Salt domes are considered potential host rocks for nuclear waste disposal. Therefore, it is of particular interest to characterize nearby groundwater flow, which is driven by density differences from salt and temperature gradients. Thermohaline convection and radionuclide transport in fractured-porous media are investigated near a salt dome using 2D numerical simulations. A fractured thermohaline convection problem near a salt dome was defined using random fracture networks consisting of horizontal and vertical fractures. The basal temperature boundary condition (constant temperature or constant heat flux) was identified as a key methodological assumption that strongly influences thermal-only convection near a salt dome. The presence of fractures can enhance thermohaline convection strength. Matrix diffusion, porosity, and hydraulic conductivity significantly affect convection and radionuclide migration. Fracture networks with longer fractures or higher fracture density show stronger thermohaline convection and further radionuclide transport. Thermohaline convection and radionuclide transport depend highly on the particular realization of the fracture network. Individual fracture positions, lengths and orientations critically influence thermohaline convection strength and radionuclide migration. Fractures aligned with the dominant flow direction strengthen convection and enhance advective transport, whereas fractures orthogonal to the flow direction suppress convective strength and limit radionuclide migration. These findings suggest that fractures may introduce substantial uncertainty when simulating thermohaline convection and radionuclide transport near salt domes, which must be considered in the safety assessment of potential nuclear waste repositories.
The development of effective therapeutic radiopharmaceuticals requires careful consideration in the selection of the radionuclide. The in vivo targeting and clearance properties of the carrier molecule must be balanced with the decay properties of the attached radionuclide. Radionuclides for therapeutic applications fall into three general categories: beta-particle emitters, alpha-particle emitters, and Auger and Coster-Kronig-electron emitters following electron capture. Alpha particles and Auger electrons deposit their energy over short distances with a high LET that limits the ability of cells to repair damage to DNA. Despite their high levels of cytotoxicity, the relatively short range of alpha particles requires binding of the carrier molecule to most cancer cells within a tumor in order to be effective. Because of the extremely short range of Auger electrons, the radionuclide must be carried directly into the nucleus to elicit high radiotoxicity, making it necessary to deliver the radionuclide to every cell within a tumor cell population. These characteristics impose rigid restrictions on the nature of the carrier molecules for these types of particle emitters but successful targeting of these types of radionuclides could result in high therapeutic ratios. Most beta-emitting radionuclides are produced in nuclear rectors via neutron capture reactions; however, a few are produced in charged-particle accelerators. For radionuclides produced by direct neutron activation, the quantities and specific activities that can be produced are determined in large part by the cross-section of the target isotope and the flux of the reactor. Many applications (e.g., therapeutic bone agents, radiolabeled microspheres, radiocolloids) do not require high-specific activities and can therefore utilize the wide range of radionuclides that can be produced in sufficient quantity by direct neutron activation. Other applications (e.g., MAb labeling) require high-specific activity radionuclides in order to deliver a sufficient number of radionuclide atoms to the target site without saturating the target or compromising the integrity of the carrier molecule. Most radionuclides, produced at NCA levels in reactors, are produced via indirect reactions. High-specific activity beta emitters can also be obtained from radionuclide generator systems where the longer-lived parent radionuclide may be obtained from direct neutron activation, as a fission product, or from charged-particle accelerators. It is essential that the half-life of a radionuclide used in RNT be compatible with the rates of localization in target tissues and clearance of the carrier molecule from normal tissues. This consideration is especially important for the various MAbs and their fragments that are currently under investigation as carrier molecules to RIT.(ABSTRACT TRUNCATED AT 400 WORDS)
Observed global warming has profoundly affected the world's oceans, which are experiencing increasingly frequent marine heatwaves and a slowdown of the Global Meridional Overturning Circulation. These changes disrupt ocean circulation patterns, alter biogeochemical cycles, enhance surface ocean acidification, and drive poleward migration of marine organisms. Marine radionuclides (e.g., 3H, 14C, 90Sr, 129I, 134Cs, 137Cs, and Pu isotopes), released from nuclear activities since the 1940s, provide time-resolved tracers of oceanic processes owing to their well-documented input functions and distinct chemical behaviors. Their distributions in seawater, bottom sediments, and marine biota have recorded climate-driven modifications in ocean circulation and stratification. The Pacific Ocean, the largest ocean basin on Earth, has undergone changes in recent decades under ongoing climate forcing. Long-term radionuclide observations indicate a decline in vertical mixing in the upper North Pacific Ocean, likely associated with enhanced stratification. Variability linked to Asian monsoon systems and El Niño-Southern Oscillation (ENSO) events is also clearly reflected in radionuclide records from the marginal seas of the Northwest Pacific. Radionuclide datasets provide essential reference benchmarks for calibrating and validating Ocean General Circulation Models and Earth System Models under future climate scenarios. To strengthen predictive capability, coordinated international, high-resolution sampling programs covering the entire world ocean are required, together with measurement campaigns employing newly developed ultra-sensitive analytical techniques. Particular attention should be given to the Southern, Arctic, and Subarctic Oceans because of their critical role in the global climate system and the current scarcity of comprehensive radionuclide data.
