Low-energy X-ray Research Articles

Characterization and calibration of DECTRIS PILATUS3 X CdTe 2M high-Z hybrid pixel detector for high-precision powder diffraction measurements

Silicon-based hybrid photon-counting pixel detectors have become the standard for diffraction experiments of all types at low and moderate X-ray energies. More recently, hybrid pixel detectors with high-Z materials have become available, opening up the benefits of this technology for high-energy diffraction experiments. However, detection layers made of high-Z materials are less perfect than those made of silicon, so care must be taken to correct the data in order to remove systematic errors in detector response introduced by inhomogeneities in the detection layer, in addition to the variation of the response of the electronics. In this paper we discuss the steps necessary to obtain the best-quality powder diffraction data from these detectors, and demonstrate that these data are significantly superior to those acquired with other high-energy detector technologies.

Eye lens dosimetry: does the direction of rotation (vertical or horizontal) play a role in type testing?

With the International Commission on Radiological Protection (ICRP) lowering the annual dose limit for the eye lens to 20 mSv, precise monitoring of eye lens exposure has become essential. The personal dose equivalent at a depth of 3 mm, Hp(3), is the measurement method for monitoring the dose to the lens of the eye. Traditional dosimetry methods primarily address lateral radiation exposure scenarios, where radiation approaches from the left or right, necessitating the rotation of the phantom during type testing around the vertical axis. However, these methods do not adequately account for bottom-to-top radiation exposures which are common in real-world situations (such as radiation scattered by the patient reaching medical staff).
This study examines oblique radiation exposure conditions using a typical eye lens thermoluminescent dosemeter (TLD), Eye-D, placed on a cylindrical phantom to assess dose responses at different angles and exposure energies. The study employs both lower-energy (N-30 radiation quality) and higher-energy (N-100 radiation quality) X-rays at irradiation angles of -60°, 0°, and +60°, measured along the vertical and horizontal rotation axes of the phantom.
The results show no significant differences between horizontal and vertical (polar and radial) rotation orientations of the dosemeter-phantom setup: recorded relative doses stayed well within ±1%, i.e., by far within the attributed combined uncertainty of ±2%.&#xD.

Alternative X-ray attenuation material from iodide-starch-gel-based materials

Background: Iodine is often used as a contrast media because the k-shell binding energy (K-edge) is 33.2 keV, the average energy of a diagnostic X-ray. Thus, iodine can be utilized as a radiation attenuation material for X-rays. Objective: This study aimed to produce low-energy X-ray attenuation materials used as X-ray shielding. A sodium iodide compound will be synthesized by polymerizing mung bean starch with sodium iodide. Materials and methods: The iodide-starch-gel-based material (ISG) was made by mixing a mung bean starch solution (10 %w/w) with a sodium iodide (NaI) solution (100, 200, 250, and 300 mg-Iodine/gm). The linear attenuation coefficient (µ) was determined using radiation dose acquired from the DR plate system and CdTe detector. The X-rays were done at 50 - 120 kVp to study the attenuation properties. Results: The results showed that the linear attenuation coefficient of t ISG was slightly higher than that of sodium iodide solution at the same concentration. The spectrum still shows an X-ray absorption characteristic at about 30.1-40.5 keV K-edge range. Conclusion: Iodide-starch-gel-based components can attenuate X-ray with a K-edge range from 30-40 kVp. The attenuation coefficient of X-ray radiation varies linearly with energy level. Moreover, the concentration of the NaI solution is directly proportional to the attenuation of X-ray radiation. Thus, based on these properties and the gel-like consistency of the substance, it can be developed into a surface coating material to reduce X-ray radiation exposure.

Simulation and experimental study of low-energy fluorescence X-rays

Simulation and experimental study of low-energy fluorescence X-rays

Capillary Force-Assisted CsPbBr3-xIx (x = 0, 1) Columnar Crystal Film for X-ray Detectors with Ultrahigh Electric Field and Sensitivity.

