High Atomic Number Elements Research Articles

Development of novel multifunctional phase change microcapsules for improving thermal comfort and radiation properties

Microencapsulated phase change materials (MPCMs) have gained widespread application in energy-efficient buildings, aiming to improve thermal comfort and reduce energy consumption. To enhance the engineering feasibility of MPCMs, researchers are now focusing on developing MPCMs with multifunctional properties, beyond single thermal storage functionality. In this study, we proposed a novel and straightforward approach to fabricate multifunctional MPCMs with BaCO3 as shell and a core composed of binary phase change materials (PCMs) and lipophilic-modified graphite (MG) via self-assembly method. The incorporation of BaCO3 shell provides MPCMs with additional resistance to ionizing radiation pollution due to the high atomic number element Ba. Additionally, the incorporation of MG into PCMs enhances its temperature sensitivity. The thermal analysis indicates that the binary PCMs’ composition in MPCMs results in two phase transition temperatures at 3.3 °C and 26.4 °C, making them capable of thermal storage in line with comfortable residential temperatures across different seasons. Furthermore, MPCMs were introduced into cement paste (CPM) and used to construct cement chambers. Adding 10 wt% MPCMs in the CPM chambers placed outdoors in Wuhan (from June 7th to June 9th) led to a 23.8 % decrease in temperature fluctuations compared to the reference sample. Radiation shielding results indicated that the linear attenuation coefficient (μ) of CPM increased by 58.7 %, due to enhanced incoherent scattering and photoelectric effects between high atomic number elements and photons. Additionally, XCOM simulations predicted a strong correlation between MPCM content and μ values, with particularly high accuracy at low photon energies. Overall, the multifunctional MPCMs developed in this study not only offers a new route for reducing residential energy consumption and shielding ionizing pollution, but also broadens the applicability of traditional PCMs in the building and other fields.

High-sensitivity and spatial resolution benchtop cone beam XFCT imaging system with pixelated photon counting detectors using enhanced multipixel events correction method

Objective.High atomic number element nanoparticles have shown potential in tumor diagnosis and therapy. X-ray fluorescence computed tomography (XFCT) technology enables quantitative imaging of high atomic number elements by specifically detecting characteristic x-ray signals. The potential for further biomedical applications of XFCT depends on balancing sensitivity, spatial resolution, and imaging speed in existing XFCT imaging systems.Approach.In this study, we utilized a high-energy resolution pixelated photon-counting detector for XFCT imaging. We tackled degradation caused by multi-pixel events in the photon-counting detector through energy and interaction position corrections. Sensitivity and spatial resolution imaging experiments were conducted using PMMA phantoms to validate the effectiveness of the multi-pixel events correction algorithm.Main results.After correction, the system's sensitivity and spatial resolution have both improved. Furthermore, XFCT/CBCT dual-modality imaging of gadolinium nanoparticles within mice subcutaneous tumor was successfully achieved.Significance.These results demonstrate the preclinical research application potential of the XFCT/CBCT dual-modality imaging system in high atomic number nanoparticle-based tumor diagnosis and therapy.

Comparison of photon interaction coefficients for tumor compositions and healthy tissues simulated by Monte Carlo

This study compares interaction coefficients of photons (namely, mass attenuation, energy absorption and energy transfer coefficients) for some tumor tissues with simlar healthy tissues. Monte Carlo calculations were performed for adenoidcystic carcinoma, melanoma, rectal adenocarcinoma, sarcoma and squamous cell lung carcinoma. The simulation model involved a monoenergetic point source producing a pencil beam. Depending on the parameter under study, average flux, energy flux, or dose deposition from photons that travels in an absorber were scored in the range of 10 keV–20 MeV energy using MCNP6.1. The same model was used to compute the interaction coefficients of health tissues (namely, gastrointestinal tract-small intestine wall, lungs-parenchyma, salivary glands, skin, soft tissue (female+male)) for comparison purposes. The results showed that, depending on the contents of the tumor samples, photon interaction coefficients of a tumor may differ from those of a similar healthy tissue. This behavior was distinct, especially for energies up to 100 keV, and was attributed to the presence of relatively higher atomic number elements in the absorber.

Enhancing X-Ray Sensitization with Multifunctional Nanoparticles.

