X-ray transmission through nanostructured and microstructured CuO materials

Enhanced radiation shielding efficiency of polystyrene nanocomposites with tailored lead oxide nanoparticles

In this study, we investigated a novel polymer nano-composite, PS-PbO, containing two distinct nano-sizes of lead oxide nanoparticles (PbO-A and PbO-B), in addition to the bulk size (PbO-K). These nanoparticles were embedded separately in a polystyrene (PS) matrix at different weight percentages (10%, 15%, 25%, and 35%) using roll mill mixing and compressing molding. Our evaluation focused on the radiation attenuation ability of PS-PbO and the effect of particle size, considering gamma-ray energies ranging from 0.06 to 1.3 MeV (from sources like 241Am, 133Ba, 137Cs, and 60Co). The linear attenuation coefficient (LAC) was determined by analyzing samples of the synthesized composite with different thicknesses. Then, various shielding parameters were calculated, including total molecular, atomic, and electronic cross-sections (σmol, σatm, σel), as well as the effective atomic number and the electron density (Zeff and Neff). Surprisingly, modifying PbO particle sizes had a significant impact on shielding efficiency. For instance, the composite with 25 wt% of the smallest PbO-B particles showed a 26.7% increase in LAC at 0.059 keV compared to the composite with 25 wt% of PbO-K (larger particles). Notably, the LAC peaked at low energy (0.059 keV), close to the K-edge of Pb, where interaction is directly proportional to Z4. With increasing PbO concentrations, the LAC of PS-PbO composites increased steadily. Additionally, as PbO concentration increased, the composite's effective atomic number Zeff and the electron density Neff increased, leading to a greater total Gamma-ray interaction cross-section. Furthermore, when comparing the Half-Value Layers of the novel nanocomposite to traditional lead shielding, a 70% reduction in mass was observed. Notably, the composite containing the smallest nano-size of PbO exhibited the highest radiation-shielding efficiency among all combinations and could therefore be used to create inexpensive and lightweight shields.

Development of Lead-Free Materials for Radiation Shielding in Medical Settings: A Review

Radiation protection is an essential issue in diagnostic radiology to ensure the safety of patients, healthcare professionals, and the general public. Lead has traditionally been used as a shielding material due to its high atomic number, high density, and effectiveness in attenuating radiation. However, some concerns related to the long-term health effects of toxicity, environmental disease as well as heavy weight of lead have led to the search for alternative lead-free shielding materials. Leadfree multilayered polymer composites and non-lead nano-composite shields have been suggested as effective shielding materials to replace conventional lead-based and single metal shields. Using several elements with high density and atomic number, such as bismuth, barium, gadolinium, and tungsten, offer significant enhancements in the shielding ability of composites. This review focuses on the development and use of lead-free materials for radiation shielding in medical settings. It discusses the drawbacks of traditional lead shielding, such as toxicity, weight, and recycling challenges, and highlights the benefits of lead-free alternatives.

Attenuation properties of hybrid nanocomposite film containing Ce2O, GO, and α-Al2O3 nanoparticles for high energy radiations

The use of diagnostic radiation in medical centers has spread due to the incidence of various diseases. Thus, it is essential that patients and medical staff wear protective clothing to protect themselves from their harmful effects. In the past, lead protective clothing has been used; however, the toxicity and heaviness of lead have limited the tendency to use these clothing. Recently, nanocomposites containing heavy element nanoparticles have been introduced as an alternative to lead coatings. In this study, hybrid nanocomposites containing ceria (CeO2), alumina (Al2O3), and graphene oxide (GO) nanoparticles were studied for this purpose. Ceria, alumina, and graphene oxide nanoparticles were mixed with polyethylenevinylacetate (EVA) dissolved in chloroform and casted on a glass plate to form nanocomposite films. The prepared nanoparticles and films were characterized by Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscope, Thermal Gravimetric Analysis, and Energy Dispersive X-ray Analysis, and then the attenuation properties of the films against high-energy radiation (120 kV) were studied in two narrow and broad beam geometries. The results showed that hybrid films, despite having a lower percentage of nanoparticles, showed better attenuation properties, which indicated the synergistic effect of nanoparticles with different mechanisms in attenuating the radiations. The attenuation ability of these films was considerable due to their lower density compared to lead. The fabricated hybrid nanocomposite films with a suitable performance in attenuation of high-energy radiations used in therapeutic diagnostics, can be proposed as a suitable alternative to conventional lead clothing.

