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/m, while in the Šparožna Cave a maximum value of 47 kBq/m 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.

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.

Radiotherapy for non-small-cell lung cancer (NSCLC) requires precise tumour targeting and monitoring of anatomical changes to optimize outcomes. Daily kilovoltage cone-beam computed tomography (kV-CBCT) enables real-time tracking of tumour volume and electron density changes, which may affect dose distribution and radiobiological outcomes, such as Tumour Control Probability (TCP) and Normal Tissue Complication Probability (NTCP). This study evaluated inter-fractional changes in gross tumour volume (GTV) and electron density using kV-CBCT and their impact on dosimetric and radiobiological endpoints to assess the role of CBCT in adaptive radiotherapy. Twenty inoperable NSCLC patients receiving intensity-modulated radiotherapy (IMRT) with a prescribed dose of 60 Gy in 30 fractions were included in this retrospective study. Daily kV-CBCT images were acquired on the 1st, 15th, and 30th fraction to re-contour GTV and measure electron density changes in the GTV and ipsilateral lung (V30 volume, defined as lung volume receiving ≥ 30 Gy excluding GTV). CBCT images were fused with planning CT for dose recalculation using a Hounsfield unit-to-density calibration. Changes in GTV volume, electron density, maximum dose, and volume receiving ≥ 2.1 Gy/fraction were analyzed. TCP and NTCP were calculated using the Equivalent Uniform Dose (EUD) and Lyman-Kutcher-Burman (LKB) models, respectively. Statistical significance was assessed using ANOVA (p < 0.05). GTV volume decreased significantly by 3.4-59.7% by the 30th fraction (p < 0.05). Mean electron density in the GTV reduced by 3.04% at 30 Gy and 5.76% at 60 Gy, while the V30 volume showed reductions of 4.61% and 17.17% at the 15th and 30th fractions, respectively (p < 0.05). These changes resulted in a 1.39% increase in maximum GTV dose and a 7.48% increase in the volume receiving ≥ 2.1 Gy/fraction by the 30th fraction. TCP increased modestly from 81.91 ± 10.25% to 83.4 ± 11.32%, while NTCP rose significantly from 6.64 ± 2.31% to 10.54 ± 1.94% (p < 0.05). Thus, daily kV-CBCT demonstrated significant GTV volume and electron density reductions during NSCLC radiotherapy, leading to dose heterogeneity and increased NTCP. These findings underscore the potential of CBCT as a tool for adaptive radiotherapy to enhance treatment precision and minimize radiation toxicity. Prospective studies with larger cohorts and clinical outcome data are needed to establish thresholds for adaptive replanning.

Monitoring of Ra in drinking water is critical due to its radiotoxicity and potential health risks. This study presents a novel method for Ra determination in bottled mineral waters using a KMnO-modified fly ash sorbent. The sorbent, prepared by manganese dioxide surface modification, demonstrated significantly enhanced radium sorption capacity. Method validation, including linear regression and equivalence tests, confirmed that the modified fly ash sorbent and commercial MnO-PAN resin yield statistically equivalent results for Ra determination in mineral waters. Thus, it is concluded that application of the modified sorbent represents a reliable and cost-effective alternative to commercial methods. Application to 20 commercially available Slovak bottled mineral waters revealed Ra activity concentrations corresponding to annual committed effective doses ranging from 1 to 154 µSv/y. While the average dose (41.8 µSv/y) remained well below national and international safety limits, three samples exceeded the Slovak regulatory threshold of 100 µSv/y. These findings emphasize the need for ongoing monitoring and demonstrate the suitability of the KMnO-modified fly ash sorbent for routine radiological quality control of bottled mineral waters.