Inorganic halide perovskite thin-film X-ray detectors have attracted great research interest in recent years due to their high sensitivity, low detection limit, and facile fabrication process. The poor crystal quality of the thin film with uncontrollable thickness and low background voltage during detection limits its practical application. Here, a high-quality CsPbBr3-xIx (x = 0, 1) columnar crystal film is prepared by an improved melt-confined method with a porous anodic aluminum oxide (AAO) template, which stabilizes the disorder perovskite systems of CsPbBr2I by stress. The AAO-CsPbBr3-xIx (x = 0) detectors exhibit high detection accuracy and photoelectric conversion capability with an ultrahigh sensitivity of 32,399.5 μC·Gyair-1·cm-2 at 2142.9 V mm-1 under 20 kVp X-rays and 19,217.4 μC·Gyair-1·cm-2 with a higher background electric field of 6666.7 V mm-1 for AAO-CsPbBr3-xIx (x = 1). Moreover, the AAO-CsPbBr3-xIx (x = 1) film detector acquires a lower detection limit of 7.65 nGy·s-1 and a higher X-ray imaging spatial resolution of 1.6 LP/mm and 8.6 nGy·s-1 and 1.4 LP/mm for AAO-CsPbBr3-xIx (x = 0). The facile, high-quality columnar crystal film devices display great potential for low-energy and low-dose X-ray imaging in flat panel detection applications.

Low-Energy X-Ray Polarization Detector Detection Unit Prototype

Low-Energy X-Ray Polarization Detector Detection Unit Prototype

Response of CaSO4:Dy Teflon embedded thermoluminescent dosimeter badge on different ISO phantoms for photons and beta sources using FLUKA and GEANT4

In this study, Monte Carlo codes FLUKA and GEANT4 were used to assess the angular variation in the response of CaSO4:Dy Teflon disc based TLD badge. These badges were positioned on various ISO phantoms to simulate the angular exposures ranging from 0° to 60° for photons within the energy range of 12.3 keV to 1.25 MeV, as well as for 90Sr/90Y and 106Rh/106Ru beta sources. Plots showing the TL response of the discs in terms of Hp(10), Hp(3), and Hp(0.07) as a function of photon energy were obtained for ISO slab, cylindrical, and pillar phantoms, respectively. Additionally, the study estimated the angular variation in the response of disc ratios (R12 and R32) with respect to both photon and beta energies. The simulation results revealed that the response of the open disc (D3) was higher for lower X-ray energies, attributed to an increase in the photoelectric effect. Conversely, the response of the disc under the metal filter (D1) was observed to increase with the angle, indicating the Compton scattering from the cassette body and phantom, especially at lower X-ray energies. Beta response of both disc D2 (under PMMA filter) and D3 found to be decreasing with the angle of incidence while R32 ratio found to be increasing with the angle of incidence for both 90Sr/90Y and 106Rh/106Ru beta sources. Notably, the simulated results demonstrated good agreement with experimental observations, reinforcing the reliability of the Monte Carlo simulations for complex interactions and responses of TLD badges under different irradiation conditions.

Distribution of the dose response in a silicone-based radio-fluorogenic dosimeter and FWT-60 irradiated with monochromatic low-energy X-rays

In a previous work, we studied the electron spin resonance imaging of the alanine dosimeter irradiated with 0.36–1.8 kGy of 4- and 7-keV monochromatic X-rays and visualized the distribution of alanine radicals as a function of the penetration depth of the X-rays. Herein, the dose-response profile, as a function of the penetration depth, of a silicone-based gel dosimeter and FWT-60 film dosimeter was studied for comparison with the alanine dosimeter. A silicone-based gel dosimeter using dihydrorhodamine 6G (DHR6G) as a fluorescence probe was irradiated with 0–45 Gy of 10-keV monochromatic X-rays. The dose-response profile of the fluorescence was then investigated in detail to demonstrate the properties of low-energy X-ray irradiation. The fluorescence intensity at the surface was less than that inside when irradiated with a higher dose. The total fluorescence intensity per unit dose decreased with the increasing dose. These results were almost the same as those for the alanine dosimeter. At the surface, many of the radicals produced in the silicone elastomer would be lost due to radical-radical recombination before reacting with DHR6G owing to the high linear energy transfer nature of the low-energy X-ray irradiation. The FWT-60 film dosimeter was irradiated with 0.8–10 kGy of 2- and 4-keV monochromatic X-rays. For the FWT-60 film, the dose-response linearly increased with the dose, although its efficiency was far lower than that of the gel dosimeter. Additionally, the slope of the dose-response decreased with the decreasing photon energy. Some of the precursor molecules for the pigment will be directly ionized, transforming into the coloring agent in the FWT-60 film. Finally, the reaction mechanism to produce the pigment in each dosimeter would affect the dose-response properties of irradiation via low-energy X-rays.

