Feasibility of nanomaterial tungsten carbide as lead-free nanomaterial-based radiation shielding

Promising application of nano-WO3/epoxy composite in intensity-modulated brachytherapy: a simulation study

PURPOSE

Implementing intensity-modulated brachytherapy (IMBT) techniques with high-energy sources like 60Co has always been challenging due to the clinical limitations of the applicator dimensions. This study aims to investigate using tungsten trioxide nanoparticles/epoxy composite as a shielding material to enhance the protective properties of a redesigned applicator.

MATERIALS AND METHODS

The Geant4 application to tomographic emission, the Geant4-based Monte Carlo dose calculation engine (version 9.0), was used to simulate the shielding composite and the IMBT technique with a voxelated patient-based phantom. To evaluate the effectiveness of the new shielding material, IMBT plans created with the redesigned applicator were compared with those with a conventional applicator. 60Co and 192Ir were utilized, and in the same high-risk clinical target volumes D90, the D2cc for the bladder and rectum were evaluated in 18 patients with vaginal cancer.

RESULTS

For the IMBT plans with the 60Co source, the use of the redesigned applicator decreased the D2cc of the bladder and rectum by 11.1% and 12.8%, respectively, while for those with the 192Ir source, the reduction was 16.6% and 18.7%, respectively. Nevertheless, there was an insignificant alteration in the absorbed dose parameter (D90) for the target using both sources.

CONCLUSION

This study demonstrates that tungsten trioxide nanoparticle/epoxy composite can be advantageous in tackling radiation shielding concerns. Enhancing the shielding properties of this composite, considering the size limitations of applicators, leads to improved protection of organs at risk, such as the bladder and rectum. This substance can be considered a promising shielding material in the construction of applicators.

X-Ray Shielding Polymer Based on Sequential Polycondensation of BiPh3 and Carboxylic Acids and Radical Polymerization

Transparent X-ray shielding polymer films were developed by bulk photo copolymerization of in situ prepared bismuth carboxylate prepolymers with polymerizable exomethylene moieties and N,N-dimethylacrylamide (DMAA). The bismuth-containing prepolymers were prepared via the polycondensation of BiPh3, 2-octenylsuccinic acid (OSA), and itaconic acid (IA) bearing an exomethylene group for polymerization. OSA was a chain extender by intermolecular condensation and a stopper by intramolecular cyclization to inhibit cross-linkage. The resulting photocured films exhibit high visible-light transparency and high nD, reaching 1.57. The X-ray shielding ability increased with the bismuth content and reached an aluminum equivalent of 0.80.

Experimental Analysis of the Machinability of 94 WC-6 Co by Die-Sinking EDM

Cobalt-bonded tungsten carbide (WC-Co) is widely used in heavy-duty machining applications due to its exceptional hardness and wear resistance, and it is increasingly being adopted in industries such as aerospace and the automotive sector, among others. Its superior mechanical properties make it difficult to machine with conventional methods such as turning or milling. Electrical Discharge Machining (EDM) has emerged as an efficient alternative, as it allows for the machining of hard materials to be carried out without direct contact between the tool and the workpiece, provided that the material has sufficient electrical conductivity. In this study, a multilevel Design of Experiments (DOE) was conducted to analyze the influence of EDM parameters-specifically, the current intensity and pulse time-on the surface roughness (SR), electrode wear (EW), and material removal rate (MRR) for 94WC-6Co. The results indicate that the current intensity was the most significant factor across all responses, while the pulse time played a secondary role. Surface finishes as low as Ra = 0.47 μm were achieved at I = 2 A and ti = 10 μs. For each outcome variable, mathematical models were obtained in order to improve the EDM processes and better understand the machining of WC-Co.

Comparison of X-Ray Attenuation Performance, Antimicrobial Properties, and Cytotoxicity of Silicone-Based Matrices Containing Bi2O3, PbO, or Bi2O3/PbO Nanoparticles

Background

Application of the nanomaterials to preparing X-ray shields and successfully treating multiresistant microorganisms has attracted great attention in modern life.

