Search Results (48)

In this study, a two-dimensional gamma-ray source localization system using a mesh array of plastic scintillating fibers and an artificial neural network is presented. The system covers a 200 cm by 100 cm area using SCSF-78 multi-cladded fibers. A novel U-shaped fiber topology connects both fiber ends to one side, requiring only two data-acquisition systems. Silicon photomultiplier arrays measure fast time-of-flight under optimized operating conditions to maximize signal yield. An independent artificial neural network model map measured time-of-flight values to spatial coordinates, compensating for systematic non idealities. Performance was validated using a Cesium-137 source at 20 random test positions. The artificial neural network method achieved a mean full-scale error of 4.6%. This demonstrated a 79.34% accuracy improvement over direct theoretical calculation, which had a mean full-scale error of 22.5%. The system showed consistent performance, achieving a two-dimensional standard deviation of 0.492 cm during repeatability assessment. This methodology provides a practical, efficient approach to two-dimensional radiation source localization suitable for real time monitoring and contamination mapping. Full article

Background/Objectives: In a previous study, we observed significantly prolonged hepatic and pulmonary first-pass transit times (TTs) for ^99mTc-pertechnetate absorbed through the colorectal mucosa during per-rectal portal scintigraphy (PRPS). This decrease in radiotracer flow velocity was not seen when ^99mTc-pertechnetate was administered into the spleen during trans-splenic portal scintigraphy or injected intravenously in radionuclide angiocardiography. We hypothesized that ^99mTc-pertechnetate, an artificial compound, is recognized during colorectal absorption as a potentially hazardous chemical (PHC), with its hepatic and pulmonary slowdown aiding elimination. A similar sudden decrease in portal flow occurs during early metastasis of colorectal cancer (CRC), as shown by a pathological rise in the hepatic perfusion index. We aimed to study the hepatic and pulmonary vasoactive responses triggered by PHCs after they pass through the gut mucosa and evaluate the potential activation of this mechanism in early CRC metastasis. Methods: We measured transit times to determine whether hepatic and pulmonary vasoconstriction occur in response to radiotracers administered at different sites. We performed PRPS with in vivo ^99mTc-labelled RBC to evaluate the liver transit time (LTT) and right heart to liver circulation time (RHLT). Liver angioscintigraphy (LAS) was used to assess RHLT following the intravenous injection of ^99mTc-pertechnetate and ^99mTc-HDP (hydroxyethylene-diphosphate). Lower rectum transmucosal dynamic scintigraphy (LR-TMDS) was conducted to measure RHLT of ^99mTc-pertechnetate delivered into the lower rectum submucosa. LAS was performed to assess LTT for ^99mTc-HDP intravenously injected and delivered to the gut mucosa via arterial flow. Results: In healthy volunteers, PRPS showed notably increased LTT, ranging from 23.5 to 25.5 s, and RHLT (between 39.5 and 42.5 s) for in vivo ^99mTc-labelled RBC. Significantly lower RHLT values ranging from 9 to 13.5 were observed for ^99mTc-pertechnetate and ^99mTc-HDP administered intravenously during LAS, as well as for ^99mTc-pertechnetate at LR–TMDS (between 12 and 15 s). The LTT assessed at LAS for ^99mTc-HDP ranged from 22 to 27 s. Conclusions: An intense vasoconstriction occurs in the liver and lungs in response to substances recognized by the body as PHCs when they pass through the gut mucosa, aiding their elimination. Full article

Targeted radionuclide therapy (TRT) utilizes radiopharmaceuticals to deliver radiation directly to cancer cells while sparing healthy tissues. Beyond the absorbed dose of ablative radiation, TRT induces non-targeted effects (NTEs) that significantly enhance its therapeutic efficacy. These effects include radiation-induced bystander effects (RIBEs), abscopal effects (AEs), radiation-induced genomic instability (RIGI), and adaptive responses, which collectively influence the behavior of cancer cells and the tumor microenvironment (TME). TRT also modulates immune responses, promoting immune-mediated cell death and enhancing the efficacy of combination therapies, such as the use of immune checkpoint inhibitors. The molecular mechanisms underlying TRT involve DNA damage, oxidative stress, and apoptosis, with repair pathways like homologous recombination (HR) and non-homologous end joining (NHEJ) playing critical roles. However, challenges such as tumor heterogeneity, hypoxia, and radioresistance limit the effectiveness of this approach. Advances in theranostics, which integrate diagnostic imaging with TRT, have enabled personalized treatment approaches, while artificial intelligence and improved dosimetry offer potential for treatment optimization. Despite the significant survival benefits of TRT in prostate cancer and neuroendocrine tumors, 30–40% of patients remain unresponsive, which highlights the need for further research into molecular pathways, long-term effects, and combined therapies. This review outlines the dual mechanisms of TRT, direct toxicity and NTEs, and discusses strategies to enhance its efficacy and expand its use in oncology. Full article