In the progression of X-ray-based radiotherapy for the treatment of cancer, the incorporation of nanoparticles (NPs) has a transformative impact. This study investigates the potential of NPs, particularly those comprised of high atomic number elements, as radiosensitizers. This aims to optimize localized radiation doses within tumors, thereby maximizing therapeutic efficacy while preserving surrounding tissues. The multifaceted applications of NPs in radiotherapy encompass collaborative interactions with chemotherapeutic, immunotherapeutic, and targeted pharmaceuticals, along with contributions to photodynamic/photothermal therapy, imaging enhancement, and the integration of artificial intelligence technology. Despite promising preclinical outcomes, the paper acknowledges challenges in the clinical translation of these findings. The conclusion maintains an optimistic stance, emphasizing ongoing trials and technological advancements that bolster personalized treatment approaches. The paper advocates for continuous research and clinical validation, envisioning the integration of NPs as a revolutionary paradigm in cancer therapy, ultimately enhancing patient outcomes.

Abstract 2870: Analysis of cancer cells response to radiotherapy activated NBTXR3 nanoparticles

Abstract In 2011, NBTXR3 emerged as the first-in-class radioenhancer used in clinical practice for treating patients with locally advanced soft tissue sarcoma (LA-STS). NBTXR3 became the first radioenhancer to receive CE mark approval after successfully completing a phase II/III clinical study for LA-STS with a doubling of the pCR rate in the NBTXR3 arm compared with the control arm. NBTXR3 nanoparticles consist of a functionalized core of hafnium oxide, a high atomic number element, specifically designed to amplify the effects of radiotherapy (RT) within cells without additional side effects on healthy tissues. Leveraging this physical mechanism, RT-activated NBTXR3 (NBTXR3+RT) has demonstrated superior efficacy in destroying tumor cells and controlling tumor growth in numerous preclinical models and in human, surpassing the effects of RT alone, while maintaining a favorable safety profile. Preclinical studies have revealed that the benefits of NBTXR3 extend beyond mere radioenhancement and improved cancer cell destruction. Specifically, NBTXR3 has been reported to possess immunomodulatory properties through 1) improved induction of DNA damage, leading to better activation of the cGAS-STING pathway, 2) promotion of immunogenic cell death, 3) enhancement of immunopeptidome presentation, 4) generation of an antitumor immune response leading to the production of an abscopal effect mediated by CD8+ cytotoxic lymphocytes. Notably, a series of recent studies using a two-tumor mouse model of anti-PD1-resistant lung cancer that the addition of NBTXR3 significantly improved the efficacy of various treatment regimens (RT+anti-PD1 and combinations with other check-point inhibitors) in terms of tumor growth, abscopal effect, and survival. It has been demonstrated that same benefits can be achieved when NBTXR3 was combined with proton therapy. Moreover, all these studies (X-ray and proton) reported a robust activation of the antitumor immune response, restoration of the effectiveness of anti-PD1 therapy, and the induction of memory response in cured mice. However, our understanding of the biological events leading to these effects remains limited. To address this question, we conducted a series of in vitro studies that employed cytometry, microscopy, and RNA sequencing on various cancer models, both human and murine. We reported that NBTXR3 nanoparticles primarily accumulate within lysosomes following their uptake by tumor cells, leading to the activation of genes associated with the biogenesis, structure, and contents of these organelles. Upon activation by RT, NBTXR3 within lysosomes induces lysosomal membrane permeabilization (LMP), resulting in an increase in lipid peroxidation, inducing regulation of fatty acid oxidation genes, and impacting mitochondrial genes expression, such as respirasome. These findings provide a deeper insight into the early biological effects of NBTXR3+RT in comparison to RT alone. Citation Format: Jordan Da Silva, Celia Bienassis, Sebastien Paris. Analysis of cancer cells response to radiotherapy activated NBTXR3 nanoparticles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2870.