Novel slag/natural rubber composite as flexible material for protecting workers against radiation hazards

This work is an attempt to employ the electric arc furnace (EAF) slag as a by-product material to develop an alternative and environmentally friendly material for gamma-radiation protection applications such as in medical and industrial areas. For this purpose, different concentrations of micro-sized EAF slag (0, 20, 40, 60, 80, 100, 500, and 800 phr) were incorporated as fillers in the natural rubber (NR) matrix to produce the shielding composites. In addition, nano-sized EAF slag particles were prepared by using a high-energy ball milling technique to investigate the effect of particle size on the gamma-radiation shielding properties. The synthesized micro and nano EAF/NR composites were tested as protective materials against gamma-radiation by employing NaI(Tl) scintillation detector and standard radioactive point sources (152Eu, 137Cs, 133Ba, and 60Co). Different shielding parameters such as linear and mass attenuation coefficient, half value layer (HVL), tenth value layer, mean free path, effective atomic number (Zeff), and effective electron density (Neff) were determined to assess the radiation shielding capability of the EAF/NR composites. Furthermore, equivalent atomic number (Zeq) and the exposure buildup factor values for photon energy in the range from 0.015 to 15 MeV were also computed by Geometric Progression method. The experimental results of micro EAF/NR composites showed that at 121.78 keV, EAF0 composite (without EAF slag content) had the lowest μ value of 0.1695 cm-1, while the EAF800 composite (which was loaded with 800 phr of micro EAF slag) had the highest μ value of 0.2939 cm-1 at the same energy, which in turn decreases the HVL from 4.09 to 2.36 cm, respectively. Therefore, increasing the filler weight fractions of EAF slag in the NR matrix, increases the shielding properties of the composites. Moreover, the NR composite reinforced with 800 phr of nano EAF slag has better gamma-radiation shielding efficiency compared to that filled with 800 phr of micro EAF slag. The success of this work was to prepare a flexible, lightweight, low-cost, and lead-free material with better shielding capability.

Investigation on Physico Chemical and X-ray Shielding Performance of Zinc Doped Nano-WO3 Epoxy Composite for Light Weight Lead Free Aprons

This report addresses a way to reduce the usage of highly toxic lead in diagnostic X-ray shielding by developing a cost-effective, eco-friendly nano-tungsten trioxide (WO₃) epoxy composite for low-weight aprons. Zinc (Zn)-doped WO₃ nanoparticles of 20 to 400 nm were synthesized by an inexpensive and scalable chemical acid-precipitation method. The prepared nanoparticles were subjected to X-ray diffraction, Raman spectroscopy, UV-visible spectroscopy, photoluminescence, high-resolution-transmission electron microscope, scanning electron microscope, and the results showed that doping plays a critical role in influencing the physico-chemical properties. The prepared nanoparticles were used as shielding material in this study, which were dispersed in a non-water soluble durable epoxy resin polymer matrix and the dispersed materials were coated over a rexine cloth using the drop-casting method. The X-ray shielding performance was evaluated by estimating the linear attenuation coefficient (μ), mass attenuation coefficient (μ_m), half value layer (HVL), and X-ray percentage of attenuation. Overall, an improvement in X-ray attenuation in the range of 40-100 kVp was observed for the undoped WO₃ nanoparticles and Zn-doped WO₃ nanoparticles, which was nearly equal to lead oxide-based aprons (reference material). At 40 kVp, the percentage of attenuation of 2% Zn doped WO₃ was 97% which was better than that of other prepared aprons. This study proves that 2% Zn doped WO₃ epoxy composite yields a better particle size distribution, μ_m, and lower HVL value and hence it can be a convenient lead free X-ray shielding apron.

