International journal of radiation biology最新文献

Purpose: Human exposure to mixed ionizing radiation fields presents challenges in understanding subcellular effects due to heterogeneous energy deposition. This study investigates DNA damage in primary endothelial cells exposed to monoenergetic neutrons (2.5 or 15.1 MeV), which generate complex secondary charged particle fields.

Materials and methods: Cells were irradiated on a human torso water phantom at 0.13 or 2.11 cm mean depth, 3.20 cm from the neutron source. Three independent experiments were performed per setup at low absorbed doses (<0.12 Gy), estimated from neutron fluence and Monte Carlo simulations (Geant4). DNA damage was assessed by $\gamma$-H2AX foci formation 30 minutes post-irradiation.

Results: Both experimental and simulation data showed higher foci yields at 2.5 MeV compared with 15.1 MeV across all geometries. Simulated DNA DSBs and foci per nucleus increased with dose within the investigated low-dose range (≤0.14 Gy). DSB induction was 37.5-38.6 DSBs per nucleus per Gy at 2.5 MeV versus 22.2-26.5 at 15.1 MeV. Simulated foci yields ranged from 14.3 to 21.7 foci per nucleus per Gy, agreed with experimental results despite dose variability. These findings are in line with the ICRP's energy-dependent weighting factors, indicating greater biological impact at lower neutron energies. Linear foci patterns, observed in 3.9-18.6% of nuclei, appeared perpendicular to neutron incidence. MINAS TIRITH simulations linked these tracks to secondary protons (LET_modal ∼4-19 keV·µm^-1) and $\alpha$ particles at 15.1 MeV neutrons (LET_modal ∼58-107 keV·µm^-1).

Conclusions: This study advances understanding of energy-dependent biological effects in neutron fields, and highlighting the complex, heterogeneous nature of low-dose neutron exposure.

Purpose: Treating nasopharyngeal cancer with radiotherapy often causes radiation-induced temporal lobe injury. This study aimed to investigate whether F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging features extracted from the temporal lobe changed after radiotherapy in nasopharyngeal cancer patients.

Methods: Twenty-two FDG PET textural features were extracted from low-irradiated (less than 20 Gy), 20 Gy-irradiated, 30 Gy-irradiated, and 40 Gy-irradiated areas in the temporal lobe from 24 nasopharyngeal cancer patients who underwent both staging (PET1) and post-radiotherapy (PET2) PET/CT with/without surveillance PET/CT (PET3). Values of FDG PET textural features were compared between PET/CT scan.

Results: On comparison analysis, 30 Gy-irradiated and 40 Gy-irradiated areas on PET2 demonstrated lower values of standardized uptake value (SUV) histogram-based skewness and gray-level co-occurrence matrix (GLCM) correlation, but, significantly higher values of GLCM contrast and neighborhood gray-tone difference matrix (NGTDM) busyness than those on PET1. These four features maintained their differences on PET3 as compared with PET1. The GLCM correlation of the 40 Gy-irradiated area remained statistically significant after false discovery rate correction (adjusted p = .044). On correlation analysis, the volume of the 40 Gy-irradiated area showed significant correlations with changes in SUV histogram-based skewness and NGTDM busyness between PET1 and PET2 (p < .05). Temporal lobe necrosis was found in one patient who showed markedly decreased SUV histogram-based skewness and increased NGTDM busyness on PET2.

Conclusions: Changes of PET imaging features after RT were found in the temporal lobe areas receiving >30 Gy in nasopharyngeal cancer patients. FDG PET/CT textural features might provide exploratory imaging biomarkers for characterizing radiation-induced temporal lobe injury after radiotherapy.

Purpose: Gamma-ray mutagenesis is a widely used technique in plant breeding, but its efficiency depends on the developmental stage, genotype, and timing of irradiation after pretreatment. The aim of this study was to determine the radiosensitivity of two Korean tobacco cultivars, Hyangcho and KB113LC, across developmental stages and to explore whether methyl jasmonate (MeJA) treatment can modulate the expression of target gene sets to enhance mutation induction.