Abstract 2973: Analysis of NBTXR3 nanoparticles recapture after release by dying cells

Abstract In 2011, NBTXR3 emerged as the pioneering radioenhancer used in clinical practice to treat patients with locally advanced soft tissue sarcoma (LA-STS). Following the successful completion of a phase II/III clinical study for LA-STS, with a doubling of the pCR rate in the NBTXR3 arm compared with the control arm. NBTXR3 became the first radioenhancer to receive CE mark approval. NBTXR3 nanoparticles are composed of a functionalized core made of hafnium oxide, a high atomic number element. They were designed to enhance the effects of radiotherapy (RT) within cells without causing additional side effects on healthy tissues. Exploiting this physical mechanism, radiation-activated NBTXR3 (NBTXR3+RT) has exhibited superior efficacy in eradicating tumor cells and managing tumor growth in various preclinical models and in human studies. It surpasses the effects of RT alone while maintaining a favorable safety profile. Recent preclinical investigations have uncovered that the advantages of NBTXR3 go beyond mere radioenhancement and improved cancer cell destruction. Notably, NBTXR3 has been reported to possess immunomodulatory properties through several mechanisms, including 1) improved induction of DNA damage, leading to enhanced activation of the cGAS-STING pathway, 2) promotion of immunogenic cell death, 3) enhancement of immunopeptidome presentation, 4) generation of an antitumor immune response that results in the production of an abscopal effect mediated by CD8+ cytotoxic lymphocytes. Significantly, a series of recent studies using a two-tumor mouse model of anti-PD1-resistant lung cancer demonstrated that the addition of NBTXR3 significantly improved the efficacy of various treatment regimens (combinations of RT plus anti-PD1 and other checkpoint inhibitors) in terms of tumor growth, abscopal effect, and overall survival. Furthermore, similar benefits can be achieved when NBTXR3 is combined with proton therapy (PBT). Moreover, all these studies (both X-ray and PBT) reported a robust activation of the antitumor immune response, the restoration of the effectiveness of anti-PD1 therapy, and the induction of a memory response in cured mice. But our knowledge of the underlying biological processes that lead to these effects remains rather limited. For example, no information is available about the fate of these nanoparticles once they are injected into a tumor or when they are released by dying cancer cells. To gain a better understanding of these issues, we conducted a series of in vitro and in vivo experiments. We demonstrate that the endocytosis occurs similarly both in vivo and in vitro, at the level of tumor cells. Furthermore, we demonstrate in vitro that nanoparticles taken up by these tumor cells and subsequently released upon their death can be reinternalized by other tumor cells, thus facilitating their destruction by RT. These initial findings provide a deeper insight into the behavior of NBTXR3. Citation Format: Jordan Da silva, Célia Bienassis, Sebastien Paris. Analysis of NBTXR3 nanoparticles recapture after release by dying cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2973.

Soft glass optical fiber characterization with X-ray computed microtomography

The high loss due to the presence of strong phonon resonances makes silica fibers unfit for applications in the mid-infrared spectral range. This has led to the development of specialty optical fibers, based on novel materials and manufacturing techniques. In some cases, the characterization of these new fibers by means of standard techniques may be challenging. Fiber manufacturers would strongly benefit from a tool, which is capable of checking the geometrical and optical properties of fibers (either after fiber drawing, or even in real-time, during the drawing process). Here, we propose and demonstrate that absorption contrast X-ray computed microtomography is a non-destructive technique, capable of characterizing both geometrical and optical properties of specialty optical fibers. We experimentally verified that the tomographic intensity profile in the fiber core has the same shape as the refractive index profile, which we determined via energy-dispersed X-ray spectroscopy. We tested step- and graded-index soft glass fibers, both purchased and made in-house. Owing to the presence of high atomic number elements, which provide higher X-ray cross-section, soft glasses were more suitable than silica for their characterization via X-ray computed microtomography.

Seeing in the dark: Challenges in the interpretation of x‐ray fluorescence element distribution maps associated with black paints

AbstractDuring the conservation of easel paintings, black draperies or dark backgrounds often prove problematic to treat and understand in terms of condition. Despite most black pigments in Old Master paintings not intrinsically containing high atomic number elements, the investigation of black paints is one of the National Gallery's major uses and most helpful applications of x‐ray fluorescence (XRF) scanning. As a visual tool, XRF element distribution maps of black paints are useful for assessing the extent of overpainting or condition of any surviving original paint beneath, and for revealing the original modelling. However, interpreting the XRF element maps can be challenging. It is important to consider not only the primary compositions of black or dark pigments, but to have an understanding of other possible associated materials and more broadly of historical painting techniques, artists' practices and the paint stratigraphy. Through a series of case studies, this paper demonstrates how a detailed knowledge of historic painting materials and techniques, based on study of documentary sources and archives of materials‐based evidence from the analysis of paint cross‐sections—both from the paintings being studied and related works—aids and enriches interpretation of XRF element maps of black paints. While samples are invaluable in understanding exactly how—and with what materials—such regions were painted, they are not always representative and scanning XRF may be of complementary benefit in providing a more holistic view of pigment distribution. The examples presented range from the fifteenth to the seventeenth century from both Northern Europe and Italy.

