Search Results (679)

This study investigates neutron radiation sources in medical cyclotrons used for PET isotope production, focusing on differences between ¹⁸F and ¹¹C. Neutron and gamma dose rates were measured in the bunker and operator control room during routine production with an 11 MeV Eclipse cyclotron. ¹⁸F production generated approximately 2.5 times higher neutron levels in the bunker than ¹¹C. Shielding performance also varied: the same wall reduced neutron fluxes by factors of k_F = 14,000 for ¹⁸F and k_C = 86,000 for ¹¹C, while gamma shielding was similar for both isotopes (k_γ ≈ 28,000). However, the neutron shielding factor calculated from the data for ¹⁸F should be taken as k_F ≥ 1.4 × 10⁴, because several neutron readings reached the upper limit of the detector range, which indicates a partial underestimation of the dose in the bunker. Consequently, neutron levels in the control room during ¹⁸F production were about 15-fold higher than during ¹¹C production. These differences result from distinct neutron generation mechanisms. The ¹⁸O(p,n)¹⁸F reaction produces primary neutrons with a Maxwellian spectrum (~2.5 MeV), while ¹¹C neutrons arise solely from secondary interactions in structural materials. The findings emphasize the need for composite shielding adapted to isotope-specific spectra. Annual dose estimates (260 ¹⁸F and 52 ¹¹C productions) showed neutron exposure (3.78 mSv/year, 57%) exceeded gamma exposure (2.82 mSv/year, 43%). The total dose of 6.6 mSv/year is ~33% of regulatory limits, supporting compliance but underscoring the need for dedicated neutron dosimetry. Full article

We examined whether synchronizing and analyzing three data sources, active personal dosimeter (APD) information, in-room monitoring camera footage, and the operator’s main angiography panel video, could identify opportunities to reduce occupational radiation exposure during cerebral angiography without therapeutic intervention. We analyzed the behavior of eight physicians and radiation doses measured outside the lead apron during 12 diagnostic cerebral angiography procedures performed between January and April 2024. Appropriate use of a ceiling-suspended radiation protective shield (CSRPS) was associated with approximately 70% exposure reduction. In addition, exposure during femoral arteriography (catheter advancement from femoral artery puncture to the aortic arch) accounted for approximately 50% of the total exposure, identifying both as effective intervention points. This approach identified operators’ incorrect use of radiation protection equipment and enabled clear feedback to operators on areas for improvements in radiation protection practices. Full article

Compact fusion reactors are receiving increasing interest as a promising route for accelerating the path toward commercial fusion, thanks to their reduced size and cost. However, this compactness introduces new technological challenges, including higher radiation loads on critical functional components, such as the magnet system. Neutron shielding is therefore of utmost importance to guarantee the expected lifetime of the device, and its selection must account for the harsh environment imposed by the high radiation flux. Shielding materials should be structurally stable, not melt within the operational temperature windows, and be relatively low-cost. For nuclear reactor applications, binary compounds are typically the preferred choice as they often meet these requirements, particularly in terms of availability and cost. In this work, we present a systematic Monte Carlo analysis of more than 700 binary compounds, exposed to the neutron spectrum at the most loaded position of the vacuum vessel in a simplified model of a compact fusion reactor. Shielding performances were evaluated in a toroidal geometry in terms of neutron attenuation, power deposition, and activation, leading to the identification of several promising compositions for effective neutron shielding in future fusion applications. Full article