Assessment of X-ray shielding properties of polystyrene incorporated with different nano-sizes of PbO

PbO (lead oxide) particles with different sizes were incorporated into polystyrene (PS) with various weight fractions (0, 10, 15, 25, 35%). These novel PS/PbO nano-composites were produced by roll mill mixing and compressing molding techniques and then investigated for radiation attenuation of X-rays (N-series/ISO 4037) typically used in radiology. Properties of the PbO particles were studied by X-ray diffraction (XRD). Filler dispersion and elemental composition of the prepared nano-composites were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), revealing better filler distribution and fewer agglomerations with smaller PbO particle size. Linear and mass attenuation coefficients (μ and μ_m), total molecular and atomic cross-sections (σ_mol and σ_atm), as well as effective atomic number and electron density (Z_eff and N_eff), were calculated for the energy range N40 to N200. The influence of PbO weight percentage on the enhancement of the shielding parameters of the nano-composites was expected; however, the effect of PbO particle size was surprising. Linear and mass attenuation coefficients for PS/PbO composites increased gradually with increasing PbO concentrations, and composites with a small size of nanoparticles showed best performance. In addition, increasing PbO concentration raised the effective atomic number Z_eff of the composite. Hence, the electron density N_eff increased, which provided a higher total interaction cross-section of X-rays with the composites. Maximum radiation shielding was observed for PS/PbO(B). It is concluded that this material might be used in developping low-cost and lightweight X-ray shielding to be used in radiology.

Dual-Energy Processing of X-ray Images of Beryl in Muscovite Obtained Using Pulsed X-ray Sources

This paper presents the development of a method for dual-energy processing of X-ray images using pulsed X-ray sources for the contrast detection of beryl in muscovite mica in 2D X-ray and CT images. These substances have similar chemical properties and are difficult to differentiate when one is against the background of the other using methods based on X-ray absorption. In the experiments, we used three pulsed X-ray sources with different maximum voltages. We performed modeling of the emission spectra and selection of the necessary energy bands due to X-ray absorbing filters: a positive effect was shown for dual-energy image processing when the function of converting X-ray radiation into a signal using the VIVIX-V 2323D detector was taken into account. As a result, a pulsed X-ray source with the pulse voltage of 330 kV was chosen for the contrast detection of beryl, with the content of 5-7% against the background of muscovite and the thickness up to 70 mm. Using this source and the developed mathematical algorithms, it is possible to obtain a band of low-energy radiation at the level of 70-80 keV, as well as high-energy radiation in the range of 180 keV. Methods based on the X-ray absorption can become both additional and independent methods for studying and monitoring membranes; these objects range from tens of nanometers to several micrometers in size.

Evaluation of Micro- and Nano-Bismuth(III) Oxide Coated Fabric for Environmentally Friendly X-Ray Shielding Materials

This research focuses on the development of environmentally friendly textile-based shielding composites, from micro-sized and nanosized Bi₂O₃ particles, against ionizing radiation. Polyester fabric dyne-coated with either micro- or nano-Bi₂O₃ particles shields some X-rays but the effectiveness is poor. With only ∼58% uptake of micro-sized Bi₂O₃ particles dyeing on polyester fabric, the insufficient amount of Bi₂O₃ leaded to the low density of particles, resulting in only 30% of X-ray shielding at 80 kVp. Cotton fabric coated with either micro- or nano-Bi₂O₃/poly(vinyl alcohol) (PVA) composites, on the other hand, demonstrated the capacity to attenuate X-ray generated by high diagnostic X-ray tube voltages of 70-100 kVp, in compliance with medical protection requirements. The X-ray attenuation performance of cotton fabric coated with either micro-Bi₂O₃/PVA or nano-Bi₂O₃/PVA nanocomposite decreased progressively with increasing tube acceleration voltages, however their ionizing radiation-shielding performance enhanced with the number of fabric layers. Interestingly, for all X-ray tube voltages evaluated, the micro-Bi₂O₃/PVA composite outperformed the nano- Bi₂O₃/PVA composite in terms of X-ray shielding. At a weight ratio of 66.7% Bi₂O₃, 10 layers of cotton fabric coated with micro- Bi₂O₃/PVA composite can attenuate 90, 85, and 80% of X-ray photons at 70, 80, and 100 kVp, respectively. As a result, these less harmful X-ray shielding materials have the potential to replace lead-based composites, which are highly toxic to human health and have negative environmental consequences.