Non-destructive 3D characterization of the blood vessel wall microstructure in different species and blood vessel types using contrast-enhanced microCT and comparison with synthetic vascular grafts

To improve the current treatment for vascular diseases, such as vascular grafts, intravascular stents, and balloon angioplasty intervention, the evaluation of the native blood vessel microstructure in full 3D could be beneficial. For this purpose, we used contrast-enhanced X-ray microfocus computed tomography (CECT): a combination of X-ray microfocus computed tomography (microCT) and contrast-enhancing staining agents (CESAs) containing high atomic number elements. In this work, we performed a comparative study based on staining time and contrast-enhancement of 2 CESAs: Monolacunary and 1:2 Hafnium-substituted Wells-Dawson polyoxometalate (Mono-WD POM and Hf-WD POM, respectively) for imaging of the porcine aorta. After showing the advantages of Hf-WD POM in terms of contrast enhancement, we expanded our imaging to other species (rat, porcine, and human) and other types of blood vessels (porcine aorta, femoral artery, and vena cava), clearly indicating microstructural differences between different types of blood vessels and different species. We then showed the possibility to extract useful 3D quantitative information from the rat and porcine aortic wall, potentially to be used for computational modeling or for future design optimization of graft materials. Finally, a structural comparison with existing synthetic vascular grafts was made. This information will allow to better understand the in vivo functioning of native blood vessels and to improve the current disease treatments. STATEMENT OF SIGNIFICANCE: Synthetic vascular grafts, used as treatment for some cardiovascular diseases, still often fail clinically, potentially because of a mismatch in mechanical behaviour between the native blood vessel and the graft. To better understand the causes of this mismatch, we studied the full 3D microstructure of blood vessels. For this, we identified Hafnium-substituted Wells-Dawson polyoxometalate as contrast-enhancing staining agent to perform contrast-enhanced X-ray microfocus computed tomography. This technique allowed to show important differences in the microstructure of different types of blood vessels and in different species, as well as with that of synthetic grafts. This information can lead to a better understanding of the functioning of blood vessels and will allow to improve current disease treatments, such as vascular grafts.

New Contrast Media for K-Edge Imaging With Photon-Counting Detector CT.

The recent technological developments in photon-counting detector computed tomography (PCD-CT) and the introduction of the first commercially available clinical PCD-CT unit open up new exciting opportunities for contrast media research. With PCD-CT, the efficacy of available iodine-based contrast media improves, allowing for a reduction of iodine dosage or, on the other hand, an improvement of image quality in low contrast indications. Virtual monoenergetic image reconstructions are routinely available and enable the virtual monoenergetic image energy to be adapted to the diagnostic task.A key property of PCD-CT is the ability of spectral separation in combination with improved material decomposition. Thus, the discrimination of contrast media from intrinsic or pathological tissues and the discrimination of 2 or more contrasting elements that characterize different tissues are attractive fields for contrast media research. For these approaches, K-edge imaging in combination with high atomic number elements such as the lanthanides, tungsten, tantalum, or bismuth plays a central role.The purpose of this article is to present an overview of innovative contrast media concepts that use high atomic number elements. The emphasis is on improving contrast enhancement for cardiovascular plaque imaging, stent visualization, and exploring new approaches using 2 contrasting elements. Along with the published research, new experimental findings with a contrast medium that incorporates tungsten are included.Both the literature review and the new experimental data demonstrate the great potential and feasibility for new contrast media to significantly increase diagnostic performance and to enable new clinical fields and indications in combination with PCD-CT.