High-energy microfocus X-ray sources are increasingly applied in non-destructive testing, high-resolution imaging, and additive manufacturing. The design and optimization of the anode target critically determine source efficiency, spectral characteristics, and imaging performance. In this study, Monte Carlo simulations using the Geant4 toolkit were conducted to systematically evaluate transmission and reflection tungsten targets with varied thicknesses and incidence angles under electron beam energies ranging from 100 to 300 keV. The results reveal that, for a microfocus X-ray source operating at a maximum tube voltage of 225 kV, the optimal transmission tungsten target exhibits a thickness of 18 μm, whereas the optimal reflection tungsten target achieves maximum efficiency at a 30 μm thickness with a 25° incidence angle. A nearly linear relationship between electron energy and optimal transmission target thickness is established within the 100–300 keV range. Additionally, the influence of beryllium window thickness and filter materials on the emergent X-ray spectrum is analyzed, demonstrating pathways for spectral hardening and transmission optimization. This study further elucidates the angular–intensity distribution of emitted X-rays, providing critical insights into beam spatial characteristics. Collectively, these findings establish a theoretical foundation for target optimization, enabling enhanced X-ray source performance in high-resolution imaging and supporting applications in detector calibration, flatness correction, beam hardening correction, and radiation shielding design. Full article

An investigation was carried out to improve the gamma radiation shielding properties of Benecel K4M pharmaceutical polymer using zinc oxide (ZnO) at concentrations from 0 to 6 wt.%. Compressed composite tablet samples were prepared and tested in the range of photon energies 59.5 to 1332 keV for the assessment of various shielding parameters, including linear attenuation coefficient, radiation protection efficiency (RPE), and mean free path (MFP). As the ZnO content increased, the attenuation properties of the material showed improved shielding behavior, which was attributed to its high density and atomic number. At 59.9 keV, RPE increased from 6.9% for the pure polymer to 12.2% for the 6 wt.% composite, whereas MFP decreased from 13.9 cm to 7.6 cm. The results indicate that ZnO addition significantly enhances the shielding efficiency of Benecel K4M, demonstrating that ZnO can serve as a lightweight and non-toxic alternative to heavy-metal-based materials for pharmaceutical protection in radiation-rich environments. Full article

Buildings consume 40% of global energy, over half of which is used for cooling and heating. Tungsten bronze (M_xWO₃) holds promise for smart windows due to its ability to block near-infrared (NIR) heat radiation while maintaining visible light transmittance. However, conventional high-temperature synthesis is energy intensive. Here, we develop a low-temperature hydrothermal method (170 °C) to prepare Li and Cs co-doped tungsten oxide using WCl₆, LiF, and CsOH·H₂O as precursors, with acetic acid as a crystallographic modulator. The material exhibits a hexagonal structure (P6₃/mcm) and Li⁺-induced lattice expansion (0.34 nm spacing). Combined XPS and ICP-OES analyses confirm the chemical composition as Cs_0.31Li_0.09WO₃ and reveal a positive correlation between the W⁵⁺ content (15.76%) and oxygen vacancy concentration, which is identified as the key factor enhancing the NIR absorption. The material demonstrates excellent visible light transmission and NIR shielding properties. Our work provides a more energy-efficient and sustainable pathway for the production of smart window materials. Full article

The proliferation of wireless networking solutions, which are omnipresent in our daily lives, has led to increased exposure to the energy of electromagnetic (EM) waves in the higher frequency range, raising concerns about their impact on human health. Investigating the propagation of EM waves through multilayer structures can shed light on the future direction of effective protection and shielding solutions. The paper provides a comparative study that examines EM wave propagation through a multilayered composite structure. The structure combines Plexiglas plates (acrylic, polymethyl methacrylate), a dielectric material, with one or more layers of conductive YSHIELD HSF54 paint to reduce EM field intensity. The paint’s carbon-based particle composition promises effective field attenuation. Our side-by-side comparative real-world measurements and simulation results showcase correlation. We further demonstrated the benefits of applying a layer of conductive YSHIELD HSF54 paint over Plexiglass to form a composite structure, with the initial layer contributing to attenuation of approximately 20 dB. Finally, the results were validated by calculating Morozov’s first- and second-order analytical approximations for the transmission parameter $S_{21}$—the calculated values accurately trace both the simulations and measurements. The research concludes that shielding, which is used as a method of protection against EM radiation in many industrial devices, can also be used in procedures to protect human habitats by selecting new, innovative, and affordable materials and structures. Full article