The decommissioning and dismantling of nuclear research reactors can lead to a large amount of low- and intermediate-level radioactive waste. For repositories, the materials must be kept confined and safety must be ensured for extended time spans. Waste is encapsulated in concrete, which leads to alkaline conditions with pH values of 12 and higher. This can be advantageous for some radionuclides due to their precipitation at high pH. For other materials, such as reactive metals, however, it can be disadvantageous because it might foster their corrosion. The Studsvik R2 research reactor contained an AlMg3.5 alloy with a composition close to that of commercial Al5154 for its core internals and the reactor tank. Aluminum corrosion is known to start rapidly due to the formation of an oxidation layer, which later functions as natural protection for the surface. The corrosion can lead to pressure build-up through the accompanied production of hydrogen gas. This can lead to cracks in the concrete, which can be pathways for radioactive nuclides to migrate and must therefore be prevented. In this study, unirradiated rod-shaped samples were cut from the same material as the original reactor tank manufacture. They were embedded in concrete with elevated water–cement ratios of 0.7 compared to regular commercial concrete (ca. 0.45) to ensure water availability throughout all of the experiments. The sample containers were stored in pressure vessels with attached high-definition pressure gauges to read the hydrogen-induced pressure build-up. A second set of samples were exposed in simplified artificial cement–water to study similarities in corrosion characteristics between concrete and cement–water. Additionally, the samples were exposed to concrete and cement–water in free-standing sample containers for deconstructive examinations. In concrete, the corrosion rates started extremely high, with values of more than 10,000 µm/y, and slowed down to less than 500 µm/y after 2000 h, which resulted in visible channels inside the concrete. In the cement–water, the samples showed similar behavior after early fluctuations, most likely caused by the surface coverage of hydrogen bubbles. These trends were further supported by mass loss evaluations. Full article

Meningiomas arise from the meningeal layers covering the central nervous system structures. Although most are benign, meningiomas can still cause neurological morbidity due to the mass effect and compression of the surrounding parenchyma. The prognosis also depends on several factors such as growth pattern or location. Morphological imaging approaches, such as MRI and CT, that emphasize intracranial calcifications, vascular patterns, or invasion of major vessels act as the basis of the diagnosis; PET/CT imaging is a valuable diagnostic tool for assessing somatostatin receptor activity in tumors. It enables the visualization and quantification of somatostatin receptor expression, providing insights into tumor biology, receptor status, and potential therapeutic targets. Aside from radiosurgery and neurosurgical intervention, peptide receptor radionuclide therapy (PRRT) has also shown promising results. Somatostatin receptors 1 and 2 are nearly universally expressed in meningioma tissue. This characteristic is increasingly exploited to identify patients eligible for adjuvant therapy using DOTA-conjugated somatostatin receptor-targeting peptides PET. In the treatment of relapsed/refractory meningiomas, PRRT is increasingly considered a safe and effective therapeutic option. It is often supported by artificial intelligence strategies for dose optimization and side-effect monitoring. The objective of this study is to evaluate the safety and benefits of these strategies based on the latest findings. Full article

The presence of radionuclides in environmental media, including sediment, is critical in assessing potential health risks due to external gamma radiation. This study investigates the spatial distribution of natural (Ra-226, Th-232, K-40) and artificial (Cs-137) radionuclides in sediment along the Dixcove coastline, Ghana, using High-Purity Germanium (HPGe) gamma-ray spectroscopy. The activity concentrations of Ra-226 ranged from ~14 to ~23 Bq/kg, Th-232 from ~3 to ~10 Bq/kg, and K-40 from ~44 to ~93 Bq/kg, with Cs-137 levels between 0.2 and 1.3 Bq/kg. The highest concentrations of Ra-226 and K-40 were found On-shore, suggesting terrestrial influence, while Th-232 displayed a more uniform distribution. Radiological risk assessments, including radium equivalent activity (Raeq), annual effective dose (AED), and gamma index (Iγ), confirmed that all measured values were below international safety thresholds, indicating no significant health risk. However, the variability in Cs-137 distribution suggests the need for continued monitoring to assess potential long-term contamination trends. A significant discrepancy was observed when comparing Cs-137 values from this study (maximum 1.3 Bq/kg) with previously reported data (~110 Bq/kg), raising concerns about methodological differences or environmental changes, which require further investigation. To address the observed discrepancies between this study and previous investigations, future research should incorporate in situ measurement techniques for a more comprehensive assessment of Cs-137 distribution. Full article