Comparison of X-Ray Absorption in Mandibular Tissues and Tissue-Equivalent Polymeric Materials Using PHITS Monte Carlo Simulations

This study investigates the absorption of X-rays in mandibular tissues by comparing real tissues with tissue-equivalent materials using the PHITS Monte Carlo simulation program. The simulation was conducted over a range of X-ray photon energies from 50 to 100 keV, with increments of 5 keV, to evaluate the dose absorbed by different tissues. Real tissues, such as the skin, parotid gland, and masseter muscle, were compared with their tissue-equivalent polymeric materials, including PMMA, Parylene N, and Teflon. The results showed that the real tissues generally absorbed more X-rays than their corresponding equivalents, especially at lower energy levels. For instance, at 50 keV, differences in the absorbed doses reached up to 50% for the masseter muscle and its equivalent, while this gap narrowed at higher energies. The study highlights the limitations of current tissue-equivalent materials in accurately simulating real tissue behavior, particularly in low-energy X-ray applications. These discrepancies suggest that utilizing tissue-equivalent materials may lead to less accurate medical imaging and radiotherapy dose calculations. Future research should focus on improving tissue-equivalent materials and validating simulation results with experimental data to ensure more reliable dosimetric outcomes. This study provides a foundation for refining radiation dose calculations and improving patient safety in clinical applications involving X-rays.

Surface structure of Sn doped β-Ga2O3(010) p(1×1) studied by quantitative low energy electron diffraction

We have studied the surface structure of a single crystal β-Ga2O3(010) using quantitative Low Energy Electron Diffraction (LEED) and X-ray photoelectron spectroscopy (XPS). The XPS measurements show spectra typical of stoichiometric Ga2O3 with a clean surface. LEED consistently shows a p(1×1) pattern, free of surface reconstruction. Quantitative LEED I(V) curves are acquired for 41 distinct diffraction spots. The experimental I(V) curves are compared to simulations over the first five layers. The best fits to the experimental LEED I(V) curves acquired at all diffraction spots are then used to calculate the interplanar relaxation and atomic rumpling. Significant atomic rumpling and interplanar relaxation are found over the first 5 atomic layers. As a result of rumpling a polarization of ∼ 2 µC/cm2 develops in the topmost surface layer. The structural results are in good agreement with previous density functional theory calculations and experimental X-ray photoelectron diffraction.

Feasibility of PET-enabled dual-energy CT imaging: First physical phantom and initial patient study results.

Dual-energy (DE) CT enables material decomposition by using two different x-ray energies and may be combined with PET for improved multimodality imaging. However, this increases radiation dose and may require a hardware upgrade due to the added second x-ray CT scan. The recently proposed PET-enabled DECT method allows dual-energy imaging using a conventional PET/CT scanner without the need to change scanner hardware or increase radiation exposure. Here we demonstrate the first-time physical phantom and patient data evaluation of this method. The PET-enabled DECT method reconstructs a gamma-ray CT (gCT) image at 511keV from the time-of-flight PET data with the maximum-likelihood attenuation and activity (MLAA) approach and then combines this image with the low-energy x-ray CT images to form a dual-energy image pair for material decomposition. To improve the image quality of gCT, a kernel MLAA method was developed using the x-ray CT as a priori information. Here we developed a general open-source implementation for gCT reconstruction and used this implementation for the first real data validation using both physical phantom study and human-subject study. Results from PET-enabled DECT were compared using x-ray DECT as the reference. Further, we applied the PET-enabled DECT method in another patient study to evaluate bone lesions. Compared to the standard MLAA, results from the kernel MLAA showed significantly improved image quality. PET-enabled DECT with the kernel MLAA was able to generate fractional images that were comparable to the x-ray DECT, with high correlation coefficients for both the phantom study and human subject study (R > 0.99). The application study also indicates that PET-enabled DECT has potential to characterize bone lesions. Results from this study have demonstrated the feasibility of this PET-enabled method for CT imaging and material decomposition. PET-enabled DECT shows promise to provide comparable results to x-ray DECT.