Objective

This study aimed to prepare flexible silicone-based matrices containing Bi2O3, PbO, or Bi2O3/PbO nanoparticles and select a cost-effective, cytocompatible, and antibacterial/antifungal X-ray shield in clinical radiography.

Material and Methods

In this experimental study, we prepared the nanoparticles by the modified biosynthesis method and fabricated the X-ray shields containing 20 wt% of the nanoparticles. The X-ray attenuation percentage and Half Value Layer (HVL) of the shields were investigated for the photon energies in the range of 40-100 kVp in clinical radiography. The antibacterial/antifungal activities of the shields were evaluated using a colony count method for the gram-negative (Escherichia coli), and gram-positive (Enterococcus faecalis) bacteria, and Candida albicans fungus. The shield toxicity was investigated on A549 cells.

Results

The highest X-ray attenuation percentage and the lowest HVL were obtained using the shield containing Bi2O3 nanoparticles. Although all shields displayed antimicrobial activity, the shield containing Bi2O3/PbO nanoparticles showed the most effective reduction in the colony counts. Both X-ray shields containing nano Bi2O3 and Bi2O3/PbO demonstrated high cytocompatibility on A549 cells at a concentration as high as 500 µg/ml. The shield with PbO nanoparticles was also cytocompatible at a concentration of 50 µg/ml.

Conclusion

The best X-ray attenuation performance is attributed to the silicone-based matrix with nano Bi2O3; however, the flexible shield with Bi2O3/PbO nanoparticles can be cost-effective and cytocompatible with the best antibacterial/antifungal properties.

Monte Carlo dosimetry study of newly designed shielded applicators for intensity modulated brachytherapy of cervical and vaginal cancers

INTRODUCTION

The utilization of metal shields in intensity-modulated brachytherapy (IMBT) enables the modulation of the dose, resulting in improved conformance to the tumor while simultaneously reducing the doses to organs at risk (OARs). Utilizing higher-energy sources like 60Co in IMBT for cervical and vaginal cancers has consistently posed challenges. This study evaluates the dosimetric aspects of modified applicators designed for IMBT using 60Co and 192Ir sources.

MATERIALS AND METHODS

GATE, a Geant4-based simulation code, was utilized to model and simulate four distinct applicators. The clinical applicators were redesigned to place the structure of the source tube and the shield while keeping the general characteristics unchanged. These shields were evaluated by calculating transmission factors (TFs) and the dose homogeneities were also determined.

RESULT

Transmission factors for the IMBT technique in redesigned intrauterine applicators and tungsten shields for iridium and cobalt sources were at least 12.8 and 65.4%, and these values were obtained for the intravaginal applicator at 0.2 and 7.0%, respectively. The dose homogeneities for all combinations of radionuclide-shield were within a 15% range of the non-IMBT applicators.

CONCLUSION

This study has quantitatively evaluated the dosimetric effect of tungsten shields in the IMBT technique for cervical and vaginal cancer using cobalt sources. 192Ir compared to 60Co resulted in higher effectiveness for the designed intrauterine and intravaginal shields. while implementing tungsten shields in the redesigned applicators against the 60Co source may not offer complete protection, it does show promising results in reducing the dose to organs at risk.

Role of green and sustainable practices in shaping the future of medical imaging technology: A cross-sectional multi-stakeholder analysis among students, radiographers, and academic experts

INTRODUCTION

The detection and treatment of diseases like COVID, diabetes, cancer, cardiovascular conditions, etc., have made medical imaging technology more necessary, so it is expected that the demands of imaging modalities are also increasing and are major contributors to carbon emissions in the healthcare industry. Hence, the Radiology departments, like the rest of the healthcare industry should adapt the procedures to become more sustainable.

METHODS

A total of 1016 respondents completed the online survey to assess the perception, current practices, and challenges in adopting green and sustainable practices in medical imaging. The radio technologists, teaching faculties, and students of medical imaging were recruited for the study. The survey tool was distributed to the closed groups through social media and emails.