Owing to the use of highly penetrating gamma radiation for medical proposes, radiation shielding is a crucial issue for radiological protection. Lead-free shielding materials are becoming more interesting to solve the disadvantages of lead (i.e., toxicity and heaviness). This study investigates the radiation shielding performance of epoxy resin (ER) and Portland cement (PC) composites enriched with bismuth oxide (BiO) fillers at weight ratios of 20%, 30%, 40%, and 50%, across photon energies ranging from 122 to 662 keV. The results indicate that higher BiO content enhances the linear attenuation coefficient (0.299 to 1.187 cm), radiation protection efficiency (26 to 99%) and lead-equivalent thickness (0.16 to 2.1 cm), demonstrating improved radiation attenuation ability. The transmission factor (TF) was calculated for four different thicknesses of each composite, showing that thicker samples resulted in lower TF values (0.86%) compared to thinner ones (74.16%). Despite being thicker than the standard lead shielding; the composites are half of the weight. Among all tested samples, the ER/Bi50 composite demonstrated the most effective shielding potential. While no full economic or life cycle assessment was conducted, the use of non-toxic components and reduced weight suggests that ER/Bi50 may offer potential advantages in terms of cost-effectiveness and environmental friendliness. Thus, ER/Bi50 with 4 cm thickness is proposed as a promising lead-free alternative to conventional lead-based shielding materials for gamma ray attenuation in medical applications at energies below 356 keV.

This study aimed to establish reference dose-volume parameters for various organs at risk (OARs) across clinically relevant dose-fractionation regimens in breast cancer radiotherapy. It further evaluated the variation in biologically effective doses (BEDs) of OARs as functions of different α/β values and fractionation schedules. The regimens examined include conventional (50 Gy in 25 fractions), moderately hypofractionated (40 Gy in 15 fractions), and ultrahypofractionated (27 Gy-26 Gy in 5 fractions) approaches. Left-sided breast (Br) or chest wall (CW) cancer, with or without supraclavicular fossa involvement, were planned using five-field intensity-modulated radiotherapy (IMRT). Evaluation parameters included heart D0.2 cc, heart mean dose, and ipsilateral (left) lung mean dose. BEDs were calculated for six α/β values: 3.7, 3.0, 2.3, 2.0, 1.8, and 1.7 Gy. Variations between prescribed and achieved doses, along with their corresponding BEDs, were analyzed using one-way ANOVA. This study included 359 patients, with 50 in the ultrahypofractionated group and 309 in the combined moderately hypofractionated and conventional group. For the 50 Gy regimen, left lung mean BEDs ranged from 15.1 ± 4.2 Gy to 21.4 ± 6.2 Gy across different α/β values, suggesting potential risks of radiation pneumonitis or lung fibrosis. In contrast, the 26 Gy regimen yielded lower mean BEDs, ranging from 8.4 ± 1.8 Gy to 14.3 ± 3.3 Gy, indicating a more favourable risk-benefit profile. For the heart, mean BEDs were 6.1 ± 2.1 Gy to 8.6 ± 3.3 Gy with 50 Gy, compared with 3.3 ± 0.9 Gy to 5.7 ± 1.5 Gy with 26 Gy. Heart D0.2 cc BEDs were higher for 50 Gy (69.6 ± 11.6 Gy to 98.2 ± 15.8 Gy) than for 26 Gy (48.3 ± 11.7 Gy to 81.4 ± 18.7 Gy). All differences between prescription doses, OAR doses, and corresponding BEDs were statistically significant (p = 0.003-0.035). It is concluded that this study provided reference OAR dose-volume parameters and BED values across a range of α/β values for conventional, moderately hypofractionated, and ultrahypofractionated breast cancer radiotherapy in a large cohort of Asian women. Data presented here can guide treatment planning, support dose constraint selection, and aid interpretation of dosimetric data, particularly for ultrahypofractionated regimens, where evidence remains limited.