Preparation and Performance Evaluation of X-ray-Shielding Barium Sulfate Film for Medical Diagnosis Using PET Recycling and Multi-Carrier Principles

The use of disposable containers and packaging materials has increased due to the recent COVID-19 pandemic. Thus, the generation of plastic waste is also increasing, and research on recycling such waste is being actively conducted. In this study, an X-ray-shielding film for medical diagnosis was manufactured by mixing a radiation-shielding material and a plastic waste-based polymer material and its effectiveness was evaluated. The film, which is intended as a fabric for a shielding garment, consists of barium sulfate (BaSO4) shielding nanoparticles embedded in a matrix of polyethylene terephthalate (PET), a commonly available waste plastic material. A particle-dispersing technology, which can improve the ratio between the shielding and matrix materials while maintaining the tensile strength of the film, was studied. Therefore, to increase the content of the barium sulfate (BaSO4) nanoparticles used as the shielding material, this multi-carrier method—under which the particles are dispersed in units of time—was developed to improve the shielding performance. Compared with the effectiveness of lead (Pb) shielding film, the 3 mm barium sulfate film developed in this study satisfies the lead equivalent of 0.150 mmPb when stacked in two layers. Therefore, a shielding film was successfully manufactured by using plastic waste as a polymer resin and barium sulfate, an eco-friendly radiation-shielding material, instead of lead.

Effect of PbO incorporation with different particle size on X-ray attenuation of polystyrene

Lead oxide (PbO) bulk and nanoparticles of two different sizes (A = 78 nm and B = 54 nm) are incorporated separately into the polystyrene matrix at various concentrations (0, 10, 15, 25, and 35 %) using roll mill mixing and compressing molding techniques. The X-ray narrow-spectrum series (N-series / ISO 4037-1) is then used to investigate the radiation attenuation capability of the novel polymer composite PS/PbO, as well as the effect of varying PbO particle sizes on shielding performance. The filler dispersion and chemical elemental analysis of the synthesized composite are investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. To determine the mass attenuation coefficients ?m, samples with various thicknesses of the synthesized composite are examined using a range of X-ray energies, and the experimental data are compared to theoretical values from NIST databases (XCOM and FFAST). The results indicate that either increasing the filler weight percentage or, decreasing the filler particle size, enhanced the attenuation parameters throughout all energies. The composite containing the smallest nanosize of PbO exhibited the maximum radiation shielding efficacy among all combinations and therefore, might be used to develop low-cost and lightweight X-ray shields.

Analysis of Shielding Performance of Radiation-Shielding Materials According to Particle Size and Clustering Effects

In the field of medical radiation shielding, there is an extensive body of research on process technologies for ecofriendly shielding materials that could replace lead. In particular, the particle size and arrangement of the shielding material when blended with a polymer material affect shielding performance. In this study, we observed how the particle size of the shielding material affects shielding performance. Performance and particle structure were observed for every shielding sheet, which were fabricated by mixing microparticles and nanoparticles with a polymer material using the same process. We observed that the smaller the particle size was, the higher both the clustering and shielding effects in the high-energy region. Thus, shielding performance can be improved. In the low-dose region, the effect of particle size on shielding performance was insignificant. Moreover, the shielding sheet in which nanoparticles and microsized particles were mixed showed similar performance to that of the shielding sheet containing only microsized particles. Findings indicate that, when fabricating a shielding sheet using a polymer material, the smaller the particles in the high-energy region are, the better the shielding performance is. However, in the low-energy region, the effect of the particles is insignificant.