RESULTS

The majority of participants (66.6%) highlighted the importance of green and sustainable practices in medical imaging whereas only 21.06% of participants seem to have implemented these practices. Most of the participants give positive responses on the use of zero-lead aprons (77%), refurbished medical systems (85.8%), and eco-friendly packaging (89.5%). The mixed response was received from waste segregation and energy-saving measures. The majority (60.3%) of them have no formal education or training. However, they have a good attitude towards the willingness to adopt green practices.

CONCLUSIONS

There is a gap between perception and implementation of green and sustainable practices due to leadership and information barriers. Comprehensive training for stakeholders of medical imaging is crucial to fully integrate sustainability practices, possibly through webinars or educational modules.

IMPLICATIONS FOR PRACTICE

The study's findings shed light on how important medical imaging stakeholders view green and sustainable practices as well as potential obstacles to their implementation at the local level whilst suggesting the need for exclusive training on these practices to promote sustainability.

Fabrication, Structural Characterization, and Photon Attenuation Efficiency Investigation of Polymer-Based Composites

Experiments have assessed various polymer composites for radiation shielding in diverse applications. These composites are lighter and non-toxic when compared to lead (Pb), making them particularly effective in diagnostic imaging for shielding against low-energy photons. This study demonstrates the fabrication of four composites by combining a base material, specifically a high-density polyethylene (HDPE) polymer, with 10% and 20% silicon (Si) and silicon carbide (SiC), respectively. Additionally, 5% molybdenum (Mo) was incorporated into the composites as a heavy metal element. The composites obtained were fabricated into 20 disks with a uniform thickness of 2 mm each. Discs were exposed to radiation from a low-energy X-ray source (32.5-64.5 keV). The chemical and physical properties of composites were assessed. The shielding ability of samples was evaluated by determining the linear and mass attenuation coefficients (μ and μm), radiation protection efficiency (RPE), half-value layer (HVL), and mean free path (MFP). According to our findings, supplementing HDPE with additives improved the attenuation of beams. The μm values showed that composite X-ray shielding characteristics were enhanced with filler concentration for both Si and SiC. Polymer composites with micro-molecule fillers shelter X-rays better than polymers, especially at low energy. The HVL and MFB values of the filler are lower than those of the pure HDPE sample, indicating that less thickness is needed to shield at the appropriate energy. HC-20 blocked 92% of the incident beam at 32.5 keV. This study found that increasing the composite sample thickness or polymer filler percentage could shield against low-energy radiation.

Microstructure investigation, Electrical properties, and γ-rays' protection capacity for ZnO doped clay ceramic

A series of ceramic samples fabricated based on ZnO doped different concentrations of natural clay according to the relation (1-x) ZnO - (x) clay; 5 wt% ≤ x ≤ 20 wt%. The samples were pressed and sintered at 1200 °C. The experimental techniques were used to characterize and measure the chemical composition, density, and current-voltage measurements for the fabricated ceramics samples. The measurements depict an increase in the I-V nonlinearity with raising the clay concentration, where the increase in clay by up to 20 wt% shifts breakdown voltage to a higher value of up to 390 V/cm and decreases leakage current to 55 mA/cm2. The examinations for the gamma-ray shielding capacity for the fabricated composites (utilizing Monte Carlo simulation) demonstrate enrichment of clay concentration between 5 wt% and 20 wt% reduced the linear attenuation coefficient for the fabricated ceramics by 23.15% and 8.66% at γ photon energy of 0.059 MeV and 1.252 MeV, respectively. The half-value thickness and lead's equivalent thickness increased along with a drop in the linear attenuation coefficient, but the radiation protection effectiveness of the fabricated ceramics increased.