Thyroid doses were estimated for a cohort of 3,183 individuals who were exposed to fallout from atmospheric nuclear weapons tests conducted at the Semipalatinsk Nuclear Test Site (SNTS), Kazakhstan, between 1949 and 1962. The study participants were mostly younger than 21 years of age at the time of their first exposure and lived in settlements near the SNTS. Individual thyroid doses from external irradiation from gamma-emitting radionuclides deposited on the ground as well as internal irradiation from intake of I and short-lived radiotellurium and radioiodine isotopes (Te+I, I, and I) with locally produced foodstuffs and inhalation of contaminated air during the passage of the radioactive cloud were reconstructed for the cohort. Estimated thyroid doses from external irradiation ranged from 4.9 × 10 Gy to 0.58 Gy (arithmetic mean (AM) dose was 0.048 Gy, median dose was 0.023 Gy), internal thyroid doses from ingestion of I, Te+I, I and I ranged from 0 to 13.3 Gy (AM: 0.34 Gy, median: 0.062 Gy), and internal thyroid doses from inhalation of I, Te+I, I and I ranged from 0 to 0.28 Gy (AM: 0.046 Gy, median: 2.8 × 10 Gy). The AM of thyroid doses from all exposure pathways was 0.43 Gy (range from 3.5 × 10 Gy to 13.7 Gy) and the median was 0.13 Gy. The highest thyroid doses were received by cohort members after test #2 conducted on 24 September 1951 (AM: 1.1 Gy, geometric mean (GM): 0.70 Gy), followed by test #1 conducted on 29 August 1949 (AM: 0.49 Gy, GM: 0.047 Gy) and the thermonuclear test #4 conducted on 12 August 1953 (AM: 0.16 Gy, GM: 0.14 Gy). The predominant pathway of thyroid exposure in the cohort was intake of I with fresh milk from mares and cows, and dairy products made from these types of milk. Although the uncertainties in the dose estimates were not quantified, it was estimated that they are characterized by a geometric standard deviation from 2.0 to 4.0 for most individuals. The study cohort received quite high thyroid doses compared to other populations exposed to fallout from the Chernobyl accident and atmospheric nuclear weapons tests conducted elsewhere. The cohort included individuals exposed in utero, as children and as adolescents to high doses of radiation to the thyroid gland. Consequently, it provides a unique opportunity to assess radiation-related risks of thyroid cancer, thyroid nodules, and other structural and functional non-cancer thyroid diseases.

Reliable and accurate radon diagnostics in buildings with elevated radon levels are crucial for selecting the most effective mitigation strategies. Traditionally, such diagnostics relied on passive integrating detectors paired with continuous radon monitors (CRMs), which offer time-resolved and detailed insights into radon fluctuations. However, the historically high cost of CRMs significantly limited widespread deployment. Recent advancements in digital electronics have made various low-cost CRMs such as Corentium Pro and Radonye + 2-broadly available. Although recent scientific studies have thoroughly assessed the performance of these detectors under controlled conditions, their effectiveness in real-world radon diagnostics is not yet well documented. The study aimed to evaluate the applicability of two types of low-cost CRMs - Corentium Pro and RadonEye + 2 - for radon diagnostic evaluation of a residential building. Radon levels were monitored in designated areas of the home across three separate measurement campaigns. To support comprehensive analysis, additional data were collected, including air exchange rates measured via tracer gas techniques, grab samples from indoors leaks and soil gas, and concurrent monitoring of meteorological conditions. Radon concentration measurements obtained from the different methods were in good agreement. Time-series analyses revealed a strong correlation between indoor radon levels and the temperature difference between the indoor and outdoor environments. Furthermore, measurements of air-exchange rates were instrumental in pinpointing the primary radon entry pathways, enabling the design of more effective remediation strategies.

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, 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.

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 V 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.