Potential of Dual and Multi Energy XRT and CT Analyses on Iron Formations

Dual and multi energy X-ray transmission imaging (DE-/ME-XRT) are powerful tools to acquire quantitative material characteristics of diverse samples without destruction. As those X-ray imaging techniques are based on the projection onto the imaging plane, only two-dimensional data can be obtained. To acquire three-dimensional information and a complete examination on topology and spatial trends of materials, computed tomography (CT) can be used. In combination, these methods may offer a robust non-destructive testing technique for research and industrial applications. For example, the iron ore mining and processing industry requires the ratio of economic iron minerals to siliceous waste material for resource and reserve estimations, and for efficient sorting prior to beneficiation, to avoid equipment destruction due to highly abrasive quartz. While XRT provides information concerning the thickness, areal density and mass fraction of iron and the respective background material, CT may deliver size, distribution and orientation of internal structures. Our study shows that the data provided by XRT and CT is reliable and, together with data processing, can be successfully applied for distinguishing iron oxide rich parts from waste. Furthermore, heavy element bearing minerals such as baryte, uraninite, galena and monazite can be detected.

Quality Assurance of Personal Radiation Shield for Kilovoltage Photon: A Multicentre Experience

Purpose

To optimize the maintenance of radiation shields, this study aims to analyze annual inspection files to assess the integrity of radiation shields and their associated factors with regard to defects in radiation shields in clinical settings.

Methods

A multicenter cross-sectional study was conducted at hospitals in Saudi Arabia. The data from annual inspection files of 1019 clinical lead radiation shields were analyzed. The factors of shield shape, unit where a shield is used, shield thickness, short-term use and number of users were examined. In addition to the inspection file analysis, radiation attenuation measurements were obtained for a subset of shields to compare newly purchased shields with older shields. Statistical analyses were performed using Fisher's exact test and a t-test.

Results

The results show that the highest percentage of failing shields were found in the emergency unit, fluoroscopy unit and operation room with a failure of approximately 7.14%, 5.61%, and 3.98%, respectively, of these shields. Fluoroscopy and operation room units were statistically significantly associated with shield defects. There was no association between shield damage and shape of shield, shield thickness, short-term use or number of users. Radiation attenuation measurements were similar for new and older shields.

Conclusion

As fluoroscopy units and operating rooms have a higher percentage of damaged shields, it is recommended that the shields employed in these units should be regularly inspected more frequently than once a year. The study highlights that the shields' age, transmission measurements that confirm that the correct shields are purchased according to the required kVp, physical appearance, and cleanliness should be recorded in annual inspection files. This study highlights the need for uniform inspection files of radiation shields across hospitals. National and international organizations may apply these findings to develop appropriate recommendations.

Shielding characteristics of nanocomposites for protection against X- and gamma rays in medical applications: effect of particle size, photon energy and nano-particle concentration

In recent decades, nanomaterials have been extensively investigated for many applications. Composites doped with different metal nanoparticles have been suggested as effective shielding materials to replace conventional lead-based materials. The use of concretes as structural and radiation protective material has been influenced by the addition of nanomaterials. Several elements with high atomic number and density, such as lead, bismuth, and tungsten, have the potential to form nanoparticles that offer significant enhancements in the shielding ability of composites. Their performance for a range of particle concentrations, particle sizes, and photon energies have been investigated. This review is an attempt to gather the data published in the literature about the application of nanomaterials in radiation shielding, including the use of polymer composites and concretes for protection against X-rays and gamma radiation.