Materials and methods: Tobacco seeds (ranging from 0 to 1000 with 100 Gy steps) and plants at the vegetative and reproductive stages (ranging from 0 to 200 with 25 Gy steps) were irradiated with γ-rays, and growth parameter data were collected to determine 50% reduction dose (RD₅₀) values. The non-irradiated control plants at vegetative and reproductive stages were treated with 500 µM MeJA by foliar spraying, and temporal expression of MeJA-responsive and nicotine biosynthesis-related genes was assessed using qRT-PCR over a 0-48 h period.

Results: The RD₅₀ mean values of each parameter varied by cultivar and stage, with Hyangcho (mean 66 Gy) showing greater radiosensitivity than KB113LC (mean 79 Gy) at both the vegetative and reproductive stages but greater resistance at the seed stage (mean 405 vs. 312 Gy, Hyangcho vs. KB113LC). MeJA treatment induced no obvious physiological alterations; however, the expression of early-response genes (e.g., NtJAZ1, NtMYC2a) peaked at 0.5-1 h post-MeJA treatment, while late-response genes (e.g., NtERF189, NtQPT2) peaked at 16-32 h, with NtODC showing particularly strong activation in KB113LC.

Conclusions: The study findings support the introduction of a practical framework for stage- and genotype-specific γ-ray mutagenesis in tobacco, guided by the timing of MeJA-responsive gene activations. Based on the literature, MeJA pretreatment is assumed to potentially increase mutagenesis efficiency; our data define optimal conditions for testing this hypothesis, supporting the development of tobacco mutant populations, including low-nicotine tobacco lines aligned with evolving public health guidelines.

Purpose: Radiotherapy (RT) remains a cornerstone in breast cancer (BC) treatment. While RT is effective, exposure to surrounding healthy tissues can lead to chromosomal damage and potentially increase the risk of secondary cancers. This study investigated chromosomal damage in circulating lymphocytes of BC patients receiving different RT schemes: ultra-hypofractionation in five fractions (UHF) and moderate hypofractionation in either 10-15 fractions (MHF-low) or 20 fractions (MHF-high). We also aimed to investigate how RT parameters influence MN yields in lymphocytes of BC patients. Additionally, the in vitro chromosomal radiosensitivity of primary and second primary BC patients was evaluated.

Materials and methods: Blood samples were collected pre- and post-RT from 182 primary and 50 second primary BC patients. Chromosomal damage was assessed in lymphocytes using the cytokinesis-block micronucleus (CBMN) assay. To evaluate chromosomal radiosensitivity, all blood samples were irradiated in vitro with 1 Gy of X-ray before performing the CBMN assay. Associations of MN yields with cancer type, RT scheme, lymph node irradiation, boost dose delivery, and irradiated body volume were analyzed using linear regression and linear mixed-effects models.

Results: Our findings indicated no difference in MN yields between primary and second primary BC patients. MHF-high RT scheme was associated with the highest MN induction, while the UHF scheme resulted in the lowest. Additionally, increased chromosomal damage was correlated with higher total tumor doses, larger irradiated volumes, and lymph node irradiation. No significant difference in in vitro chromosomal radiosensitivity was observed between primary and second primary BC patients.

Conclusions: Shorter RT scheme with higher dose per fraction may mitigate cytogenetic damage in circulating lymphocytes, offering potential advantages in long-term safety profiles. In vitro chromosomal radiosensitivity, as assessed by CBMN assay is not a hallmark for second primary BC risk.

Purpose: The objective of this study was to identify mutant lines developed through gamma irradiation that demonstrate adaptability to semiarid environments and possess enhanced agronomic traits.

Materials and methods: In this study, the cultivars Oğuz-2002 and Anadolu Pembesi-2002 were used as control, alongside seven mutant lines developed through mutation breeding. Yield trials were conducted during the 2019 and 2020 growing seasons using a Randomized Complete Block Design with four replications.