Type 5 insular and paralimbic gliomas are surgically challenging because resection is limited by perforator-rich vascular anatomy and eloquent subcortical pathways, often leaving clinically relevant residual disease. We evaluated a precision-oncology workflow integrating multimodal preoperative planning, transsylvian microneurosurgical resection, and postoperative radionuclide-oriented stratification. This retrospective study included 38 adults with type 5 insular and paralimbic gliomas treated through a transsylvian approach. Structural magnetic resonance imaging (MRI), T2/fluid-attenuated inversion recovery imaging, diffusion tensor tractography, and vascular mapping were integrated to define operative corridors and safety boundaries. Early postoperative MRI was used to assess extent of resection, neurologic outcome, and residual-disease category, which was then linked to standard follow-up, radionuclide-oriented reassessment, or targeted radionuclide therapy candidacy. Gross total resection was achieved in 72% of patients, subtotal resection in 21%, and partial resection in 7%. No new neurologic deficit occurred in 80% of patients, transient deficits in 15%, and permanent deficits in 5%, yielding a neurologic preservation rate of 95%. Residual disease was categorized as no significant residual in 55%, surgically constrained residual in 30%, and biologically high-risk residual in 15%. This integrated workflow achieved high rates of maximal safe resection and neurologic preservation while providing a structured postoperative framework for biologically informed residual-disease assessment, radionuclide-oriented reassessment, and targeted radionuclide therapy candidate selection in surgically complex gliomas.
Lung cancer is the leading cause of cancer‑related mortality worldwide. Current therapies continue to face challenges such as drug resistance and tumour heterogeneity. Radionuclide‑drug conjugates (RDCs) represent an emerging theranostic platform designed to precisely irradiate tumours. This review aims to systematically outline the landscape of advances in RDCs for lung cancer, and provides a forward‑looking perspective on next‑generation RDCs. This analysis was based on preclinical and clinical data retrieved from PubMed and ClinicalTrials.gov, with all records reviewed up to January 2026. Studies were exhaustively surveyed across most radionuclides relevant to RDCs in lung cancer, following the periodic table to ensure comprehensive coverage. In lung cancer, a total of 66 RDCs have been screened, with 30 having entered early‑phase clinical trials. Among completed trials, RDCs underwent a transition from initial 131I/90Y‑labelled antibodies toward 177Lu‑labelled somatostatin receptor (SSTR)‑targeting peptides. SSTR remains the dominant target, with a notable shift from agonists to antagonists. Meanwhile, fibroblast activation protein (FAP), epidermal growth factor receptor (EGFR), and programmed death‑ligand 1 (PD‑L1) are receiving growing attention. Peptides and antibodies are equally employed, with bispecific antibodies (bsAbs), single‑domain antibodies (sdAbs), and cyclic peptides advancing rapidly. Furthermore, nanoparticles (NPs) offer versatile platforms, and pretargeting or dual‑targeting strategies are being developed to improve both efficacy and safety. Crown chelators and bipyridine derivatives provide more stable chelating options. Although 177Lu remains the mainstay, α emitters and emerging mixed‑decay radionuclides like 161Tb are gaining ground. Combination therapies are also being investigated to enable first‑line application. Despite recent progress in RDC development, challenges such as off‑target toxicity, radiation resistance, and radionuclide production remain. Next‑generation RDCs hold promise to overcome these barriers by novel radionuclides, personalised dosimetry, multifunctional delivery platforms, and multidrug combination strategies. Collectively, these innovations will propel RDCs into a personalised, precision theranostic platform for lung cancer.