Designing and Fabricating Nano-structured and Micro-structured Radiation Shields for Protection against CBCT Exposure

Researchers have always been interested in finding new and effective materials for protection against radiation. This experimental study aimed to design and fabricate new types of nano-material and micro-material based shields against the ionizing effect of cone beam computed tomography (CBCT) X-rays. To fabricate a flexible prototype, we added dioctyl phthalate (DOP) oil to emulsion polyvinyl chloride (PVC) powder. The paste was mixed and dispersed. Then, nano- and micro-powders of WO₃ and Bi₂O₃ were added to the paste, with the weight ratio of 20% PVC, 20% DOP, and 60% nano- and micro-metals. Using an ultrasonic mixer, the polymer matrix and metals were mixed and a paste with a thick texture was developed. The resultant paste was poured into glass molds and the molds were then heated in an oven. After cooling, the resultant sheets were selected for further experiments. A CBCT unit and dosimeter were used to evaluate the characterization and X-ray shielding properties of the fabricated prototypes. The half-value layers (HVL) for nano-WO₃, micro-WO₃, nano-Bi₂O_3, and micro-Bi₂O₃ were 0.0390, 0.0524, 0.0351, and 0.0374 cm, respectively. In addition, the linear attenuation coefficient (µ) for these materials were 17.77, 13.20, 19.71, and 18.5 cm⁻¹, respectively. The findings indicate that nano-structured samples are more effective in the attenuation of X-ray energy. The nano-structured WO₃ prototype was nearly 34% more efficient in attenuating radiation compared to the micro-structured WO₃ prototype. This difference in nano- and micro-structured Bi₂O₃ prototypes was 6.5%.

Influence of the size of nano- and microparticles and photon energy on mass attenuation coefficients of bismuth-silicon shields in diagnostic radiology

Recent studies have shown that the particle size of the shielding material and photon energy has significant effects on the efficiency of radiation-shielding materials. The purpose of the current study was to investigate the shielding properties of the bismuth-silicon (Bi-Si) composite containing varying percentages of micro- and nano-sized Bi particles for low-energy X-rays. Radiation composite shields composed of nano- and micro-sized Bi particles in Si-based matrix were constructed. The mass attenuation coefficients of the designed shields were experimentally assessed for diagnostic radiology energy range. In addition, the mass attenuation coefficients of the composite were comprehensively investigated using the MCNPX Monte Carlo (MC) code and XCOM. The X-ray attenuation for two different micro-sized Bi composites of radii of 50 µm and 0.50 µm showed enhancement in the range of 37-79% and 5-24%, respectively, for mono-energy photons (60-150 keV). Furthermore, the experimental and MC results indicated that nano-structured composites had higher photon attenuation properties (approximately 11-18%) than those of micro-sized samples for poly-energy X-ray photons. The amount of radiation attenuation for lower energies was more than that of higher energies. Thus, it was found that the shielding properties of composites were considerably strengthened by adding Bi nano-particles for lower energy photons.

Evaluation of new transparent tungsten containing nanocomposites for radiation protection screens

Evaluation of the new lead-free optically transparent nanocomposites is provided in this paper along with the introduction to their fabrication technologies and the results of investigation of their X-ray attenuating and optical properties before and after their exposure to high doses. These materials might be considered for the construction of X-ray protective screens that are used to protect medical personnel against scattered X rays during close-to patient operations. Rough selection of possible composites was performed according to X-ray attenuation modelling results. Experimental nanocomposites were prepared dissolving tungstates in different solvents or embedding tungsten structures into polymer matrix. It was found that the lead equivalent thickness of fabricated experimental samples varied from 0.15 to 0.75 mmPb and was higher for samples, containing polyanions of phosphotungstic acid. Transparency of the experimental samples to visible light varied from 20 to 60 % and was slightly increasing with irradiation dose due to radiation-induced processes in polymers.