Results and conclusions: A statistically significant variation (p < .01) was observed among the genotypes in terms of both biological yield and grain yield, indicating considerable potential for genetic improvement. Upon analysis, the mutant line OG802 exhibited the highest biological yield (4.23 t ha^-1), while the highest grain yield (0.98 t ha^-1) was recorded in the OG602 line. The OG802 line demonstrated a significant increase in biological yield compared to the control cultivars, without any compromise in grain yield. Additionally, OG802 showed greater adaptability to semiarid conditions than the control cultivars. These results suggest that gamma irradiation-induced mutations can enhance biomass productivity and stress resilience without negatively impacting seed production. Such improvements may be attributed to altered physiological or morphological traits, including improved water-use efficiency or biomass allocation. In conclusion, the OG802 mutant line holds strong potential for the cultivation of Hungarian vetch in semiarid environments, owing to its superior biological yield and enhanced adaptability to harsh climatic conditions. These findings underscore the effectiveness of gamma radiation-induced mutation breeding as a promising approach for developing new, climate-resilient genotypes in future breeding programs.

Purpose: The aim of this study was to develop and compare two intelligent model for stratifying the severity of acute radiation syndrome (ARS) in humans based on clinical, hematological, and radiobiological parameters.

Method: The high inter-individual variability of clinical parameters and the infeasibility of conducting randomized studies in radiation medicine necessitated the use of machine learning approaches for model development. The study utilized retrospective data from 1519 patients affected by radiation incidents with outcome-compared clinical follow-up. To construct the stratification model, algorithms of linear discriminant analysis (LDA) and gradient boosting were employed, enabling multilevel classification based on 15 clinical and radiobiological indicators.

Results: The gradient boosting-based model demonstrated the highest accuracy in determining ARS severity. The area under the ROC curves (AUC) reached 0.92, confirming the high predictive value of the proposed approach. To improve interpretability, SHapley Additive exPlanations (SHAP) were applied, identifying the most informative features: cytogenetically estimated radiation dose, exposure duration, markers of inflammatory response, and indicators of radionuclide incorporation.

Conclusions: The developed model is adapted for clinical use and can be implemented as a standalone software tool under resource-limited conditions. Its deployment enables improved medical triage accuracy and reduces the risk of decision-making errors in emergency situations associated with human radiation exposure.

Cell survival curves are a foundational tool in radiobiology and radiation research. We present SDAnext, an open-source MATLAB application providing an intuitive graphical user interface for survival data analysis. The software supports validated data import, fitting to widely used analytical models (Linear, Quadratic, Linear-Quadratic, Linear-Quadratic-Cubic, and Linear-Quadratic-Linear), and publication-ready visualization. SDAnext implements weighted least squares fitting with optional robust estimators, explicit handling of experimental uncertainties, automated model scanning with a goodness-of-fit ranking and bidirectional dose-survival evaluation. Derived radiobiological quantities, including α/β ratios with uncertainty propagation, are computed when applicable. A dedicated multi-session viewer enables cross-dataset comparisons and integrated relative biological effectiveness analysis, with explicit reference selection. The application can be used from MATLAB or as a standalone Windows executable (via MATLAB Runtime). This Technical Note describes the software architecture, input format and workflow, fitting and evaluation features, visualization tools and typical usage scenarios.

Purpose: Conventional radioprotectants are designed to be administered before radiation exposure, while few have been identified that are effective when administered post-exposure. Irradiation generates intracellular reactive oxygen species (ROS) that induce mitochondrial damage, causing the release of mitochondrial contents into the cell cytoplasm and ensuing cell death. This mitochondrial damage occurs a few hours after radiation exposure, so mitochondria-targeted radioprotection can be effective when administered post-exposure. Here, we examined the efficacies of the glutathione (GSH) peroxidase activators melatonin and mitoEbselen-2 against radiation-induced mitochondrial damage.

Materials and methods: Human TIG-3 fibroblasts were exposed to ionizing radiation (IR), and cGAS-positive cytosolic DNA was detected by immunostaining with double-strand DNA and cGAS antibodies as an indicator of mitochondrial (mt)DNA leakage. Mitochondrial membrane potential (Δψm) was also measured using JC-1, while radiation-induced senescence was detected by β-gal staining. Mice were exposed to whole-body irradiation with or without melatonin treatment to assess radioprotective efficacy in vivo.