Preparation of alginate coated Pt nanoparticle for radiosensitization of breast cancer tumor

Noble metals as high atomic number elements can localize X-ray radiation within tumor cells by exploiting different mechanisms. Here, alginate (Alg)-coated platinum nanoparticles (Pt@Alg) were synthesized, characterized, and implemented as a radiosensitizer to enhance X-ray therapeutic efficacy in breast cancer in vitro and in vivo. Alg not only improves the biocompatibility of the radioenhancer, but also stabilizes the nanoparticles. Pt@Alg was studied by different characterization methods including DLS, STEM, Fe-SEM, XRD, XPS, FT-IR and UV–Vis spectrophotometry. The nanosystem provided a higher level of intracellular ROS in malignant cells and enhanced cancer cell death under X-Ray irradiation. Clonogenic assay also demonstrated the radiosensitizing properties of the nanosystem, in vitro. In vivo result show tumor growth restraining properties of the nanosystem when it was administrated along with X-Ray irradiation. Histopathology results confirmed the impact of nanosystem and X-ray co-treatment, as well. Altogether, the importance of radiosensitizers for improving radiotherapy outcomes was highlighted.

Elemental Variability of PM2.5 Aerosols in Historical and Modern Areas of Jeddah, Saudi Arabia

Air particulate matter with a diameter of 2.5 µm (PM2.5) were assembled for a whole year from the historical Jeddah district. Additional PM2.5 aerosols were collected during the autumn and winter seasons from another newly constructed district in Jeddah city (Alnaeem). The annual concentration of the total mass of the PM2.5 aerosols from the historical Jeddah site was found to be 43 ± 6 µg/m3. In addition, the average of the total mass concentration at the Alnaeem site was 61 ± 14 µg/m3. These values were greater than the annual mass concentration of the air quality standards of the European Commission (25 µg/m3) and the World Health Organization (10 µg/m3). The elemental analysis of the collected fine atmospheric aerosols was achieved by energy dispersive X-ray fluorescence (EDXRF) with three secondary targets (CaF2, Ge, and Mo). Quantitative elemental analyses of twenty-two (22) elements were achieved starting from the low atomic number element (Na) up to the high atomic number element (Pb). Although the historical Jeddah site is not well organized, the elemental concentrations and total mass concentrations were lower than those of the other site. The statistical analyses including enrichment factors, correlation analysis, and the principal component analysis revealed more information about the source identification of the PM2.5 aerosols collected from both locations. It was recognized that the elements Al, Si, K, Ca, Ti, Mn, Fe, Rb, and Sr originated from a natural source. On the other hand, the elements Ta, Br, Pb, Sc, Ni, Cu, Zn, and S originated from anthropogenic sources. Finally, the elements Na, Cl, and Br came mainly from the sea spray source.

Preparation of multifunctional phase change microcapsules for thermal energy storage and shielding against ionizing radiation

A novel type of multifunctional microencapsulated phase change materials (MPCMs) with BaCO3 as shell and binary phase change materials (PCMs) as core was prepared based on self-assembly method. In addition to their original thermal storage properties, MPCMs are endowed with the ability to shield against ionizing radiation by the BaCO3 shell containing high atomic number element Ba2+. Thermal analysis indicated that due to the composition of binary PCMs, MPCMs had phase transition points of 5.54 °C and 32.6 °C, which enabled MPCMs with thermal storage function in wide temperature ranges. Furthermore, the cement paste containing different replacement ratio of MPCMs was exposed to X-ray radiation. The results showed that with the addition of MPCMs, the linear attenuation coefficient of cement paste had a general increase over the photon energy range of 0.05–0.15 MeV, especially at the lower photon energy. The multifunctional MPCMs developed in this study provides applicability for traditional thermal storage materials in building and other fields.

Enhancing anti-tumor effect of ultrasensitive bimetallic RuCu nanoparticles as radiosensitizers with dual enzyme-like activities