Bismuth sulfide nanoflowers for detection of X-rays in the mammographic energy range

The increased use of diagnostic x-rays, especially in the field of medical radiology, has necessitated a significant demand for high resolution, real-time radiation detectors. In this regard, the photoresponse of bismuth sulfide (Bi2S3), an n-type semiconducting metal chalcogenide, to low energy x-rays has been investigated in this study. In recent years, several types of nanomaterials of Bi2S3 have been widely studied for optoelectronic and thermoelectric applications. However, photoresponse of Bi2S3 nanomaterials for dosimetric applications has not yet been reported. The photosensitivity of Bi2S3 with nanoscale "flower-like" structures was characterized under x-ray tube-potentials typically used in mammographic procedures. Both dark current and photocurrent were measured under varying x-ray doses, field sizes, and bias voltages for each of the tube potentials - 20, 23, 26 and 30 kV. Results show that the Bi2S3 nanoflowers instantaneously responded to even minor changes in the dose delivered. The photoresponse was found to be relatively high (few nA) at bias voltage as low as +1 V, and fairly repeatable for both short and long exposures to mammographic x-rays with minimal or no loss in sensitivity. The overall dose-sensitivity of the Bi2S3 nanoflowers was found to be similar to that of a micro-ionization chamber.

Characterisation of micro-sized and nano-sized tungsten oxide-epoxy composites for radiation shielding of diagnostic X-rays

Characteristics of X-ray transmissions were investigated for epoxy composites filled with 2-10 vol% WO3 loadings using synchrotron X-ray absorption spectroscopy (XAS) at 10-40 keV. The results obtained were used to determine the equivalent X-ray energies for the operating X-ray tube voltages of mammography and radiology machines. The results confirmed the superior attenuation ability of nano-sized WO3-epoxy composites in the energy range of 10-25 keV when compared to their micro-sized counterparts. However, at higher synchrotron radiation energies (i.e., 30-40 keV), the X-ray transmission characteristics were similar with no apparent size effect for both nano-sized and micro-sized WO3-epoxy composites. The equivalent X-ray energies for the operating X-ray tube voltages of the mammography unit (25-49 kV) were in the range of 15-25 keV. Similarly, for a radiology unit operating at 40-60 kV, the equivalent energy range was 25-40 keV, and for operating voltages greater than 60 kV (i.e., 70-100 kV), the equivalent energy was in excess of 40 keV. The mechanical properties of epoxy composites increased initially with an increase in the filler loading but a further increase in the WO3 loading resulted in deterioration of flexural strength, modulus and hardness.

Characteristics of X-ray attenuation in electrospun bismuth oxide/polylactic acid nanofibre mats

The characteristics of the X-ray attenuation in electrospun nano(n)- and micro(m)-Bi2O3/polylactic acid (PLA) nanofibre mats with different Bi2O3 loadings were compared as a function of energy using mammography (i.e. tube voltages of 22-49 kV) and X-ray absorption spectroscopy (XAS) (7-20 keV). Results indicate that X-ray attenuation by electrospun n-Bi2O3/PLA nanofibre mats is distinctly higher than that of m-Bi2O3/PLA nanofibre mats at all energies investigated. In addition, with increasing filler loading (n-Bi2O3 or m-Bi2O3), the porosity of the nanofibre mats decreased, thus increasing the X-ray attenuation, except for the sample containing 38 wt% Bi2O3 (the highest loading in the present study). The latter showed higher porosity, with some beads formed, thus resulting in a sudden decrease in the X-ray attenuation.

Polymer-composite materials for radiation protection

Unwanted exposures to high-energy or ionizing radiation can be hazardous to health. Prolonged or accumulated radiation dosage from either particle-emissions such as alpha/beta, proton, electron, neutron emissions, or high-energy electromagnetic waves such as X-rays/γ rays, may result in carcinogenesis, cell mutations, organ failure, etc. To avoid occupational hazards from these kinds of exposures, researchers have traditionally used heavy metals or their composites to attenuate the radiation. However, protective gear made of heavy metals are not only cumbersome but also are capable of producing more penetrative secondary radiations which requires additional shielding, increasing the cost and the weight factor. Consequently, significant research efforts have been focused toward designing efficient, lightweight, cost-effective, and flexible shielding materials for protection against radiation encountered in various industries (aerospace, hospitals, and nuclear reactors). In this regard, polymer composites have become attractive candidates for developing materials that can be designed to effectively attenuate photon or particle radiation. In this paper, we review the state-of-the-art of polymer composites reinforced with micro/nanomaterials, for their use as radiation shields.