This paper presents the results of the analysis of the redistribution of cesium-137 (¹³⁷Cs) in the bottom sediments of beaver ponds in two small rivers in the forest-steppe north of the Volga Upland, which is one of the most contaminated areas of the Middle Volga region (European Russia) with artificial radionuclides. This study is based on fieldwork materials, laboratory analyses of the specific radioactivity of ¹³⁷Cs in soil and bottom sediment samples, their granulometric composition, and the content of organic matter in them. The obtained results indicate a significant decrease in the specific activity of ¹³⁷Cs in the direction from near-water-divide surface soils (on average, 54 Bq/kg) to the bottom sediments of beaver ponds of the studied rivers (on average, no more than 6 Bq/kg). A weak (statistically insignificant) tendency towards a decrease in the specific activity of ¹³⁷Cs in the bottom sediments of beaver ponds downstream of rivers was also revealed. With this detected trend, no statistically significant relationship was found between changes in ¹³⁷Cs and changes in the granulometric composition of bottom sediments. However, a relatively good relationship was identified with changes in the content of total organic matter. The stage-by-stage accumulation of sediment thickness in one of the beaver ponds was revealed, with the highest concentration of ¹³⁷Cs in the layer with the highest content of finely dispersed fractions and organic matter. The obtained results indicate that for a correct quantitative assessment of the migration of pollutants (including radioactive ones) in floodplain-channel systems, it is necessary to consider beaver structures (primarily ponds), which act as zones of their intensive accumulation. Full article

Soil samples were collected from a college campus in Taiwan to measure the levels of radionuclides, contributing to the sustainable management of campus environments. A high-resolution HPGe gamma spectrometry system was utilized to measure the activity concentrations of natural radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) and artificial radionuclide (¹³⁷Cs). The activity concentrations of ¹³⁷Cs were not detected in the campus soils, suggesting that artificial radionuclides did not contaminate the soil, supporting sustainable soil quality. However, the average concentrations of ²³²Th and ⁴⁰K with mean values of 53.4 ± 5.1 and 504.5 ± 75.4 Bq/kg dw were higher than the global soil average of 45 and 420 Bq/kg dw, respectively. Meanwhile, the average concentration of ²²⁶Ra with a mean value of 30.1 ± 3.0 Bq/kg dw was similar to the global soil average of 32 Bq/kg. The average outdoor absorbed gamma dose rate (D_ex) and annual effective doses (AED_ex), with a mean of 67.2 nGy/h and 82.4 μSv/y, were found to be higher than the average world levels of 57 nGy/h and 70 μSv/y, respectively. Despite these findings, the radium equivalent activity Ra_eq and external hazard index H_ex, with average values of 145.2 Bq/kg and 0.39, respectively, were below the recommended limit values of 370 Bq/kg and 1.0, respectively. This study provides useful information on the background radioactivity of the study campus, which is crucial for developing sustainable strategies to ensure a safe and healthy environment, indicating that there are no radiological hazards in the soil. Full article

Sorbents based on polyacrylonitrile fiber, containing ferrocyanides of transition metals and manganese oxides (CoMn-PAN and FeMn-PAN) or iron(III) hydroxide (CoFe-PAN) in their structure were obtained, as confirmed by the results of X-ray diffraction and energy-dispersive analyses. The selectivity of the obtained sorbents was investigated, along with their ability to sorb Cs, Ba (as an analog of Ra), P, and Be from various natural media, including river water and seawater with varying salinity of 18.2 and 33.8 ‰. The data show that the sorbents are universal for the recovery of artificial ¹³⁷Cs and natural radionuclides from the natural environments, including complex salt composition (seawater). Researching the obtained sorbents during marine expeditions confirmed the efficiency of the obtained materials based on transition metal ferrocyanides and manganese oxides (CoMn-PAN and FeMn-PAN) for the sorption of ¹³⁷Cs, ⁷Be, ²¹⁰Pb, ²¹⁰Po, ²²⁶Ra, ²²⁸Ra, and ²³⁴Th. Additionally, the sorbent based on transition metal ferrocyanides and iron(III) hydroxide (CoFe-PAN) was effective for the sorption of ¹³⁷Cs, ⁷Be, ³²P, ³³P, ²¹⁰Pb, ²¹⁰Po, and ²³⁴Th. Based on the obtained results, methods for comprehensively determining artificial ¹³⁷Cs and natural radionuclides using these sorbents were developed. Full article