An extensive assessment of the impacts of BaO on the mechanical and gamma-ray attenuation properties of lead borosilicate glass

The current work deals with the synthesis of a new glass series with a chemical formula of 5Al2O3-25PbO-10SiO2-(60-x) B2O3-xBaO; x was represented as 5, 10, 15, and 20 mol%. The FT-IR spectroscopy was used to present the structural modification by rising the BaO concentration within the synthesized glasses. Furthermore, the impacts of BaO substitution for B2O3 on the fabricated borosilicate glasses were investigated using the Makishima-Mackenzie model. Besides, the role of BaO in enhancing the gamma-ray shielding properties of the fabricated boro-silicate glasses was examined utilizing the Monte Carlo simulation. The mechanical properties evaluation depicts a reduction in the mechanical moduli (Young, bulk, shear, and longitudinal) by the rising of the Ba/B ratio in the fabricated glasses. Simultaneously, the micro-hardness boro-silicate glasses was reduced from 4.49 to 4.12 GPa by increasing the Ba2+/B3+ ratio from 0.58 to 3.18, respectively. In contrast, the increase in the Ba/B ratio increases the linear attenuation coefficient, where it is enhanced between 0.409 and 0.448 cm-1 by rising the Ba2+/B3+ ratio from 0.58 to 3.18, respectively. The enhancement in linear attenuation coefficient decreases the half-value thickness from 1.69 to 1.55 cm and the equivalent thickness of lead is also reduced from 3.04 to 2.78 cm, at a gamma-ray energy of 0.662 MeV. The study shows that the increase in the Ba2+/B3+ ratio enhances the radiation shielding capacity of the fabricated glasses however, it slightly degrades the mechanical properties of the fabricated glasses. Therefore, glasses with high ratios of Ba2+/B3+ have high gamma-ray shielding ability to be used in hospitals as a shielding material.

The Development of a Composite Thin Film Barrier of Tungsten Fe3O4-rGO (FerGO) for the Radiation Shielding of Medical Personnel

Tungsten is the most effective eco-friendly material used for radiation shielding in hospitals. However, despite its commendable density and shielding performance, tungsten faces challenges in miscibility with other materials because of its elevated melting point and strength. In this study, to protect medical personnel against scattered rays, which are indirect X-rays, a lightweight material was prepared by mixing graphite oxide material, considering its thinness and flexibility. Tungsten particles were evenly dispersed in the polymer, and nanofibers were prepared using this blended polymer solution via electrospinning. Concurrently, the process technology was explored to craft a thin film sheet and obtain a lead-like shielding effect. A spinning solution was prepared by mixing Fe3O4-rGO (FerGO) and tungsten. At 60 kVp, 0.1 mm was measured as 0.097 mmPb, at 80 kVp, 0.2 mm was measured as 0.196 mmPb, and at 100 kVp, 0.3 mm was measured as 0.279 mmPb, showing similar shielding performance to lead. As density directly affects the shielding effect, graphene oxide played an important role in increasing the density of the material from 1.941 g/cm3 to 2.302 g/cm3. Thus, this study provides an effective process for producing thin film sheets equivalent to lead.

Medical-Radiation-Shielding Film Fabricated by Imitating the Layered Structure Pattern of Abalone Shell and Verification of Its Shielding Effect

Radiation-shielding clothing for medical workers must be light and thin, thus ensuring flexibility. However, controlling the thickness and weight is limited by shielding performance requirements. This study aims to improve shielding performance by considering a shielding structure that mimics the internal structure of an abalone shell. Two shields were produced: a sheet made with a carrier process using a liquid polymer and tungsten mixture, and a fillet made by compounding the same material and laminated using a heat-treatment press after the injection process. The tungsten content and thickness were the same at 85 wt% and 0.3 mm, respectively. In the high-energy region, the shielding film based on the laminated structure of abalone shells showed a shielding rate that was higher by more than 7%. Compared to that of a 0.3 mm lead plate, the shielding ratio of the shielding film was approximately 16% lower at 120 kVp, thereby confirming the radiation-shielding effect of the layered-structure shielding film. Therefore, it is concluded that the laminated structure of the shielding film, which is identical to the internal laminated structure of the abalone shell, expands the impact area of incident radiation and attenuates the energy intensity, thereby improving the medical-radiation-shielding performance.