Assessing the shielding capability of NiO-infused BPSCCO ceramics against low-energy X-rays

This research examines the improvement of radiation shielding capabilities in Bismuth Strontium Calcium Copper Oxide (BSCCO) superconductors via NiO doping. With the increasing need for advanced shielding materials in high-risk areas, exploring effective and nonhazardous alternatives is becoming increasingly important. The purpose of the study was to investigate the radiation-shielding characteristics of BPSCCO superconducting ceramics and the effects of NiO additives on their shielding properties. Comparisons of linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), as well as fully simulated values for transmission factor (TF), neutron removal cross section (ΣR), electrical conductivity (Ceff), alpha and proton stopping powers, and radiation protection efficiency (RPE) using NIST XCOM, Phy-X, NIST Pstar and NIST Astar for all ceramic samples. The results indicate that optimal NiO doping notably enhances the radiation shielding capabilities of BSCCO ceramics, highlighting their significant potential for use in the medical, aerospace, and nuclear industries. This research provides a fundamental understanding of the potential of doped superconductor ceramics for radiation protection, promoting further research into these materials and the creation of safer, more efficient shielding solutions.

Immunomodulatory hydrogel patches loaded with curcumin and tannic acid assembled nanoparticles for radiation dermatitis repair and radioprotection

Radiation dermatitis, as a major side effect of radiotherapy, is a form of skin injury linked to the production of reactive oxygen species (ROS). Development of functional patches with excellent ROS scavenging ability and biosafety is crucial for radioactive dermatitis repair. Herein, we present a nanohybrid hydrogel patch composed with natural-derived substances. The patch possesses dual functionalities of chemically scavenging ROS and physically absorbing radiation, thereby alleviating radiation damage. Curcumin@tannic acid (Cur@TA) nanoparticles are synthesized through spontaneous coordination of TA and iron ions (Fe3+), enabling the encapsulation of Cur. The nanoparticles are then loaded into gelatin methacryloyl (GelMA) hydrogel patches, which endow the hydrogel with tissue adhesion as well as photothermal properties. Simultaneously, the patch exhibits powerful ROS scavenging capability and promotes M2 polarization of macrophages. Additionally, the high-water content of the GelMA hydrogel enables physical absorption of low-energy X-rays, providing radiation shielding. Based on these characteristics, we have demonstrated the augmented therapeutic efficacy of the hydrogel patch loaded with Cur@TA nanoparticles in the mouse model of radiation dermatitis. Our findings introduce a novel therapeutic approach for radiation protection and treatment, with potential clinical applications.

Enhancing low-energy X-ray excited afterglow in lanthanide-doped fluoride core@shell nanoparticles for autofluorescence-free imaging

Lanthanide-doped fluoride nanoparticles (NPs) exhibit tunable X-ray excited afterglow (XEA), holding great promise for autofluorescence-free flexible X-ray imaging. However, materials with low atomic numbers, while sensitive to low-energy X-ray photons, suffer from weak X-ray absorption coefficients. This poses a significant challenge in achieving high-performance XEA with minimized radiation risk. In this study, we enhance the low-energy XEA of lanthanide activators by engineering the interfacial defect formation energy (Ef) in CaF2-based heterogeneous core/shell nanoarchitectures. Mechanistic investigations demonstrate that a large lattice misfit between the core and shell reduces the interfacial defect Ef, facilitating the formation of Frenkel defects and significantly increasing XEA intensity after low-energy X-ray irradiation. Specifically, the heterogeneous CaF2:Tb@CaLuF5 core/shell NPs, with a misfit of 3.382 %, exhibit approximately ∼ 8.9 times higher XEA intensity compared to the CaF2:Tb@CaF2 homogeneous core/shell NPs at 10 kV. Furthermore, integrating the CaF2:Tb@CaLuF5 NPs into a flexible scintillation screen enables XEA-based delayed imaging with high spatial resolution, up to approximately 14.2 lp mm−1, and an autofluorescence-free background. These findings advance the development of superior low-energy XEA materials and pave the way for autofluorescence-free three-dimensional X-ray imaging.