This study investigates the spatial and temporal distribution of the artificial radionuclides ¹²⁹I and ²³⁶U in the Western Mediterranean Sea, focusing on their connection to radionuclide sources and circulation dynamics. Taking advantage of unprecedented precision of accelerator mass spectrometry, both tracers were firstly investigated in 2013. Here, we examine tracer observations obtained along four stations (re-)visited during the TAlPro2022 expedition in May 2022. Distributions of both ¹²⁹I and ²³⁶U were related to water masses and clearly linked to local circulation patterns: a tracer-poor surface Atlantic inflow, a thining of the tracer minimum at intermediate depths, and a higher tracer signal in Western Mediterranean Deep Waters due to dense water formation in the Algero-Provençal basin. The comparison to 2013 tracer data indicated recent deep ventilation of the Tyrrhenian Sea, the mixing of deep waters and enhanced stratification in intermediate waters in the Algero-Provençal basin due to a temperature and salinity increase between 2013 and 2022. We estimate an overall ¹²⁹I increase of 20% at all depths between 0 and 500m with respect to 2013, which is not accompanied by ²³⁶U. This suggests either the lateral transport of ¹²⁹I from the Eastern Mediterranean Sea, or an additional source of this tracer. The inventories of ¹²⁹I calculated for each water mass at the four stations point to the deposition of airborne releases from the nuclear reprocessing plants (La Hague and Sellafield) on the surface Mediterranean waters as the more likely explanation for the ¹²⁹I increase. This work demonstrates the great potential of including measurements of anthropogenic radionuclides as tracers of ocean circulation. However, a refinement of the anthropogenic inputs is necessary to improve their use in understanding ventilation changes in the Mediterranean Sea. Full article

Cardiac amyloidosis (CA) is a cardiac storage disease caused by the progressive extracellular deposition of misfolded proteins in the myocardium. Despite the increasing interest in this pathology, it remains an underdiagnosed condition. Non-invasive diagnostic techniques play a central role in the suspicion and detection of CA, also thanks to the continuous scientific and technological advances in these tools. The 12-lead electrocardiography is an inexpensive and reproducible test with a diagnostic accuracy that, in some cases, exceeds that of imaging techniques, as recent studies have shown. Echocardiography is the first-line imaging modality, although none of its parameters are pathognomonic. According to the 2023 ESC Guidelines, a left ventricular wall thickness ≥ 12 mm is mandatory for the suspicion of CA, making this technique crucial. Cardiac magnetic resonance provides high-resolution images associated with tissue characterization. The use of contrast and non-contrast sequences enhances the diagnostic power of this imaging modality. Nuclear imaging techniques, including bone scintigraphy and positron emission tomography, allow the detection of amyloid deposition in the heart, and their role is also central in assessing the prognosis and response to therapy. The role of computed tomography was recently evaluated by several studies, above in population affected by aortic stenosis undergoing transcatheter aortic valve replacement, with promising results. Finally, machine learning and artificial intelligence-derived algorithms are gaining ground in this scenario and provide the basis for future research. Understanding the new insights into non-invasive diagnostic techniques is critical to better diagnose and manage patients with CA and improve their survival. Full article

^99mTc is a well-known radionuclide that is widely used and readily available for SPECT/CT (Single-Photon Emission Computed Tomography) diagnosis. However, commercial isotope carriers are not specific enough to tumours, rapidly clear from the bloodstream, and are not safe. To overcome these limitations, we suggest immunologically compatible recombinant proteins containing a combination of metal binding sites as ^99mTc chelators and several different tumour-specific ligands for early detection of tumours. E1b protein containing metal-binding centres and tumour-specific ligands targeting integrin α_vβ₃ and nucleolin, as well as a short Cys-rich sequence, was artificially constructed. It was produced in E. coli, purified by metal-chelate chromatography, and used to obtain a complex with ^99mTc. This was administered intravenously to healthy Balb/C mice at an activity dose of about 80 MBq per mouse, and the biodistribution was studied by SPECT/CT for 24 h. Free sodium ^99mTc-pertechnetate at the same dose was used as a reference. The selectivity of ^99mTc-E1b and the kinetics of isotope retention in tumours were then investigated in experiments in C57Bl/6 and Balb/C mice with subcutaneously transplanted lung carcinoma (LLC) or mammary adenocarcinoma (Ca755, EMT6, or 4T1). The radionuclide distribution ratio in tumour and adjacent normal tissue (T/N) steadily increased over 24 h, reaching 15.7 ± 4.2 for EMT6, 16.5 ± 3.8 for Ca755, 6.7 ± 4.2 for LLC, and 7.5 ± 3.1 for 4T1. Full article