Systemic radionuclide therapy has become a cornerstone in the management of advanced gastro-entero-pancreatic neuroendocrine tumours (GEP-NETs). Following the establishment of β-emitting peptide receptor radionuclide therapy (PRRT) as an effective treatment for somatostatin receptor positive NETs, recent clinical and translational advances have substantially expanded its therapeutic scope. Several pivotal randomised trials published within the past 18 months justify a reassessment of radionuclide treatment strategies in GEP-NETs. Recently published results of randomised phase III trials support a broader and more strategic use of PRRT, such as in selected high-grade well differentiated NETs. Direct comparisons of PRRT and targeted therapies redefine therapeutic sequencing. Radiosensitising combinations and next-generation theranostic platforms, including alpha-emitting radionuclides, are entering late-phase development. Radionuclide therapy in GEP-NETs is transitioning from a late-line option toward a flexible, biology-driven treatment strategy with important implications for clinical practice.
Accurate assessment of radionuclide distributions at the cellular and subcellular scales is essential for targeted alpha therapy, as cell-scale dosimetry is needed due to the short range of alpha particles. Although radioluminescence microscopy (RLM) enables optical visualization of alpha particle tracks, single-focal plane imaging cannot reliably localize decay origins due to oblique particle trajectories and the lack of depth information. This study aims to establish a multifocal RLM-based framework for quantitative localization of alpha emitting radionuclides.
Approach: A multifocal RLM system was modeled using Monte Carlo simulations (OpenTOPAS), incorporating alpha particle transport, scintillation photon generation, and ray tracing-based image formation. Simultaneously acquired RLM images at two focal planes within a GAGG:Ce scintillator were generated. A reconstruction pipeline was developed to localize decay origins by extracting track centroids in each focal plane, matching corresponding tracks between planes based on spatial and intensity criteria, and extrapolating inferred trajectories to estimate emission positions. The framework was evaluated for monoenergetic alpha particles (4-8 MeV) and for 225Ac decay chains under secular equilibrium, including uniformly distributed and cell-confined source configurations.
Main results: For monoenergetic sources, the proposed approach achieved detection rates exceeding 85% for alpha energies representative of 225Ac daughters, with spatial resolution near 2 µm. Under 225Ac decay chain conditions, median lateral localization errors of approximately 1-2 µm were obtained at activity levels up to 0.2-0.4 kBq per cell, which are relevant to targeted alpha therapy studies. The results further revealed trade-offs between detection efficiency, source density, and particle energy, providing quantitative guidance for experimental design.
Significance: This study demonstrates the feasibility of multifocal RLM as a quantitative framework for micrometer-scale localization of alpha-emitting radionuclides. By extending conventional RLM from qualitative track visualization to decay origin estimation, the proposed approach provides a physical foundation for experimental validation of subcellular radionuclide distributions.
Assessing the environmental legacy of historical test sites for nuclear weapons and radiological warfare agents (RWAs) is critical for understanding long-term isotopic evolution and evaluating land safety. This study evaluates artificial radionuclide levels (241Am, 137Cs, 90Sr and 239+240Pu) in the land cover of Site '4', a historic RWA testing ground in the Republic of Kazakhstan. Within the 37 km2 area analysed via pedestrian and discrete gamma spectrometric surveys, 14 radioactively contaminated locations with gross gamma count rates exceeding the experimentally established baseline of 180 cps were identified, totalling ∼0.37 km2. Soil analysis revealed 90Sr activity concentrations exceeding those of other artificial radionuclides by several orders of magnitude, with the highest values at all sampling points recorded in the upper soil layer (0-10 cm). From the vertical 90Sr distribution within the soil profile, two distribution patterns were identified: (1) high migration into the 10-20-cm layer and below, and (2) high activity concentrations in the 0-10-cm layer, followed by a sharp decrease in the 10-20-cm layer. This differing distribution pattern is attributed to the use of liquid vs. powdered RWA formulations. The maximum total dose rate of the investigated artificial radionuclides to herbaceous vegetation reached 220 μGy/day, driven primarily by 90Sr exposure. This study fills a critical research gap in the radioecological monitoring of this area and provides precise geographical and radioecological data necessary for the rehabilitation of these lands.