Medical-Grade PLA Nanocomposites with Optimized Tungsten Carbide Nanofiller Content in MEX Additive Manufacturing: A Rheological, Morphological, and Thermomechanical Evaluation

The goal of this paper is to investigate tungsten carbide (WC) as a reinforcement in the popular material extrusion (MEX) additive manufacturing (AM) procedure. The impressive characteristics of WC demonstrate its potential as a valuable additive for commonly used polymeric matrices in MEX 3D printing, offering reinforcement and stabilization properties. The mechanical properties of hybrid polymer/ceramic nanocomposites made up of various filler loadings (0-10 wt. %) of medical-grade polylactic acid (PLA) and WC were studied. The mechanical characteristics, structure, and thermomechanical properties of the resulting compounds were fully characterized following the respective standards. The fracture mechanisms were revealed with Scanning Electron Microscopy. Overall, a laborious effort was implemented with fifteen different tests to fully characterize the nanocomposites prepared. In comparison to the raw PLA material, the tensile strength of the 4.0 wt. % WC PLA/WC nanocomposite was improved by 42.5% and the flexural strength by 41.9%. In the microhardness test, a 120.4% improvement was achieved, justifying the properties of WC ceramic. According to these findings, PLA nanocomposites reach high-performance polymer specifications, expanding their potential use, especially in wear-related applications.

The Cytotoxicity of Tungsten Ions Derived from Nanoparticles Correlates with Pulmonary Toxicity

Tungsten carbide nanoparticles (nano-WC) are prevalent in composite materials, and are attributed to their physical and chemical properties. Due to their small size, nano-WC particles can readily infiltrate biological organisms via the respiratory tract, thereby posing potential health hazards. Despite this, the studies addressing the cytotoxicity of nano-WC remain notably limited. To this purpose, the BEAS-2B and U937 cells were cultured in the presence of nano-WC. The significant cytotoxicity of nano-WC suspension was evaluated using a cellular LDH assay. To investigate the cytotoxic impact of tungsten ions (W⁶⁺) on cells, the ion chelator (EDTA-2Na) was used to adsorb W⁶⁺ from nano-WC suspension. Subsequent to this treatment, the modified nano-WC suspension was subjected to flow cytometry analysis to evaluate the rates of cellular apoptosis. According to the results, a decrease in W⁶⁺ could mitigate the cellular damage and enhance cell viability, which indicated that W⁶⁺ indeed exerted a significant cytotoxic influence on the cells. Overall, the present study provides valuable insight into the toxicological mechanisms underlying the exposure of lung cells to nano-WC, thereby reducing the environmental toxicant risk to human health.

Assessment of Silicone Rubber/Lead Oxide Composites Enriched with Bi2O3, WO3, BaO, and SnO2 Nanoparticles for Radiation Shielding Applications

This study aimed to prepare silicone rubber composites with heavy metal oxide nanoparticles for gamma ray shielding applications. Different heavy metal oxide nanoparticles were incorporated into the silicone rubber matrix, and the prepared composites were characterized for their thermal, mechanical, and radiation shielding properties. The density of the prepared SR samples ranged from 1.25 to 2.611 g·cm^-3, with SR-2 having the highest density due to the presence of lead oxide. Additionally, the thermal stability of the materials improved with the addition of HMO nanoparticles, as indicated by TGA results. The prepared SR materials showed ultimate deformation displacement ranging from 14.17 to 21.23 mm, with the highest value recorded for SR-3 and the lowest for SR-2. We investigated the transmission factor (TF) of gamma rays through silicone rubber (SR) composites with different heavy metal oxide (HMO) nanoparticles. The addition of HMOs resulted in a decrease in TF values, indicating improved radiation shielding performance. The TF was found to be lowest in SR-5, which contained 15% of Bi₂O₃, WO₃, BaO, and Zr₂O₃ each. The linear attenuation coefficient (LAC) of the SR samples was also evaluated, and it was found that the incorporation of HMOs increased the probability of photon interactions, leading to improved radiation protection effectiveness. The half-value layer (HVL) of the SR samples was also examined, and it was found that the addition of HMOs resulted in a significant reduction in HVL values, particularly at low energy levels. SR-5 had the lowest HVL among the group, while SR-2, SR-3, and SR-4 had higher HVL values. These results demonstrate the effectiveness of using HMOs in enhancing the radiation shielding properties of SR composites, particularly for low-energy gamma rays.

