ray detection. Remarkably, an X-ray detector made of CsPbI3 has a high sensitivity of 2.37 mC·Gy-1·cm-2, which is an order of magnitude greater than that of detectors using 3D halide perovskites reported previously. The high-sensitivity X-ray detection of CsPbI3 crystals is attributed to their high resistivity of 7.4 × 109 Ω·cm and large carrier mobility-lifetime product of 3.63 × 10-3 cm2·V-1. Our investigation demonstrates the quite promising applications of X-ray detectors made of the low-dimensional perovskite crystals.

Fabrication of micro-scale radiation shielding structures using tungsten nanoink through electrohydrodynamic inkjet printing

Electronics components used in space and strategic missions are exposed to harsh radiation environments, which could cause operational malfunction of the system through lattice displacement or ionization effects. One potential solution is to use tungsten as radiation shielding. Tungsten is a very effective material in shielding electronic components and manufacturing gratings for x-ray imaging. However, intrinsic properties of tungsten (e.g. density, chemical/thermal inertness and hardness) post a significant challenge of fabricating the material into micro-scale and delicate structures, especially in electronic device fabrication. To address the problem, we designed a new tungsten nanoink and developed a straightforward approach to create tungsten micro-structures by 3D printing. Various microstructures down to 10 µm resolution have been patterned and fabricated by electrohydrodynamic inkjet (e-jet) printing using tungsten nanoink. By optimizing process parameters (voltage modality) and materials properties (ink formulation), the dimension and morphology of the structures can be precisely controlled. An AC-modulated voltage was employed during the e-jet printing process to make the patterns much more controllable and stable. Multi-layer tungsten lines were characterized by x-ray imaging and exhibited excellent absorption of x-ray radiation. With the same thickness, printed lines showed nearly 1/3 absorptivity of x-ray radiation of bulk tungsten, leading to significant radiation attenuation effectiveness. Tungsten nanoink is a new material used in e-jet printing that has not been reported in the literature to the best of authors’ knowledge. The study establishes a new methodology of manufacturing micro-nano scale shielding components for electronic devices and rapid prototyping of gratings and collimators in radiography for medical and inspection applications. The research also provides practical guidance to fabricate high melting-point metals via nanoink and micro/nano scale 3D printing.

Synthesis and characterization of silicone rubber composite silica as the x-ray shielding

Radiodiagnostics are diagnostics utilizing X-rays or radiochemical tracers. At the time of exposure using radiation, there may be radiation exposure that will affect the radiation workers. The purpose of this research is to develop materials that can be used as radiation shielding while maintaining radiodiagnostic examination results. This material is made by combining silicone rubber (SR) and silica composites materials through a simple process with a sample size (12 x 12 x 0.5 cm3). Samples were made in 2 variations using silicone rubber and silicone rubber-6% silica composite. Both samples were then tested using a mobile X-ray plane with tube voltage variations of 46 kV, 50 kV, 60 kV, 70kV, 81kV, 90kV, and 102kV, respectively. After being tested, the results of the X-ray transmission percentage for SR sheet at the minimum and maximum voltage are 60% and 75%, respectively. For SR-6% Silica sheet X-ray transmission percentage at the minimum and maximum stresses of 58% and 74%, respectively. This research results showed that the use of silica on SR has potential as a composite material that can provide increased absorption of X-ray radiation.

The eye of the endourologist: what are the risks? A review of the literature.

During endourological procedures, the eye of the urologist is exposed to hazards such as contact with body fluids and irrigation solutions as well as laser injury, and X-ray radiation absorption. The resulting potential injuries and damages to the eye have not been summarily reviewed to date. The objective was to review the different risks of exposure to the eyes of urologists during endourological procedures. The Medline database was searched for identification of studies on hazards to the eye of the endourologist. All articles published in English until September 2018 were considered. Twenty-three publications were included in this analysis. The incidence of eye contact with patient body fluids or irrigation solutions during endoscopic procedures ranged between 37.50 and 100%. Laser-induced eye injuries were reported in 37.9% of all kind of adverse events related to laser use in urology. The eye lens dose of radiation ranged from 0.04 to 1600µSv per endourological procedures. While the risks of infection, laser injury, lens opacity and cataract are generally low, the wear of protective glasses is recommended. Lead glasses may protect against all these risks in case of Ho:YAG laser use with concomitant X-ray radiation. If Ho:YAG laser is used without any concomitant X-ray radiation, proper laser safety glasses or at least conventional eyeglasses should be recommended. When other types of laser are used, we recommend wearing laser eye protection glasses covering the adequate range of wavelength. For endourological procedures without laser use and X-ray radiation, specific protection devices such as goggles or face shields are recommended.

Stacked competitive networks for noise reduction in low-dose CT.

Since absorption of X-ray radiation has the possibility of inducing cancerous, genetic and other diseases to patients, researches usually attempt to reduce the radiation dose. However, reduction of the radiation dose associated with CT scans will unavoidably increase the severity of noise and artifacts, which can seriously affect diagnostic confidence. Due to the outstanding performance of deep neural networks in image processing, in this paper, we proposed a Stacked Competitive Network (SCN) approach to noise reduction, which stacks several successive Competitive Blocks (CB). The carefully handcrafted design of the competitive blocks was inspired by the idea of multi-scale processing and improvement the network’s capacity. Qualitative and quantitative evaluations demonstrate the competitive performance of the proposed method in noise suppression, structural preservation, and lesion detection.