This study conducted a systematic review and meta-analysis of radionuclide concentrations of Cesium-137 (Cs-137), Cesium-134 (Cs-134), Iodine-131 (I-131), Lead-210 (Pb-210), and Potassium-40 (K-40) in milk worldwide, along with an assessment of human health risks, in accordance with the PRISMA guidelines. Pooled radionuclide concentrations were estimated using a random-effects model, while excess lifetime cancer risk (ELCR) was calculated to evaluate carcinogenic effects using the Monte Carlo Simulation (MCS) model. A comprehensive search of Scopus, PubMed, Embase, and Web of Science identified 66 papers (200 data reports, 2000-2025) that cover milk samples from 32 countries. The global pooled mean concentrations (Bq/L) followed the order: K-40: 57.494 > Cs-137: 0.904 > I-131: 0.301 > Pb-210: 0.136 > Cs-134: 0.032. Extreme concentrations were observed in the United Kingdom (Cs-137: 288.000), Syria (I-131: 76.000; K-40: 243.500), and India (Pb-210: 1.080), whereas Mali (Cs-137: 0.003) and Algeria (K-40: 2.349) showed the lowest levels. Probabilistic human health risk assessments revealed that the mean cancer risk (CR) for adults from Cs-137 ingestion exceeded the acceptable limit (1E-4) in the United Kingdom, Austria, South Korea, Serbia, the Czech Republic, Germany, Kazakhstan, and Iceland. For Cs-134, the CR in Finland and France remained below the limit. The CR from K-40 exceeded the limit in Spain, Syria, Bangladesh, Mali, Iraq, Singapore, Thailand, Japan, Italy, and Turkey. For I-131, the limit was exceeded in Syria, Romania, Greece, and Spain. The CR of Pb-210 exceeded the limit in Tunisia, Slovenia, India, the Czech Republic, Italy, and Syria. These disparities reflect variations in environmental contamination, nuclear legacy, and regulatory standards. The results highlight the necessity for strict monitoring, especially in high-risk areas, and promote enhanced agricultural practices and food safety policies to reduce radionuclide exposure through milk consumption.
This study evaluates the drivers of radionuclide spatial heterogeneity in topsoil of the Lake Sevan Basin (Armenia) - the largest high-mountain freshwater body in the South Caucasus - using integrated statistical and spatial analyses. A total of 170 soil samples were analyzed for Ra-226, Th-232, K-40, Cs-137, and gross beta activity, together with in-situ dose was measurement. Statistical analysis revealed strong inter-correlations among natural radionuclides (with Spearman's test) and bimodal distribution patterns for Th-232 and gross beta activity, indicating the presence of distinct source domains. Land-use analysis confirmed significant effects on K-40 and Cs-137 distributions, with higher Cs-137 in low-disturbance soils and lowest in arable land, whereas K-40 was notably elevated in forest soils. The spatial heterogeneity of these parameters was modeled using geostatistical methods including Empirical Bayesian Kriging (EBK) and Getis-Ord Gi* (Gi*) Hot Spot analysis. The analysis identified statistically significant hot spots of Ra-226, Th-232 and radium equivalent activity in southwestern, volcanic-rock-dominated part of the basin, and cold spots in lacustrine-derived soils in the eastern area. K-40 displayed additional enrichment in northwestern agricultural zones, suggesting a potential contribution from long-term agricultural practices. Cs-137 exhibited limited but distinct hot-spot clustering in minimally disturbed soils, reflecting post-depositional fallout processes. Radiological risk assessment revealed Ra-226 and Th-232 as the main risk contributors for the southwestern located settlements. The study demonstrates that integrating statistical inference, spatial modelling, and radionuclide geochemistry enables process-based interpretation of soil radioactivity and provides a transferrable framework for contamination assessment, radioecological targeted monitoring, and management prioritization in complex mountain environments.