The radioactive fission product ⁹⁰Sr has a sufficient half-life (28.8 years) to be detected long after its appearance in the environment. After its uptake into the soil-edible plant system, it enters the food chain and represents a potential source of contamination that threatens human health. Due to these facts, tracking the distribution of the artificial radionuclide ⁹⁰Sr in the soil–edible plant system is a subject of intense research. The tracking of the ⁹⁰Sr radionuclide distribution in the soil profile, as well as in the crops on the long-term experimental fields was carried out using beta radiation spectrometry. The radiochemical analytical method was used to analyze the ⁹⁰Sr content in cultivated soil and crops. The conducted study focused on the experimental substantiation of the developed model for predicting the behavior of ⁹⁰Sr in the cultivated soil–crop system. The results of using the applied radioecological model for the transfer of ⁹⁰Sr from the soil to the above-ground part of crops showed a relatively good agreement with the experimentally determined values of the soil–crop transfer factor, which indicates that the used model can be successfully applied for the prediction of the behavior of ⁹⁰Sr in the soil–soil solution–crop system. Full article

Currently, the production of radioactive waste from nuclear industries is increasing, leading to the development of reliable containment strategies. The deep geological repository (DGR) concept has emerged as a suitable storage solution, involving the underground emplacement of nuclear waste within stable geological formations. Bentonite clay, known for its exceptional properties, serves as a critical artificial barrier in the DGR system. Recent studies have suggested the stability of bentonite within DGR relevant conditions, indicating its potential to enhance the long-term safety performance of the repository. On the other hand, due to its high resistance to corrosion, copper is one of the most studied reference materials for canisters. This review provides a comprehensive perspective on the influence of nuclear waste conditions on the characteristics and properties of DGR engineered barriers. This paper outlines how evolving physico-chemical parameters (e.g., temperature, radiation) in a nuclear repository may impact these barriers over the lifespan of a repository and emphasizes the significance of understanding the impact of microbial processes, especially in the event of radionuclide leakage (e.g., U, Se) or canister corrosion. Therefore, this review aims to address the long-term safety of future DGRs, which is critical given the complexity of such future systems. Full article

The ionic properties of strontium (Sr), a significant artificial radionuclide in the marine environment, were estimated using a stable nuclide-substituting experimental system under controlled laboratory conditions. The bio-accumulation of Sr and its impacts, as well as any possible hidden mechanisms, were evaluated based on the physiological alterations of the sentinel blue mussel Mytilus edulis. The mussels were exposed to a series of stress-inducing concentrations, with the highest solubility being 0.2 g/L. No acute lethality was observed during the experiment, but sublethal damage was evident. Sr accumulated in a tissue-specific way, and hemolymph was the target, with the highest accumulating concentration being 64.46 µg/g wet weight (ww). At the molecular level, increases in the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) and changes in ROS components (H₂O₂, O²⁻, and -OH) and antioxidant system activity indicated that the redox equilibrium state in hemocytes was disturbed. Furthermore, the rise in the hemocyte micronucleus (MN) rate (4‰ in the high-concentration group) implied DNA damage. At the cellular level, the structures of hemocytes were damaged, especially with respect to lysosomes, which play a crucial role in phagocytosis. Lysosomal membrane stability (LMS) was also affected, and both acid phosphatase (ACP) and alkaline phosphatase (AKP) activities were reduced, resulting in a significant decline in phagocytosis. The hemolymph population structure at the organ level was disturbed, with large changes in hemocyte number and mortality rate, along with changes in component ratios. These toxic effects were evaluated by employing the adverse outcome pathway (AOP) framework. The results suggested that the disruption of intracellular redox homeostasis is a possible explanation for Sr-induced toxicity in M. edulis. Full article