High-throughput, low-cost FLASH: irradiation of Drosophila melanogaster with low-energy X-rays using time structures spanning conventional and ultrahigh dose rates.

FLASH radiotherapy is an emerging technique in radiation oncology that may improve clinical outcomes by reducing normal tissue toxicities. The physical radiation characteristics needed to induce the radiobiological benefits of FLASH are still an active area of investigation. To determine the dose rate, range of doses and delivery time structure necessary to trigger the FLASH effect, Drosophila melanogaster were exposed to ultrahigh dose rate (UHDR) or conventional radiotherapy dose rate (CONV) 120-kVp X-rays. A conventional X-ray tube outfitted with a shutter system was used to deliver 17- to 44-Gy doses to third-instar D. melanogaster larvae at both UHDR (210Gy/s) and CONV (0.2-0.4Gy/s) dose rates. The larvae were then tracked through development to adulthood and scored for eclosion and lifespan. Larvae exposed to UHDR eclosed at higher rates and had longer median survival as adults compared to those treated with CONV at the same doses. Eclosion rates at 24Gy were 68% higher for the UHDR group (P<0.05). Median survival from 22Gy was >22days for UHDR and 17days for CONV (P<0.01). Two normal tissue-sparing effects were observed for D. melanogaster irradiated with UHDR 120-kVp X-rays. The effects appeared only at intermediate doses and may be useful in establishing the dose range over which the benefits of FLASH can be obtained. This work also demonstrates the usefulness of a high-throughput fruit fly model and a low-cost X-ray tube system for radiobiological FLASH research.

Modeling and benchmarking XRF analysis using MCNP for applications in accident tolerant fuel and cladding

There is an interest in using nondestructive testing (NDT) methods for the preliminary investigation of accident-tolerant fuel cladding materials, such as chromium (Cr) coated Zircaloy-4 (Zr4). One promising application is X-ray fluorescence (XRF) analysis. Computational methods, such as Monte Carlo N-Particle Transport (MCNP) 6.2, can be used to expand algorithms based on XRF measurements, however, it has been demonstrated that MCNP is more sensitive to modeling imperfections at lower energies (≤ 80 keV). In this work, several MCNP models were developed to evaluate the XRF measurements given by a Niton XL-5 device to minimize deviations at low energies. The final model was benchmarked to an experimental XRF measurement of Cr-coated Zr4 taken by the XL-5. The percent error in the resulting XRF peak intensities was within ± 4.92% for the Kα1 peaks and within ± 16.0% for the Kβ1. The discrepancies in the magnitude of these errors are largely due to the Kβ1 peaks having far fewer counts in the spectra that were compared. Nonetheless, these results demonstrate the potential for MCNP 6.2 to accurately predict low-energy X-ray interactions such as XRF. The deviations observed were similar to those seen in the 0.1–1 MeV range in prior works, despite only being in the ∼ 5–30 keV range themselves.

Investigating radiation shielding parameters for X-ray attenuation at various energies in locally produced ceramic materials used in Saudi Arabia

To assess shielding effectiveness against X-rays, a number of locally collected ceramic samples were obtained from the Kingdom of Saudi Arabia. Based on elemental analysis, all of the ceramic samples have a density in the range of 1.68–1.85 g/cm3, with the highest proportions of O, Si, C, and Al atoms and the lowest amounts of Na, Mg, K, Ca, Ti, and Fe. The 320 kV X-ray source (Gulmay Limited, Byfleet, UK) was used to assess the attenuation properties of the ceramic samples. An Exradin A4 ionization chamber (Standard Imaging, Middleton, USA) connected to a UNIDOS electrometer (PTW, Freiburg, Germany) in the control room was used to detect the attenuation properties. Several X-ray attenuation coefficients are evaluated at different X-ray energies in the range of 40–150 kV in this study. These include the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP). The ability of any ceramic sample under investigation to shield radiation at low X-ray energy is indicated by the theoretical and experimental values of LAC. The potential applications of these easily accessible, reasonably priced ceramic materials for radiation protection in X-ray labs and low-energy X-ray shielding in a variety of fields have been shown by this investigation.