Radiotherapy (RT), through the generation of reactive oxygen species (ROS) and DNA damage to tumor cells caused by high-energy irradiation, has been a widely applied cancer treatment strategy in clinic. However, the therapeutic effect of traditional RT is restricted by the insufficient radiation energy deposition and the side effects on normal tissues. Recently, multifunctional nano-formulations and synergistic therapy has been developed as attractive strategies for used to enhancing the efficacy and safety of RT. Herein, we show that a bimetallic nanozyme (copper-modified ruthenium nanoparticles, RuCu NPs), containing the high atomic number (Z) element Ru as a novel radiosensitizer, offers an ideal solution to RT sensitization, with ultrasensitive peroxidase (POD)-like activity and catalase (CAT)-like activity. Density functional theory (DFT) calculations also clarified the optimal POD-like catalytic ratio of RuCu NPs and further revealed the mechanism of its supper catalytic activity. Under X-ray exposure, RuCu NPs coated with poly(ethylene glycol) (PEG) exhibited simultaneously improved the ROS production and relieved tumor hypoxia in the acid tumor microenvironment (TME), and demonstrated remarkable therapeutic efficacy in the MDA-MB-231 breast cancer model. Our results provide a proof-of-concept for a RT sensitization strategy, which combine the intrinsic nature of high-Z element and the advantages of nanozymes to overcome the tricky drawbacks existed in radiotherapy, and further open a new direction of exploring novel nanozyme-based strategies for tumor catalytic therapy and synergistic radiotherapy.

On-Demand Generation of Peroxynitrite from an Integrated Two-Dimensional System for Enhanced Tumor Therapy.

Nanosystem-mediated tumor radiosensitization strategy combining the features of X-ray with infinite penetration depth and high atomic number elements shows considerable application potential in clinical cancer therapy. However, it is difficult to achieve satisfactory anticancer efficacy using clinical radiotherapy for the majority of solid tumors due to the restrictions brought about by the tumor hypoxia, insufficient DNA damage, and rapid DNA repair during and after treatment. Inspired by the complementary advantages of nitric oxide (NO) and X-ray-induced photodynamic therapy, we herein report a two-dimensional nanoplatform by the integration of the NO donor-modified LiYF4:Ce scintillator and graphitic carbon nitride nanosheets for on-demand generation of highly cytotoxic peroxynitrite (ONOO-). By simply adjusting the Ce3+ doping content, the obtained nanoscintillator can realize high radioluminescence, activating photosensitive materials to simultaneously generate NO and superoxide radical for the formation of ONOO- in the tumor. Obtained ONOO- effectively amplifies therapeutic efficacy of radiotherapy by directly inducing mitochondrial and DNA damage, overcoming hypoxia-associated radiation resistance. The level of glutamine synthetase (GS) is downregulated by ONOO-, and the inhibition of GS delays DNA damage repair, further enhancing radiosensitivity. This work establishes a combinatorial strategy of ONOO- to overcome the major limitations of radiotherapy and provides insightful guidance to clinical radiotherapy.

Effect of the new photoatomic data library EPDL2017 to mass attenuation coefficient calculation of materials used in the nuclear medicine facilities using EpiXS software

The accuracy of the photoatomic cross-section data is of great importance in the field of radiation protection, particularly in the characterization of radiation shielding materials. With the release of the latest and probably the most accurate photoatomic data library, EPDL2017, the need to re-evaluate all the existing and already established mass attenuation coefficients (MACs) of all radiation shielding materials arises. The MACs of several polymers, alloy-based, glasses, and building materials used in a nuclear medicine facility were investigated using the EPDL2017 library embedded in EpiXS software and were compared to MACs available in the literature. The relative differences between MACEpiXS and MACXCOM were negligible, ranging from 0.02% to 0.36% for most materials. However, for material like a glass comprising of elements Te and La evaluated near their corresponding K-edge energies, the relative differences in MACs increased up to 1.46%. On the other hand, a comparison with MACs calculated based on EPDL97 (a predecessor of EPDL2017) revealed as much as a 6.61% difference. Also, it would seem that the changes in MACs were more evident in the materials composed of high atomic number elements evaluated at x-ray energies compared to materials composed of low atomic number elements evaluated at gamma-ray energies.

Photon Interaction Coefficients for the Colorectal Cancer Tissue.