This study evaluates the cellular dosimetry of Antimony-119 (119Sb) as a candidate for targeted radionuclide therapy (TRT), using Monte Carlo simulations with the GATE toolkit. The goal is to assess the microdosimetric characteristics of 119Sb as an Auger and Internal conversion electron emitter and compare its performance with other clinically relevant radionuclides-177Lu, 125I, 123I, and 103Pd-across different cellular geometries and emission spectra. Monte Carlo simulations were performed using the GATE toolkit to model energy deposition at the cellular level. Two cell geometries were considered: one with a centrally located nucleus and another with the nucleus adjacent to the cell membrane, reflecting real biological diversity. S-values (absorbed dose per decay) were calculated for three possible locations of radioactivity (nucleus, cytoplasm, and cell membrane). Three emission spectra and two physics models were used to ensure robust results. Simulations were benchmarked against established dosimetry models (MIRDcell, PENELOPE, and Geant4). 119Sb delivered the highest and most localized dose to the cell nucleus, particularly when radioactivity was at the cell membrane, outperforming the other radionuclides tested. Its S-values were up to five times higher than 177Lu and four times higher than 125I in certain configurations. This effect remained strong even when the nucleus was off-center, suggesting 119Sb's effectiveness is independent to nucleus locations diversities. Auger and Coster-Kronig electrons dominated the energy deposition for most isotopes in single cell configurations, while internal conversion electrons contributed significantly for 119Sb in the cytoplasmic and membrane configurations. 119Sb is a promising candidate for TRT of micrometastases and single cancer cells due to its high and stable S-values, especially when radioactivity is localized at the cell membrane. Its dosimetric stability across nucleus positions makes it particularly suitable for therapeutic applications where cellular morphology varies. However, production and radiolabeling challenges may limit its clinical adoption.
Mining the rare earth elements (REEs), critical minerals important in technological applications, introduces concerns regarding the release of airborne REEs and associated radionuclides (U, Th) to surface environments. Despite expanding REE mining development, atmospheric REE sources and depositional pathways remain poorly characterized, particularly in northern regions lacking pre-disturbance baseline data. To establish a biomonitoring framework in the Canadian subarctic (Nunavik, Quebec), we analyzed 50 elements in two dominant fruticose taxa (Cladonia stellaris, Stereocaulon paschale) and soil substrate over six sampling years prior to REE mining. Mixed-effects models revealed significant spatial variability in elemental concentrations (∼40-90%), with species effects predominantly emerging among essential nutrients (Cu, K, Mn, Rb, S, Zn). Lichen-soil relationships indicated REE bioaccumulation was independent of underlying soil geochemistry and instead co-varied with radionuclides (U, Th) and lithogenic elements (Al, Fe, Ti, V, Co), characteristic of regional to long-range geogenic atmospheric transport, likely facilitated by wind erosion across the subarctic landscape. Near localized pollution sources, C. stellaris exhibited distance-based gradients in Ba and REEs within 1 km and captured As, Pb, Cd, and Cr enrichments 10-times background levels, indicating limited anthropogenic inputs consistent with transport emissions, waste incineration, and road dust resuspension. Washed samples retained the majority of REEs, suggesting accumulated REEs are strongly surface-bound or partially internalized, rather than loosely adsorbed. These results establish dominant subarctic lichens as effective atmospheric biomonitors, providing a pre-disturbance geogenic baseline and demonstrating their application to evaluating the potential mobilization of airborne contaminants, including REEs, U, and Th, surrounding future mining activities.
Foregut and hindgut neuroendocrine tumors (NETs) contribute significantly to the global NET burden especially in Asian population; however, these cohorts are sparse and underrepresented in current trials assessing peptide receptor radionuclide therapy (PRRT) in gastroenteropancreatic (GEP) NETs. This single-centre study evaluates the efficacy and safety of PRRT in advanced foregut and hindgut NETs. Retrospective data evaluation of consecutive patients with biopsy-proven metastatic foregut (gastric, lung and thymic NETs) and hindgut NETs (colorectal, anal and sacral NETs) who underwent PRRT from 2014 to 2024 at a tertiary care hospital was done. Up to four cycles of 177Lu-DOTATATE (7.4 GBq/cycle) were administered intravenously every 6-8 weeks along with nephroprotection. Interim and end-of-treatment 68Ga-DOTANOC PET/CT scans were acquired for response evaluation, based on RECIST v1.1. Objective response rate (ORR), disease control rate (DCR), best biochemical response, toxicity profile, quality-of-life scores, progression-free survival (PFS) and overall survival (OS) were assessed. Thirty-four patients (median age-56 yrs) with foregut (n = 16) and hindgut (n = 18) NETs received a total of 111 cycles (range 1-4) of 177Lu-DOTATATE (median cumulative activity 26.5 GBq). The best ORR and DCR were 45% and 80%, median PFS was 29.7 months (95% CI, 20.3-39.1), and the 1- and 5-year OS rates were 93.8% (95% CI, 85.4-100) & 53.6% (95% CI, 28.6-78.6), respectively, after a median follow-up of 45.3 months. Grade 3 adverse events were observed in only five patients. PRRT appears to be safe and effective treatment modality in advanced foregut and hindgut NETs. More prospective trials are required to validate these findings in larger cohorts.