Explicit standards for buildup-bolus applications in post-mastectomy radiotherapy remain unclear. This study aimed to perform a dosimetric evaluation of target volumes and organs at risk associated with various buildup-bolus thicknesses and application frequencies to identify the optimal buildup-bolus regimen. Thirty-eight post-mastectomy patients were randomly selected between 2017 and 2024. Four sets of simulated treatment plans were created using virtual buildup-boluses with different protocols: daily 3-mm-thick, daily 5-mm-thick, half-time 5-mm-thick, and half-time 10-mm-thick. Cumulative dose-volume histograms were generated for each buildup-bolus regimen to assess dosimetric differences in target volumes and organs at risk. Equivalent uniform dose and normal tissue complication probability were evaluated for the skin. In terms of target volumes, the daily 5-mm-thick buildup-bolus regimen could reduce hot-spot doses while ensuring adequate target dose coverage, and improved dose homogeneity and conformity; For organs at risk, it could deliver necessary chest wall dose while minimizing high-dose exposure to the skin. Radiobiological evaluation of the skin indicated that the daily 5-mm-thick buildup-bolus regimen could reduce recurrence risk. Additionally, this regimen required the fewest monitor units, thereby reducing treatment time and alleviating machine wear and tear. It is concluded that the daily 5-mm-thick buildup-bolus regimen represented the optimal balance for target coverage and chest-wall skin sparing. These findings provide clinical guidance for treatment planning in post-mastectomy radiotherapy.

Previously published data on ratios of absorbed dose in thermoluminescence dosimeters (TLD) placed inside brick walls to dose in brick material were revisited and analysed. It is shown that for certain TLD setups the dose ratio, determined for monoenergetic radiation sources and averaged over realistic photon spectra, significantly differs from the ratio of average doses in TLD and brick independently calculated for the same photon spectrum. For natural and anthropogenic radionuclides, the difference is approximately 10-15% for Al-coated TLD and 20-30% for Cu-coated ones. The spectrum-averaged ratio is recognised as an approximation and, therefore, its use is discouraged, so the new data provided here are meant to supersede those previously published.

In 1994, the United States and the Russian Federation signed an agreement to cooperate in research on radiation effects, establishing the Joint Coordinating Committee for Radiation Effects Research (JCCRER). Over the past 30 years, the JCCRER has focused on understanding the health effects of chronic radiation exposure, particularly in the Mayak Production Association facilities and surrounding areas. The research has led to significant advancements in radiation protection, with projects categorized into public exposures and effects, and worker exposures and effects. Key projects include dose reconstruction, cancer risk estimation, and the development of dosimetry models. The collaboration has resulted in numerous scientific publications and has set a precedent for future international scientific partnerships. This article summarizes the intent and results of each of the projects performed under the JCCRER over the past 3 decades.

Simulating catastrophic events and modeling ecological impacts are essential for supporting nuclear safety regulations and informed environmental decision-making. This study uses the HotSpot Health Physics and ERICA software tools to evaluate the ecological consequences associated with a hypothetical release of the core inventory from a small modular nuclear reactor (SMR). By integrating these computational tools, the influence of atmospheric stability on radiological contamination and exposure to biota was investigated. The findings obtained suggest that non-human reference organisms can be used as proxies to evaluate ecological exposure, supporting screening-level assessments of environmental contamination. All modeled organisms are categorized within the terrestrial ecosystem category specified in the ERICA tool, enabling broad comparisons of radiological consequences across different ecological groups. The consequences for terrestrial, aquatic, and aerial organisms vary significantly based on Pasquill-Gifford (PG) stability classes, emphasizing the necessity for species-specific safety protocols. Among the modeled terrestrial organisms, burrowing mammals showed greater variability in exposure levels under different atmospheric stability conditions, while flying insects and mollusks exhibited more consistent dose estimates. By recognizing contamination patterns that depend on ecological contexts, policymakers can refine nuclear safety guidelines to mitigate long-term environmental impacts. These findings may guide crisis response strategies by integrating ecological factors into overall frameworks for management of radiological consequences. Ultimately, the findings highlight the importance of incorporating environmental consequence modeling assessments into nuclear regulatory frameworks to improve the protection of biodiversity while enhancing human safety measures.