The application of radiotherapy to the treatment of cancer requires the knowledge of photon interaction coefficients such as mass attenuation (μm) and mass energy-absorption coefficients (μen/ρ). Although these coefficients have been determined for different tissues, it is lacking for the colorectal cancer (CRC) tissue in the literature. This study determines the μm and μen/ρ for the CRC tissue within the radiotherapy energy range. The CRC tissue from autopsy patients was freeze-dried, grounded into a fine powder, and made into pellets of 1 cm thickness. The elements detected in the CRC tissue using Rutherford backscattering spectrometry were used in XCOM to determine the theoretical values of μm and μen/ρ. The CRC tissue was again exposed to X-rays of energies of 6 and 15MV, respectively, to determine its experimental values of μm and μen/ρ. Elements detected included carbon, oxygen and nitrogen making up 96.67%, high atomic number and trace elements making up the remaining 3.33% fraction of the CRC tissue. The theoretical and experimental μm and μen/ρ values showed a good agreement of about 2% difference between them. These values can be used to simulate the CRC tissue with respect to μm and μen/ρ.

Multi-Energy Gamma-Ray Attenuations for Non-Destructive Detection of Hazardous Materials

We present a non-destructive method (NDM) to identify minute quantities of high atomic number (Z) elements in containers such as passenger baggage, goods carrying transport trucks, and environmental samples. This method relies on the fact that photon attenuation varies with its energy and properties of the absorbing medium. Low-energy gamma-ray intensity loss is sensitive to the atomic number of the absorbing medium, while that of higher-energies vary with the density of the medium. To verify the usefulness of this feature for NDM, we carried out simultaneous measurements of intensities of multiple gamma rays of energies 81 to 1408 keV emitted by sources 133Ba (half-life = 10.55 y) and 152Eu (half-life = 13.52 y). By this arrangement, we could detect minute quantities of lead and copper in a bulk medium from energy dependent gamma-ray attenuations. It seems that this method will offer a reliable, low-cost, low-maintenance alternative to X-ray or accelerator-based techniques for the NDM of high-Z materials such as mercury, lead, uranium, and transuranic elements etc.

Determination of the uranium elemental concentration in molten salt fuel using laser-induced breakdown spectroscopy with partial least squares-artificial neural network hybrid models

Accurate uranium (U) composition analysis of the molten salt nuclear fuel mixture is a necessary step in nuclear fuel quality control. Laser-induced breakdown spectroscopy (LIBS) is an optical emission spectrometry technique for elemental composition. The non-linear phenomena in LIBS signal are the drawback of this technique, especially for high atomic number (Z) element in a complex matrix. To overcome this limitation, a hybrid chemometrics model of the partial least squares-artificial neural network (PLS-ANN) was used to quantify the U composition in the salt fuel mixture of Molten salt breeder reactor. This work shows the optimisation of several parameters, viz., spectra pre-treatment procedure, factor number of PLS for ANN input, number of hidden neurons and layers in ANN, activation function, and number of ANN iterations. The collective advantages of data dimension reduction from PLS and the nonlinear processing ability from ANN, improved the accuracy of LIBS quantitative analysis for U from ≈7% using simple PLS to ≈4% precision using a hybrid model.

OXIRIS project: Development of a new XRF device for the simultaneous detection and treatment of cancer

AbstractA novel and suitable energy‐dispersive X‐ray fluorescent (EDXRF) device, currently at the prototype stage, the Project OXIRIS (Orthovoltage X‐Ray–Induced Radiation System), is presented for the simultaneous detection and treatment of cancer diseases. Monte Carlo simulation and experimental results of EDXRF signals from a small deep artificial tumor consisting of a solution of gold nanoparticles bio‐targeted and immersed in a tissue‐bioequivalent matrix are presented and compared. Briefly, the device consists of a dynamic orthovoltage X‐ray fluence concentration coupled to confocal with an EDXRF system along with a sample holder for 3D scanning; all integrated and controlled by a dedicated software capable of controlling the whole operation functionalities: the X‐ray source, the rotating arm, the sample holder, and the detection system. The software also includes dedicated subroutines for X‐ray fluorescent spectra processing to correlate K‐lines signal at each acquisition position with the corresponding high atomic number elements' concentration to produce a 3D distribution according to the user‐defined grid. The confocal configuration ensures that the detected signal comes exclusively from the excited volume as defined by the bulk of the focal spot. Hence, the 3D image is achieved by scanning the sample holder through the movement of the sample‐carrier stretcher moved by step motors in the 3 coordinated axes. The feasibility of the proposed methodology and the design of the prototype have been successfully demonstrated experimentally, targeting gold nanoparticles in water‐equivalent phantoms.