As peptide receptor radionuclide therapy (PRRT) maintains a key role in the treatment of neuroendocrine tumours (NETs), there is growing recognition of the importance of evaluating patient-reported health related quality of life (HRQoL). To assess this impact meaningfully, validated instruments such as the European Organisation for Research and Treatment of Cancer (EORTC) quality of life questionnaires are invaluable. This study aims to evaluate the impact of PRRT on the HRQoL of patients with NETs, using generic cancer and GI-NET-specific EORTC questionnaires to provide a comprehensive understanding of how PRRT influences patient wellbeing beyond traditional clinical endpoints. Between 2015 and 2025, patients who underwent PRRT at Royal Free London Hospital, and consented to this study, completed GI.NET21 and C30 questionnaires before PRRT is administered at each cycle. Patients who completed the pre-therapy questionnaire and at least one post-PRRT questionnaire were included in this study. The response format of both questionnaires is a 4-point Likert scale. Responses to the questionnaire were linearly transformed to a 0-100 scale using EORTC guidelines. A mean score difference >5 between any treatment cycles was considered clinically relevant, and p <.05 was considered statistically significant. GI.NET HRQoL questionnaire was completed by 267 patients, and C30 questionnaires by 147 patients. There was a statistically significant improvement between the pre-therapy score and all post PRRT treatment cycle scores in symptom scales, disease-related worries, and social function with GI.NET 21. This improvement was visible even after one PRRT cycle. A non-statistically significant improvement in overall score was seen in the pre therapy score and the third post therapy score in the C30 questionnaire. PRRT improves the quality of life and disease-specific concerns of NETs using a NET-specific HRQoL assessment tool.
Twenty-eight composite surface soil samples collected from four ecosystem types across El Kala National Park, Algeria - a United Nations Educational, Scientific and Cultural Organization (UNESCO) Biosphere Reserve. UNESCO Biosphere Reserve - were characterized for 40K, 137Cs, 226Ra, 228Ra, and 232Th by high-purity germanium (HPGe) gamma spectrometry. Mean activity concentrations were 178.7 ± 84.4 Bq kg-1 for 40K, 12.1 ± 9.7 Bq kg-1 for 137Cs, 112.1 ± 30.3 Bq kg-1 for 226Ra, and 25.4 ± 11.8 Bq kg-1 for 232Th-series (all uncertainties reported at coverage factor k = 2). Radium-226 concentrations exceeded the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) worldwide median of ~35 Bq kg-1 by a factor of ~3, reflecting geological enrichment within Tertiary phosphatic sedimentary formations of north-eastern Algeria. Potassium-40 and 232Th concentrations were within worldwide typical ranges; 137Cs was consistent with residual global fallout from mid-twentieth century atmospheric nuclear weapons testing. In-situ absorbed dose rates (park mean 83.8 nGy h-1) include a cosmic radiation contribution of ~35 nGy h-1 that is absent from terrestrial dose rates calculated using UNSCEAR (2000) conversion coefficients applied to site-specific data (park mean 74.8 nGy h-1. Subtracting the cosmic component yields a corrected terrestrial in-situ mean of ~49 nGy h-1 - ~35% below the calculated value - consistent with systematic overestimation by the UNSCEAR semi-infinite source geometry when applied to surface-concentrated (0-15 cm) radioactivity profiles. RESRAD-BIOTA Level 1 ecological screening, applying ICRP Publication 108 protective benchmarks of 10 mGy d-1 for terrestrial animals and 1 mGy d-1 for terrestrial plants, produced sum ratio factors (SRFs) of 0.0119 and 0.146, corresponding to safety margins of 84-fold and 6.8-fold below their respective benchmarks. Both SRF values were well below unity, confirming that Level 1 screening criteria are satisfied without requiring higher-tier assessment for terrestrial animals; a Level 2 assessment is recommended for terrestrial plants given the more constrained margin. Radium-226 dominated total biota dose (53% for animals; 75% for plants). These results establish the first systematic radiological baseline for this ecologically sensitive Mediterranean protected area and demonstrate the applicability of RESidual RADioactivity - BIOlogical Transport of Activity (RESRAD‑BIOTA) graded screening in naturally enriched geological settings.
