Radiation and Environmental Biophysics最新文献

Radiation-related dental caries (RRC) is a rapidly progressing and treatment-resistant condition commonly observed after head and neck radiotherapy. It has traditionally been attributed to radiation-induced salivary gland dysfunction; however, RRC often develops even when appropriate oral care is provided, including fluoride application and regular hygiene practices. This clinical inconsistency suggests that salivary dysfunction alone cannot fully explain the onset and severity of RRC. The direct physicochemical effects of radiation on the organic and inorganic components of dental hard tissues remain poorly understood. In this study, extracted human third molars were subjected to a clinical IMRT protocol, using either a single high dose (20 Gy × 1) or a fractionated regimen (2 Gy/day × 35, total 70 Gy). We then evaluated radiation-induced changes in tooth structure by measuring Vickers microhardness, acid resistance (calcium elution), collagen degradation (autofluorescence), and internal dentin pH. Radiation exposure significantly altered enamel hardness: it increased after 20 Gy but decreased following 70 Gy. Calcium release increased in crown enamel (70 Gy) and root dentin (20 Gy), while decreasing in crown dentin (20 Gy). Autofluorescence imaging showed a significant reduction in dentinal collagen after fractionated exposure. Both groups exhibited an alkaline shift in dentin pH, more pronounced in the single-dose group. These findings provide physicochemical evidence for a non-salivary mechanism contributing to RRC. To effectively prevent RRC, additional strategies to reduce direct radiation damage to dental tissues may be necessary alongside conventional salivary-focused approaches.

The current international radiation protection system is based on the International Commission on Radiological Protection's (ICRP) policy proposal, Publication 103, issued in 2007. Recently, the ICRP has announced its goal to extend the discussion on radiation protection issues beyond the inner bodies, to engage the worldwide radiation protection community. A key step in this direction was the digital workshop "The Future of Radiological Protection" in October 2021 which initiated an in-depth international, scientific debate on the future design of the radiation protection systems. To contribute to this international debate, the German Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV (now BMUKN)) and the Federal Office for Radiation Protection (BfS) in Germany hosted a workshop in Munich in November 2024, bringing together national and international experts to assess and prioritise key topics relevant to the future of radiological protection from a German perspective. The primary aim of the Munich workshop was to exchange scientific and regulatory perspectives in Germany, particularly with regard to the ICRP's "Fit for Purpose" process. Critical topics such as the revision of the justification principle, the refinement of the key criteria for radiation-related risk assessment and impact assessment were central themes of the discussions. This article presents the most important topics and recommendations discussed related to radiation detriment, dose coefficients, societal aspects, non-human biota, impact assessment, radiological emergencies and malicious events as well as the justification and optimisation of medical radiation applications.

Radon is a natural source of radiation and one of the main causes of lung cancer. Since radon is a product of radium decay, it leaks from soil and rock and often accumulates in enclosed spaces. Caves are known for high radon concentrations, especially under certain meteorological conditions when the air circulation in the cave is weak. In this study, the results of radon monitoring in two caves in Croatia, Šparožna Cave and Biserujka Cave, are presented. Radon concentrations were measured continuously in each cave for 14 months. The monthly average concentrations showed a clear seasonal pattern in both caves, with much higher concentrations during summer. In some parts of the monitoring period in Šparožna Cave, diurnal changes in concentrations can also be seen. The highest measured concentration in the Biserujka Cave was 16 kBq/m³, while in the Šparožna Cave a maximum value of 47 kBq/m³ was measured, which is the highest radon concentration measured in any speleological object in Croatia. The effective dose for a 30 min tourist visit to Biserujka was estimated between 0.015 and 0.053 mSv, depending on the month of the visit, while the effective dose for a 3-hour research visit to Šparožna Cave was estimated between 0.029 and 1.28 mSv. These results may help to provide recommendations for limiting the length of stay of employees and visitors in the investigated caves.