Solar radiation and snow accumulation are the two important factors impacting thermal states of the permafrost beneath embankments with asphalt pavement in the Arctic regions, which can threaten the stability of permafrost and thus operation safety. In this study, we adopted the numerical simulation method to evaluate and compare the cooling performance of the proposed three types of embankments, namely, grey near-infrared reflective coating embankment, sun/snow shield embankment, and grey near-infrared reflective coating–sun/snow shield embankment, thereby mitigating the effect of the solar radiation and snow accumulation in the Arctic regions. Results show that (1) the grey near-infrared reflective coating mainly cools permafrost underlying the asphalt pavement and cannot mitigate thermal imbalance issue of two sides in embankment (shady–sunny slope effect), while the sun/snow shield embankment mainly cools the permafrost under two side slopes and can significantly mitigate shady–sunny slope effect; (2) grey near-infrared reflective coating–sun/snow shield embankment can not only effectively cools the permafrost beneath the embankment but also addresses the shady–sunny slope effect; (3) these three proposed types of embankments can significantly increase the permafrost table under sunny slope by 25.25%, 72.41%, and 76.94%, under asphalt pavement by 70.85%, 65.02%, and 81.91%, and under shady slope by 41.07%, 63.40%, and 69.42%. This study contributes to the design, construction, and maintenance of permafrost embankments in Arctic regions. Full article

Building energy conservation through the development of transparent thermal insulation materials that selectively block near-infrared radiation while maintaining visible light transmittance has emerged as a key strategy for global carbon neutrality. WO₃ is a semiconductor oxide with near-infrared absorption capabilities. However, the limited absorption efficiency and narrow spectral coverage of pure WO₃ significantly diminish its overall transparent thermal insulation performance, thereby restricting its practical application in energy-saving glass. Therefore, this study successfully prepared Sn-doped WO₃ materials using a one-step hydrothermal method, controlling the Sn:W molar ratio from 0.1:1 to 2.0:1. Through evaluation of transparent thermal insulation performance of a series of Sn-doped WO₃ samples, we found that Sn:W = 0.9:1 exhibited the most excellent performance, with NIR shielding efficiency reaching 93.9%, which was 1.84 times higher than pure WO₃. Moreover, this sample demonstrated a transparent thermal insulation index (THI) of 4.38, representing increases of 184% and 317%, respectively, compared to pure WO₃. These enhancements highlight the strong NIR absorption capability achieved by Sn-doped WO₃ through structural regulation. When Sn doping reaches a certain concentration, it triggers a structural transformation of WO₃ from monoclinic to tetragonal phase. After reaching the critical solubility threshold, phase separation occurs, forming a multiphase structure composed of a Sn-doped WO₃ matrix and secondary SnO₂ and WSn_0.33O₃ phases, which synergistically enhance oxygen vacancy formation and W⁶⁺ to W⁵⁺ reduction, achieving excellent NIR absorption through small polaron hopping and localized surface plasmon resonance effects. This study provides important insights for developing high-performance transparent thermal insulation materials for energy-efficient buildings. Full article

Addressing the challenge of synergistically optimizing shielding performance and mechanical properties in nuclear radiation shielding materials, this study designed and prepared as-cast Mg-12Dy-xSm-0.4Zr (x = 1, 2, 3) alloys by incorporating rare earth elements Dy and Sm, which possess high thermal neutron absorption cross-sections. The co-addition of Sm and Dy significantly refined the grains and promoted the precipitation of bone-like Mg₅(Sm,Dy) and Mg₄₁Sm₅ phases along grain boundaries. The alloys exhibited favorable mechanical properties, with ultimate tensile strength (UTS) reaching up to 194.6 MPa and elongation (EL) up to 10.9%. However, higher Sm content led to an increased amount of secondary phases at grain boundaries, resulting in stress concentration and a subsequent decline in both yield strength and elongation. Moreover, the combined addition of Dy and Sm markedly enhanced the thermal neutron shielding performance. Experimental results agreed well with Geant4 simulations, showing that both the neutron shielding rate and linear attenuation coefficient improved with increasing Sm content, demonstrating the positive role of Dy and Sm in neutron absorption. The developed alloy achieves simultaneous improvement in mechanical properties and neutron shielding capacity, providing valuable insights for the development of lightweight “function–structure integrated” radiation shielding materials for applications such as nuclear medicine and aerospace. Full article