Freshwater fish are an important source of high-quality protein, essential amino acids, omega-3 polyunsaturated fatty acids, vitamins, and minerals. However, contamination of aquatic ecosystems with toxic elements and radionuclides may compromise both food safety and the nutritional and biochemical integrity of fish. This study aimed to evaluate the association between toxic elements, radionuclides, and biochemical degradation of freshwater fish marketed for human consumption in West Kazakhstan. A cross-sectional observational study was conducted from April to September 2025. A total of 800 samples were analyzed, including 500 fresh freshwater fish specimens representing five species and 300 processed fish products collected from retail outlets supplied by 15 water bodies and one aquaculture facility. Concentrations of lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) were determined using validated standard methods. Radionuclide activity of cesium-137 (Cs-137) and strontium-90 (Sr-90) was also measured. For biochemical analysis, fish were divided into a control group (no detectable contamination; n = 50) and a contaminated group (low-dose Pb and/or Cd detected; n = 50). Nutritional composition, mineral profile, vitamin content, amino acid composition, and fatty acid profiles were analyzed using standardized laboratory techniques. Statistical analysis included effect size estimation, false discovery rate correction, and multivariate modeling. Pb and Cd were detected in fish from 7 of 15 water bodies, with localized exceedances reaching 1.15 mg/kg and 0.245 mg/kg, respectively. As and Hg were not detected, while radionuclide activity remained within permissible limits. Compared with the control group, contaminated fish showed significant reductions in lipid content (-26.3%) and energy value (-12.7%), along with decreases in essential minerals, vitamins, and total amino acid content (-15.8%) (p ≤ 0.05). Omega-3 polyunsaturated fatty acids, particularly eicosapentaenoic acid and docosahexaenoic acid, were markedly reduced. Multivariate analysis confirmed that contamination status was an independent predictor of biochemical deterioration irrespective of species. The findings demonstrate that compliance with regulatory contaminant limits does not guarantee preservation of nutritional quality. Chronic low-dose exposure to Pb and Cd is associated with substantial biochemical degradation of fish muscle tissue, even when organoleptic quality remains acceptable. These results highlight an overlooked dimension of food safety and support the integration of biochemical and nutritional indicators into routine monitoring frameworks to improve consumer protection.
In targeted radionuclide therapy, differences in particle range and radiation quality produce distinct spatial energy-deposition patterns within cell clusters and thereby influence population response. This study aimed to compare the dose deposition, microdosimetric characteristics, and associated population responses of ²²⁵Ac, ²¹¹At, ¹⁷⁷Lu and ¹⁶¹Tb at the cell-cluster scale.
Approach. A cubic lattice cell cluster was constructed by replicating a realistic single-cell PC-3 mesh-type model. PHITS was used to calculate distance-grouped nuclear S values and microdosimetric quantities for different subcellular source localizations. Using fast Fourier transform (FFT)-based convolution together with the saturation-corrected microdosimetric kinetic (MK) model, the dose distribution and population response under different labeling fractions, cell cluster sizes, and lognormal activity heterogeneity were evaluated.
Main results. Convolution-reconstructed cluster-averaged S values agreed well with direct PHITS simulations, with deviations below 5% in most cases. The four radionuclides showed distinct spatial microdosimetric patterns. For ²²⁵Ac and ²¹¹At, the saturation-corrected dose-mean lineal energy, y*, decreased from about 60-70 keV μm⁻¹ in the near layers to below 4 keV μm⁻¹ in the distant layers, whereas the variations for ¹⁷⁷Lu and ¹⁶¹Tb were more gradual. Across subcellular localizations, labeling fractions, cluster sizes and activity distributions, the mean activity per cell required for ²²⁵Ac to achieve a tumour control probability (TCP) of 0.9 remained approximately 3 orders of magnitude lower than that for ¹⁷⁷Lu and ¹⁶¹Tb . Activity heterogeneity further increased the mean nuclear absorbed dose per cell required to achieve the same TCP, with the strongest amplification observed under nuclear localization and for ¹⁶¹Tb.