Spatial resolution studies using point spread function extraction in optically read out Micromegas and GEM detectors

Optically read out gaseous detectors are used in track reconstruction and imaging applications requiring high granularity images. Among resolution-determining factors, the amplification stage plays a crucial role and optimizations of detector geometry are pursued to maximize spatial resolution. To compare Micro Pattern Gaseous Detector (MPGD) technologies, focused low-energy X-ray beams at the SOLEIL synchrotron facility were used to record and extract point spread function widths with MICRO-Mesh Gaseous Structure (icromegas) and Gas Electron Multiplier (GEM) detectors. Point spread function width of ≈108µm for Micromegas and ≈127µm for GEM foils were extracted. The scanning of the beam with different intensities, energies and across the detector active region can be used to quantify resolution-limiting factors and improve imaging detectors using MPGD amplification stages.

Enhanced X-ray shielding efficiency and visible light degradation performance of a multilayer composite protective material

To mitigate the adverse effects of high-energy radiation, such as X-rays, on patients during medical procedures, a multifunctional composite nanofibrous membrane has been engineered to shield against low-energy X-rays. This study involves integrating processed oil-tea camellia shells (OCS) powder into molten polylactic acid (PLA) for modification. Concurrently, metallic Bi is introduced to enhance Bi2WO6, which is subsequently combined with modified PLA and electrospun into nanofibrous membranes for photocatalytic antimicrobial and organic pollutant degradation. Additionally, sodium hyaluronate (NaHA) and a silver nanoparticle solution are electrospun with PLA to form a skin-friendly protective layer. Following this, a chitosan (CS) solution containing WO3 and B4C is used as a coating on the multilayered membranes. The membranes are then freeze-dried to create sandwich-structured multilayer composite protective material. This method addresses challenges associated with polylactic acid (PLA) in electrospinning and alleviates limitations such as low light absorption and slow charge transfer in Bi2WO6. Compared to similar materials, this composite material is lightweight, flexible for cutting, and exhibits strong X-ray shielding capabilities. The composite nanofibrous membrane demonstrates a shielding efficiency of 97.75 ± 2.05 % at low X-ray energy (46 kVp). Moreover, under visible light, the membrane generates reactive oxygen species, resulting in the efficient removal of 98.03 % of methylene blue (MB), 96.35 % of rhodamine B (Rh.B), and 91.51 % of methyl orange (MO) within 180 minutes. Furthermore, it displays bactericidal activity against E. coli and S. aureus under both dark and light conditions. In natural settings, the composite membrane undergoes gradual degradation in soil, completely decomposing within 28 days due to the influence of rainfall and microorganisms. Consequently, this composite membrane holds significant promise for specialized medical protective applications.

Polarization Degree of Magnetic Field Structure Changes Caused by Random Magnetic Field in Gamma-Ray Burst

In a Poynting-flux-dominated jet that exhibits an ordered magnetic field, a transition toward turbulence and magnetic disorder follows after magnetic reconnection and energy dissipation during the prompt emission phase. In this process, the configuration of the magnetic field evolves with time, rendering it impossible to entirely categorize the magnetic field as ordered. Therefore, we assumed a crude model that incorporates a random magnetic field and an ordered magnetic field, and takes into account the proportionality of the random magnetic field strength to the ordered magnetic field, in order to compute the polarization degree (PD) curve for an individual pulse. It has been discovered that the random magnetic field has a significant impact on the PD results of the low-energy X-ray. In an ordered magnetic field, the X-ray segment maintains a significant PD compared to those in the hundreds of keV and MeV ranges even after electron injection ceases, making PD easier to detect by polarimetry. However, when the random magnetic field is introduced, the low-energy and high-energy PDs exhibit a similar trend, with the X-ray PD being lower than that of the high-energy segment. Of course, this is related to the rate of disorder in the magnetic field. Additionally, there are two rotations of the polarization angles (PAs) that were not present previously, and the rotation of the PA in the high-energy segment occurs slightly earlier. These results are unrelated to the structure of the ordered magnetic field.