The growing demand for radiation-shielded infrastructure highlights the need for materials that balance shielding performance with environmental and economic sustainability. Heavyweight self-compacting concretes (HWSCC), commonly produced with barite (BaSO₄) or magnetite (Fe₃O₄) aggregates, lack systematic life cycle comparisons. The aim of this study is to systematically compare barite- and magnetite-based HWSCC in terms of life cycle environmental impacts, life cycle cost, functional performance (strength and shielding), and end-of-life circularity, in order to identify the more sustainable and cost-effective material for radiation shielding infrastructure. This study applies cradle-to-grave life cycle assessment (LCA) and life cycle cost analysis (LCC), in accordance with ISO 14040/14044 and ISO 15686-5, to evaluate barite- and magnetite-based HWSCC. Results show that magnetite concrete reduces global warming potential by 19% eutrophication by 24%, and fossil resource depletion by 23%, while lowering life cycle costs by ~23%. Both concretes achieve comparable compressive strength (~48 MPa) and shielding efficiency (µ ≈ 0.28–0.30 cm⁻¹), meeting NCRP 147 and IAEA SRS-47 standards. These findings demonstrate that magnetite-based HWSCC offers a more sustainable, cost-effective, and ethically sourced alternative for radiation shielding in healthcare, nuclear, and industrial applications. In addition, the scientific significance of this work lies in establishing a transferable methodological framework that combines LCA, LCC, and performance-normalized indicators. This enables scientists and practitioners worldwide to benchmark heavyweight concretes consistently and to adapt sustainability-informed material choices to their own regional contexts. Full article

Background/Objectives: This study investigates the dosimetric impact of a 3D-printed applicator integrating multilayer catheter geometry and high-density shielding, designed for contact interventional radiotherapy (IRT) in non-melanoma skin cancer (NMSC) treatment. The aim is to assess its potential to enhance target coverage and reduce doses in organs at risk (OARs). Methods: A virtual prototype of a multilayer applicator was designed using 3D modeling software and realized through fused deposition modeling. Dosimetric simulations were performed using both TG-43 and TG-186 formalisms on CT scans of a water-equivalent phantom. A five-catheter array was reconstructed, and lead-cadmium-based alloy shielding of varying thicknesses (3–15 mm) was contoured. CTVs of 5 mm and 8 mm thickness were analyzed along with a neighboring OAR. Dosimetric endpoints included V95%, V100%, V150% (CTV), D_2cc (OAR), and therapeutic window (TW). Results: Compared to TG-43, the TG-186 algorithm yielded lower OAR doses while maintaining comparable CTV coverage. Progressive increase in shielding thickness led to improved V95% and V100% values and a notable reduction in OAR dose, with an optimal trade-off observed between 6 and 9 mm of shielding. The TW remained above 7 mm across all configurations, supporting its use in lesions thicker than conventional guidelines recommend. Conclusions: The integration of multilayer catheter geometry with high-density shielding in a customizable 3D-printed applicator enables enhanced dose modulation and OAR sparing in superficial IRT. This approach represents a step toward personalized brachytherapy, aligning with the broader movement in radiation oncology toward patient-specific solutions, adaptive planning, and precision medicine. Future directions should include prototyping and mechanical testing of the applicator, experimental dosimetric validation in phantoms, and pilot clinical feasibility studies to translate these promising in silico results into clinical practice. Full article

In urban heat islands with sun-exposed roofs, the cooling potential of unfinished attics is often insufficient. Attics and the adjacent floor often overheat and do not cool sufficiently during tropical nights. Because of heritage-preservation requirements and limited structural reserve in historic roof constructions, it is often not possible to install heat-dissipating photovoltaic modules or add a superimposed cold-roof assembly above the existing roof skin. A possible solution is ‘infrared (IR) shading’, which uses interior IR-shading elements to shield long-wave radiation from the solar-heated roof skin. The research had two goals: (i) develop and evaluate lightweight IR-shading elements that can be reversibly mounted at rafter level on the attic side; and (ii) investigate how rafter-field ventilation can remove heat from the IR-shading elements. Full article