Organ distribution of Nano-WC particles after repeated intratracheal instillation into the lungs of SD rats and subsequent organ injury

Nano-tungsten carbide (nano-WC) is widely used in composite materials due to its special physical and chemical properties. Owing to their small size, nano-WC nanoparticles easily enter organisms through the respiratory tract, which may cause health hazards. However, only a few studies have reported the toxicity of nano-WC. In this study, a 10 mg/kg nano-WC suspension and 0.9% normal saline were quantitatively perfused into the lungs of two groups of healthy male SD rats by tracheal instillation, and the in vivo pulmonary toxic effects were systematically evaluated. Additionally, as multiple organs and tissues are involved, systemic effects were observed throughout the body and mainly manifested as inflammatory damage. The concentrations of tungsten ions in various organs and alveolar lavage fluid were measured by ICP-MS, and the results showed that the lung was the target organ, as it had the highest concentration of ions. In addition, the abnormal increases in the tungsten ion concentrations in the liver and kidney may be closely related to the immune damage we observed. This study provides a theoretical basis and data support for the systematic evaluation of the health hazards of nano-WC and a reference for the safe use of nanomaterials.

Recent Metal Nanotheranostics for Cancer Diagnosis and Therapy: A Review

In recent years, there has been an increasing interest in using nanoparticles in the medical sciences. Today, metal nanoparticles have many applications in medicine for tumor visualization, drug delivery, and early diagnosis, with different modalities such as X-ray imaging, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), etc., and treatment with radiation. This paper reviews recent findings of recent metal nanotheranostics in medical imaging and therapy. The study offers some critical insights into using different types of metal nanoparticles in medicine for cancer detection and treatment purposes. The data of this review study were gathered from multiple scientific citation websites such as Google Scholar, PubMed, Scopus, and Web of Science up through the end of January 2023. In the literature, many metal nanoparticles are used for medical applications. However, due to their high abundance, low price, and high performance for visualization and treatment, nanoparticles such as gold, bismuth, tungsten, tantalum, ytterbium, gadolinium, silver, iron, platinum, and lead have been investigated in this review study. This paper has highlighted the importance of gold, gadolinium, and iron-based metal nanoparticles in different forms for tumor visualization and treatment in medical applications due to their ease of functionalization, low toxicity, and superior biocompatibility.

Views on Radiation Shielding Efficiency of Polymeric Composites/Nanocomposites and Multi-Layered Materials: Current State and Advancements

This article highlights advancements in polymeric composite/nanocomposites processes and applications for improved radiation shielding and high-rate attenuation for the spacecraft. Energetic particles, mostly electrons and protons, can annihilate or cause space craft hardware failures. The standard practice in space electronics is the utilization of aluminum as radiation safeguard and structural enclosure. In space, the materials must be lightweight and capable of withstanding extreme temperature/mechanical loads under harsh environments, so the research has focused on advanced multi-functional materials. In this regard, low-Z materials have been found effective in shielding particle radiation, but their structural properties were not sufficient for the desired space applications. As a solution, polymeric composites or nanocomposites have been produced having enhanced material properties and enough radiation shielding (gamma, cosmic, X-rays, protons, neutrons, etc.) properties along with reduced weight. Advantageously, the polymeric composites or nanocomposites can be layered to form multi-layered shields. Hence, polymer composites/nanocomposites offer promising alternatives to developing materials for efficiently attenuating photon or particle radiation. The latest technology developments for micro/nano reinforced polymer composites/nanocomposites have also been surveyed here for the radiation shielding of space crafts and aerospace structures. Moreover, the motive behind this state-of-the-art overview is to put forward recommendations for high performance design/applications of reinforced nanocomposites towards future radiation shielding technology in the spacecraft.