Significance. This study establishes a rapid convolution-based framework for cell-cluster-scale analysis. Under a unified set of physical inputs and model assumptions, it enables systematic comparison of spatial dose deposition, microdosimetric variation, and population response among radionuclides and across subcellular localization, labeling fraction, cluster size, and activity heterogeneity.
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The long-term geological disposal of radioactive waste necessitates robust risk assessment models to accurately predict radionuclide transfer from contaminated growing media into the human food chain. Iodine-129 (129I) and the rhenium isotopes 186Re and 188Re are of significant regulatory concern due to their anionic mobility, environmental persistence, and high bioavailability. However, current risk assessment frameworks typically rely on the assumption of constant, concentration-independent transfer factors (TFs), a foundational premise that remains largely untested across gradients spanning trace levels to acute phytotoxicity. Through controlled greenhouse experiments, we quantified the concentration-dependent uptake and physiological responses of iodine (0, 50, 100, 200 mg·kg-1) and rhenium (0, 5, 10, 20 mg·kg-1) in lettuce (Lactuca sativa L.). Iodine reached a lethal threshold at 200 mg·kg-1 (EC50: 58.9 mg·kg-1), following a classical monotonic response. Conversely, rhenium exhibited significantly higher phytotoxic potency (EC50: 19.7 mg·kg-1) and a distinct biphasic hormetic response. Concentrations of 5-10 mg·kg-1 stimulated shoot biomass and canopy density, whereas 20 mg·kg-1 induced severe growth suppression. Crucially, TFs for both elements were concentration-dependent, indicating that the constant-TF assumption does not hold under the present conditions. Rhenium demonstrated exceptional mobility with shoot-to-root ratios of 22-52, indicating rapid translocation to edible tissues. In addition, a scenario-based radiological assessment using literature-reported 129I soil activities indicated low screening-level ingestion doses under the modeled conditions. These findings provide vital empirical parameters for refining predictive environmental models and establishing evidence-based soil screening levels supporting human health and radiological risk assessment of radionuclide transfer through crop systems.
Theranostics is the main treatment strategy for well-differentiated neuroendocrine tumors (NETs), using somatostatin receptor (SSTR)-based PET/CT and radiopharmaceutical therapy. SSTR-based PET/CT is an important imaging tool to detect progressive disease after peptide receptor radionuclide therapy, but it sometimes fails to detect disease because of downregulation of SSTRs or changes in grade. Recently introduced fibroblast activation protein inhibitor (FAPI) PET/CT may serve as a promising imaging modality for high-proliferative NETs. A unique case of a pancreatic NET (grade II) is illustrated, which showed progressive liver and skeletal metastatic disease after peptide receptor radionuclide therapy and an increase in grade (Ki-67 proliferation index, 40%-50%) with variable tracer avidity and interlesional heterogeneity on [68Ga]Ga-DOTATATE (no SSTR uptake in liver lesions) and [68Ga]Ga-FAPI-04 PET/CT (intensely tracer-avid liver lesions and non-tracer-avid skeletal lesions). We found that [68Ga]Ga-FAPI-04 PET/CT may be used as a complementary imaging modality to detect FAPI-avid lesions and be considered as another theranostic pair with SSTR-based radiopharmaceutical therapy in patients with NETs.
Radioembolization for hepatocellular carcinoma uses microspheres radiolabeled with yttrium-90 or holmium-166, yet their radiobiological effectiveness has not been directly compared, leaving radionuclide selection uninformed by biological considerations. We assessed the survival and DNA damage induction following 1.5 or 2.5 Gy of [166Ho]Ho-DOTA or [90Y]Y-DOTA delivered over 24 h on three human hepatocellular carcinoma cell lines. Both radionuclides led to a similar, dose-dependent reduction of survival in all cell lines, with a modest but nonsignificant trend towards increased toxicity for [166Ho]Ho-DOTA. Notably, [166Ho]Ho-DOTA induced fewer, but larger DNA damage foci at earlier time points during irradiation, suggesting subtle differences in damage complexity or repair kinetics. These findings suggest that when delivering the same absorbed dose over 24 h, [166Ho]Ho-DOTA and [90Y]Y-DOTA demonstrate comparable cytotoxicity in vitro. These findings imply that in clinical settings, additional factors such as total injected activity and microsphere composition and biodistribution likely exert greater influence on treatment efficacy than radionuclide choice alone.