The potential health risks of DC charging piles to human health were investigated by quantifying the internal electromagnetic exposure level. In this study, the transformer in the DC/DC circuit of a DC charging pile was selected as the radiation source, and two realistic human models (adult and child) were used as exposure subjects. A simulation model, including the vehicle body, charging pile, and transformer, was established using COMSOL(COMSOL Multiphysics 6.2) Multiphysics software to calculate the magnetic induction intensity (B-field) and electric field intensity (E-field) in various organs at distances of 0.1 m, 0.3 m, and 0.6 m from the charging pile. The results show that at 0.1 m, the peak B-field (1.91 µT) and E-field (447 mV/m) in the adult body were 1.91% and 2.07% of the ICNIRP occupational exposure limits, respectively, and 7.07% and 4.14% of the public exposure limits. For the child model, the peak electromagnetic exposure levels (2.31 µT and 259 mV/m) were only 8.56% and 2.40% of the public limits. Further evaluation of exposure levels for in-vehicle occupants during charging showed that the peak B-field and E-field for an adult driver and a child in the front passenger seat were 0.0225 × 10⁻² µT, 0.0237 × 10⁻² µT, 5.81 mV/m, and 5.82 mV/m, respectively, far below the ICNIRP public limits. Additionally, analyses at multiple frequency bands (85 kHz, 90 kHz, and 95 kHz) under a typical scenario (adult at 0.1 m from the charging pile) revealed that the B-field in the human body decreased with increasing frequency, while the E-field showed minimal variation due to shielding effects. All electromagnetic exposure levels were below both ICNIRP public and occupational limits, indicating the broad applicability of the results. Under normal operating conditions of DC charging piles, the electromagnetic exposure from the DC/DC transformer fully complies with safety standards and poses no threat to human health. This study provides a scientific basis for alleviating public concerns about the health risks of electromagnetic radiation from DC charging piles for electric vehicles. Full article

Background: Radiation exposure in the cardiac catheterization laboratory remains a critical occupational hazard for interventional cardiologists and staff, contributing to orthopedic injuries, cataracts, and malignancy. In parallel, procedural complexity continues to increase, demanding both precision and safety. Robotic-assisted percutaneous coronary intervention (R-PCI), alongside advanced shielding systems and imaging integration, has emerged as a transformative strategy to minimize radiation and enhance operator ergonomics. Objective: This state-of-the-art review synthesizes the current clinical evidence and technological advances that support a radiation-reduction paradigm in percutaneous coronary intervention (PCI), with a particular focus on the role of R-PCI platforms, procedural modifications, and emerging shielding technologies. Methods: We reviewed published clinical trials, registries, and experimental studies evaluating robotic PCI platforms, contrast and radiation dose metrics, ergonomic implications, procedural efficiency, and radiation shielding systems. Emphasis was given to the integration of CT-based imaging (coronary computed tomography angiography—CCTA, fractional flow reserve computed tomography—FFR-CT) and low-dose acquisition protocols. Results: R-PCI demonstrated technical success rates of 81–100% and clinical success rates up to 100% in both standard and complex lesions, with significant reductions in operator radiation exposure (up to 95%) and procedural ergonomic burden. Advanced shielding technologies offer radiation dose reductions ranging from 86% to nearly 100%, while integration of (CCTA), (FFR-CT), and Artificial Intelligence (AI) -assisted procedural mapping facilitates further fluoroscopy minimization. Robotic workflows, however, remain limited by lack of device compatibility, absence of haptic feedback, and incomplete integration of physiology and imaging tools. Conclusions: R-PCI, in combination with shielding technologies and imaging integration, marks a shift towards safer, radiation-minimizing interventional strategies. This transition reflects not only a technical evolution but a philosophical redefinition of safety, precision, and sustainability in modern interventional cardiology. Full article