Hydrodynamic modelling of accretion impacts in classical T Tauri stars: radiative heating of the pre-shock plasma

Context. It is generally accepted that, in Classical T Tauri Stars, the plasma from the circumstellar disc accretes onto the stellar surface with free fall velocity, and the impact generates a shock. The impact region is expected to contribute to emission in different spectral bands; many studies have confirmed that the X-rays arise from the post-shock plasma but, otherwise, there are no studies in the literature investigating the origin of the observed UV emission which is apparently correlated to accretion. Aims. We investigated the effect of radiative heating of the infalling material by the post-shock plasma at the base of the accretion stream with the aim to identify in which region a significant part of the UV emission originates. Methods. We developed a 1D hydrodynamic model describing the impact of an accretion stream onto the stellar surface; the model takes into account the gravity, the radiative cooling of an optically thin plasma, the thermal conduction, and the heating due to absorption of X-ray radiation. The latter term represents the heating of the infalling plasma due to the absorption of X-rays emitted from the post-shock region. Results. We found that the radiative heating of the pre-shock plasma plays a non-negligible role in the accretion phenomenon. In particular, the dense and cold plasma of the pre-shock accretion column is gradually heated up to few $10^5$\;K due to irradiation of X-rays arising from the shocked plasma at the impact region. This heating mechanism does not affect significantly the dynamics of the post-shock plasma. On the other hand, a region of radiatively heated gas (that we consider a precursor) forms in the unshocked accretion column and contributes significantly to UV emission. Our model naturally reproduces the luminosity of UV emission lines correlated to accretion and shows that most of the UV emission originates from the precursor.

Picosecond resolving detection method and experiment for ultrafast X-ray by modulation of an optical probe

Diagnostic measurement of single picosecond event in high energy density physics, laser fusion, plasma radiation, and combustion, is of great importance. However, the measuring of the shape of the single X-ray pulse and the synchronization of X-ray and the laser pulse in picosecond resolution is still a great challenge. Restricted by the transit time of electrons, the time-resolution limit of a conventional framing camera based on the microchannel plate is 40 ps. Centered on the full-optical modulation effect of the light-probe, a novel method for X-ray detection of picoseconds temporal resolution based on low temperature GaAs is proposed in this work. The basic physical mechanism of the detector can be explained in both macroscopical and microcosmic ways. In the macroscopical way, the X-ray radiation absorption in the sensor material produces a transient, non-equilibrium electron-hole pair distribution that results in a transient differential change of the local refractive index, which is then sensed by the reflectivity changes of the optical probe beam. In the microcosmic way, X-ray absorption creates photoelectrons and the core level holes are subsequently filled through Auger or fluorescence processes. These excitations ultimately increase conduction and valence band carriers that perturb optical reflectivity.#br#To verify the proposed X-ray detection method, a Fabry-Perot detector is designed, which consists of a 5 μm thick GaAs layer surrounded by a GaAs/AlAs distributed Bragg reflector. The test is carried out on a femtosecond laser facility, where the X-ray source is produced by focusing the 56 fs Ti: Sapphire facility laser, with a central wavelength of 800 nm, onto an aluminum foil. Then the X-ray pulse induces a transient optical reflectivity change in GaAs, which is a powerful tool for establishing the high-speed X-ray detection.#br#The experimental results indicate that this technology can be used to provide X-ray detectors with a temporal resolution of tens of picoseconds. By optimizing the material, the temporal resolution can be enhanced to be less than 1 ps. Through further development, this X-ray detector could provide an insight into previously unmeasurable phenomena in many fields. Future work will focus on developing much faster devices characterizing both the rise and fall time and imaging array technology.

In-Depth Distribution of Stresses Measured by Multireflection Grazing Incidence Diffraction

The geometry based on the multireflection grazing incidence X-ray diffraction (called the MGIXD method) can be applied to measure residual stresses. Using this method, it is possible to perform a non-destructive analysis of the heterogeneous stresses for different and well defined volumes below the surface of the sample (range of several mm). As the result the average values of stresses weighted by absorption of X-ray radiation are measured. In this work the stress profile as a function of depth for mechanically polished Ti and Al samples were calculated from MGIXD data using inverse Laplace transform.

Advances in small-angle X-ray scattering for the study of supported catalysts

Ru particle sizes in supported ruthenium catalysts have been studied by small-angle X-ray scattering (SAXS). It has been proposed to use new masking liquids with a relatively low X-ray radiation absorption. Using these liquids it was possible to achieve practically quantitative agreement between SAXS and transmission electron microscopy data. The SAXS technique employing such masking liquids can be used as a quick analytical method for determining the particle size distributions of supported metals. Fluorocarbon liquids can eliminate the scattering signal from any support with a density of 2.5 g cm−3or less. This procedure can be very useful for selective study of separate components in complex samples consisting of carbon materials, silica materials, polymers, some hydroxides, claysetc.

Soft X-ray interaction with organic molecules of biological interest: the pyrimidine and halogenated pyrimidines cases

Molecular fragmentation following absorption of X-ray radiation is one of the effects of radiation damage. To investigate this process in a class of organic molecules of biological interest the inner shell excitation, ionisation, electron decay and fragmentation of the pyrimidine molecule have been fully characterised by electron and ion spectroscopies and theoretical calculations. These techniques enabled us to observe site-selective molecular fragmentation of the N and C (1s) core excited states and to explain that it is governed by the final singly charged ion state populated by resonant Auger electron decay.

Multireflection grazing incidence diffraction used for stress measurements in surface layers

The geometry based on the multireflection grazing incidence X-ray diffraction can be applied to measure residual stresses. Using this method, it is possible to perform a non-destructive analysis of the heterogeneous stresses for different and well defined volumes below the surface of the sample (range of several μm). As the result, the average values of stresses weighted by absorption of X-ray radiation are measured. In this work the stress profiles as a function of penetration depth were determined for mechanically polished Al sample. Measurements and verification of the method were performed using classical X-ray diffractometer and synchrotron radiation with different wavelengths.