This study aimed to compare the quality of radiotherapy treatment plans for stomach cancer on Halcyon™ and VitalBeam^® linacs. Treatment plans were created for 20 stomach cancer patients clinically treated with Halcyon™. The same plans were retrospectively generated for VitalBeam^® under identical planning conditions. Halcyon™ plans were generated with 6 MV FFF (flattening filter-free) beams (800 monitor units (MU)/min), while VitalBeam^® plans used 6 MV flattened beams (600 MU/min), reflecting routinely used configurations and enabling evaluation of FFF versus flattened beam delivery. Conformity index (CI), gradient index (GI), and homogeneity index (HI) for the planned target volume (PTV), and dose metrics for organs at risk (OARs) were assessed. Statistical comparisons were performed using paired tests, where significance was set at p < 0.05. VitalBeam^® achieved a higher CI for the PTV (0.70 ± 0.17) compared to Halcyon™ (0.64 ± 0.14, p = 0.048). GI values were slightly higher with VitalBeam^® (3.41 ± 0.39 vs. 3.26 ± 0.51) but not significantly (p = 0.058). HI values were similar (0.11 ± 0.04 vs. 0.10 ± 0.04, p = 0.308). For OARs, most dose metrics were comparable, while bowel V₁₅ was significantly higher with Halcyon™ (374.6 ± 215.8 cc vs. 346.6 ± 205.9 cc, p = 0.007). It is concluded that Halcyon™ and VitalBeam^® provide comparable VMAT quality for stomach cancer. VitalBeam^® achieved better target conformity and bowel sparing, while Halcyon™ maintained overall efficiency. These differences reflect the multi-leaf collimator (MLC) design and beam setup, highlighting clinical equivalence and tailoring machine choice to needs.

Experimental radiobiology studies rely on exposure platforms that replicate real-world scenarios, yet information on their availability and biological suitability is often fragmented. We thus aimed to map capabilities, access routes, and limitations of European irradiation facilities, with a focus on Germany and briefly contextualized it with selected platforms in the United States of America (U.S.). Single-source systems (X-ray, gamma, alpha/beta) are widely available for cell/animal work, but mixed-beam platforms with controlled conditions and traceable dosimetry are scarce and oversubscribed while alpha/radon analogue setups vary in geometry and atmosphere control, hindering comparability. Large user facilities (reactors, cyclotrons, space-simulation) offer powerful modalities but often lack clearly documented biological access procedures. Here, the selected U.S. facilities provide more explicit user pathways (proposal, fee-for-service, programmatic access). Priorities for Europe should thus include standardized, incubator-compatible mixed-beam systems; a more harmonized reporting of dosimetry/environmental parameters; and a better visibility of biological access in infrastructure catalogues. Ongoing coordination initiatives can underpin these improvements, strengthening reproducibility and access.

The disposal of agricultural waste such as rice husk remains a significant environmental challenge, yet it offers potential for conversion into value added materials such as glass. This study aimed to evaluate radiation shielding efficacy of low-density glasses developed from an abundant agricultural waste i.e. White Rice Husk Ash (WRHA). For this purpose, photon attenuation parameters (Half Value Layer, Linear Attenuation Coefficient, Effective Atomic Number, Transmission Factor) for X-rays employing FLUKA Monte Carlo / EpiXS database and charged particle interaction parameters (Projectile range, Effective Atomic Number) for electrons, protons, He and C ions were determined through SRIM / PAGEX / ESTAR databases. WRHA glasses exhibited linear attenuation coefficient (LAC), effective atomic number (Zeff) and half-value layer (HVL) values in the range of 0.77-8.47 cm^-1, 17.12-25.75 and 0.082-0.904 cm, respectively over 40-120 keV photons. The calculated CSDA ranges for electrons lies between 0.52 and 43.16 g/cm², while projectile range falls within 12.98-151.39, 3.17-13.69, 1.53-662 μm for protons, alpha particles and carbon ions over 1-250 MeV projectile energy. Comparative analysis with low density glasses synthesized from artificial resources concludes with superior radiation shielding competency of WRHA based glasses derived from agricultural waste.