Results: Radiation exposure induced mitochondrial damage in TIG-3 cells as evidenced by cytosolic mtDNA leakage, Δψm depolarization, and accelerated cellular senescence. Melatonin and mitoEbselen-2 protected against both irradiation-induced and H₂O₂-induced mitochondrial damage, suggesting that these agents act as ROS scavengers. Melatonin also maintained Δψm after irradiation and inhibited cellular senescence. However, prolonged mitoEbselen-2 treatment indicated potential cytotoxicity as shown by Δψm loss. Melatonin mitigated the release of exosome mtDNA into the plasma of mice, as well as radiation-induced damage to blood cells and testicular tissue.

Conclusions: Melatonin can protect against irradiation-induced mitochondrial damage, suggesting utility for mitigating the health effects of accidental radiation exposure.

Purpose: Barite (BaSO₄) is one of the most ubiquitous sulfate minerals in mineral deposits and is suitable for electron spin resonance (ESR) dating. In sea-floor hydrothermal deposits with barite, ²²⁶Ra and ²²⁸Ra, which substitute for Ba in barite, are the main sources of natural radiation together with their daughter nuclides. In ESR dating, the contribution of ²²⁸Ra is often ignored because it is unobservable in most samples due to its short half-life. However, this may not be appropriate for certain young samples in which ²²⁸Ra has already decayed out. In this study, we estimated the initial ²²⁸Ra activity in such barite samples, evaluated its contribution to natural radiation dose, and applied age corrections.

Materials and methods: We assumed that the initial ²²⁸Ra/²²⁶Ra ratio incorporated into barite was identical to the present-day ratio in hydrothermal fluids. This ratio was determined by gamma-ray spectrometry of Mn fibers, which was deployed on the seafloor to absorb Ra from the hydrothermal fluid. Independently, the natural radiation doses accumulated in barite extracted from the sulfide- and sulfate-rich deposits were determined by ESR. Using the estimated initial ²²⁸Ra activity, the extinct contributions of ²²⁸Ra and its daughter nuclides to the total natural dose were calculated, and age corrections were applied to barite samples collected from the Higashi-Aogashima Knoll Caldera hydrothermal field.

Results and conclusions: The conventional ESR ages of two barite samples, in which ²²⁸Ra was not detected, were 973 and 357 years. After correction for the possible contribution of extinct ²²⁸Ra and its daughters, the age differences were only about 2 years. This indicates that the contribution of ²²⁸Ra is negligible in practice unless the initial ²²⁸Ra/²²⁶Ra ratio in particularly high. However, it is still necessary to investigate further if the fluid ratio may vary spatially or temporally.

Purpose: While cigarette smoke (CS) is known to modify the risk of radon-induced lung cancer, the mechanisms remain poorly understood. Experimental studies on their combined effects are limited by the lack of suitable in vitro exposure platforms. This study provides proof-of-concept validation of a novel ALI exposure system for controlled, simultaneous exposure to radon and CS.

Materials and methods: The system comprises a ²²⁶Ra source, radon monitor, smoking machine, particle counter, siphon mixing unit, and an ALI system. The CS unit maintained the target concentration at 5 mg/m³ and induced dose-response toxicity in BEAS-2B cells following 0.5, 1 and 2 h exposures. For a 2-h radon exposure, the estimated average dose to the cells was 1 mGy (range 0.3-7.5 mGy), with a localized dose of 171 mGy per hit nucleus.

Results: Separate exposure to radon (2 h, 228 ± 54 kBq/m³) and CS (1 h, 5 mg/m³) resulted in 75 ± 9% and 83 ± 16% cell viability, respectively, while combined exposure led to a significantly lower cell viability (55 ± 8%). A trend toward an increase in pro-inflammatory IL-8 secretion was noted for all exposures; however, it did not reach statistical significance.

Conclusion: The developed ALI-based exposure system enables precise dosimetry and biological assessment, establishing a validated proof-of-concept platform for future research on environmental co-exposures.