Earticle

Background: Accidents involving radiographic exposure occur worldwide. During inspection, a large amount of X-ray exposure occurs when the operator is near the source. Therefore, understanding the amount of radiation exposure that can occur in an accident during X-ray work is important. Materials and Methods: X-ray spectra of an X-ray computed tomography (CT) system were measured at 50, 100, and 200 kV. Gafchromic film external beam therapy 4 (EBT4) was used to measure direct X-rays from the Be window of the X-ray CT. Directed and scattered X-ray doses were evaluated using a thermoluminescent dosimeter (TLD-100H) (Thermo Fisher Scientific Inc.). Results and Discussion: Characteristic L-X-ray emitted from the tungsten filament of an X-ray CT machine were observed at 8–10 keV in an open-tube X-ray CT system without a metal filter. The dose rate of personal dose equivalent at a depth of 0.07 mm (Hp(0.07)) was 2.0 Sv/min at 3.7 cm from the X-ray source. The results of Hp(10) for the direct and scattered X-rays showed that the maximum was 7.5 mSv/min. Conclusion: It is important to note that exposure levels can become extremely high if work is performed near an X-ray source without realizing that X-rays are being emitted. We recommend the use of interlock functions and alarm-type personal dosimeters to prevent accidental exposure.

Background: The efficacy of lead-equivalent shielding in modern photon-counting computed tomography (PCCT) for adult brain imaging remains under debate and therefore requires quantitative evaluation under controlled conditions. This study aimed to quantify the radiation dose reduction to out-of-field radiosensitive organs and the effective dose (E) achievable using supplementary lead shielding during adult brain PCCT, employing a polymethylmethacrylate (PMMA) anthropomorphic phantom. Materials and Methods: A PMMA phantom was scanned using a first-generation PCCT system with a standard adult brain protocol under two conditions: unshielded and shielded. Shielding consisted of a 0.5 mm lead-equivalent neck collar and apron, which were applied after scout acquisition. Organ equivalent doses were measured at 55 anatomical sites using thermoluminescent dosimeters. The E was calculated using tissue weighting factors from International Commission on Radiological Protection (ICRP) Publication 103 and was compared with doselength product (DLP)-based estimates. Results and Discussion: Lead shielding resulted in statistically significant dose reductions (all false discovery rate-adjusted q<0.05) in multiple out-of-field organs, including the breast (83.3%), esophagus (88.5%), lungs (85.2%), and thyroid (44.5%). The overall E was reduced by 8.7%, from 2.98 mSv to 2.72 mSv. A substantial methodological discrepancy was observed, as DLPbased E estimates were 47%–52% lower than those derived from phantom measurements using ICRP Publication 103. Conclusion: This phantom study demonstrates that lead-equivalent shielding can significantly reduce radiation dose to out-of-field organs during adult brain PCCT. However, achieving this benefit is critically dependent on proper procedural implementation. Shielding must be applied after scout (localizer) acquisition to avoid interference with the scanner’s automatic exposure control system. The marked discrepancy between dose estimation methods indicates that DLPbased values, while useful for population-level benchmarking, have inherent limitations for precise, protocol-specific optimization. These findings support the targeted and protocol-appropriate use of shielding for vulnerable patients, in accordance with the As Low As Reasonably Achievable (ALARA) principle.

Background: The health risks associated with radon exposure have been known for decades. European legislation has established basic safety requirements for protection against hazards arising from exposure to indoor radon. European Union (EU) Member States are required to implement national radon action plans to address the long-term risks of radon exposure in homes, public buildings, and workplaces. Materials and Methods: By applying the drivers, pressures, state, impact, and response model (DPSIR) to radon and incorporating key factors associated with European legislation into the causal framework, indicators were identified to assess the effectiveness of the actions implemented by national radon action plans in line with EU guidelines. Results and Discussion: Since national radon action plans must take into account aspects such as radiation protection, geology, epidemiology, data management and analysis, political responsibility, building construction techniques, and communication, an extensive set of 25 effectiveness indicators associated with specific objectives of European radon legislation has been identified. It would be difficult for a policy maker to guide decisions among so many different indicators, so a core set of four effectiveness indicators has been selected based on the political relevance, analytical validity, and measurability of each indicator. Conclusion: Despite the critical issues highlighted, these indicators represent the key elements of a national radon action plan in line with the European Basic Safety Standards (EU-BSS) and describe the effectiveness of primary responses in terms of potential improvements in the country’s situation.

Background: Absolute light yield measurement based on single photoelectron (SPE) approach remain susceptible to random coincidences between pulsed excitation trigger and the photomultiplier tube (PMT) response. Few studies have reported a quantitative comparison of SPE-based light-yield estimation before and after random-coincidence suppression. To address this, we developed a simplified digitizer-based setup to quantify the light yield using a predefined time window to suppress random-coincidence events. Materials and Methods: SPE spectra were measured by stimulating a PMT with a dim light emitting diode, and the anode signals were recorded using a high-speed digitizer. Event timestamps were used to select correlated signals within the time window. A 2.54 cm×2.54 cm (1˝×1˝) CsI(Tl) scintillator was sequentially coupled to R2228 and R1924A PMTs under identical configurations to verify the consistency of the measured light yield across the two PMTs. Results and Discussion: Suppressing random coincidences eliminated bias in SPE estimation, which otherwise led to an ~11% overestimation in light yield. The CsI(Tl) light yield was determined as 50,000±2,000 photons/MeV and 51,000±2,000 photons/MeV for R2228 and R1924A PMT, respectively. This digitizer-based SPE approach provides a reliable and reproducible method for light yield measurement. Conclusion: We demonstrated a simplified digitizer-based SPE measurement method, applying a time-window filter to reject random coincidence events. This approach enables accurate estimation of the SPE charge and, consequently, a reliable and reproducible light yield evaluation, which have been confirmed with consistent results obtained by the two PMTs.

Background: Ionizing radiation for medical diagnosis and therapy can have negative health effects on service providers. In this study, we investigated the radiation safety awareness of healthcare professionals who work mainly with ionizing radiation. Materials and Methods: Workers in the diagnostic radiology, clinical oncology, and nuclear medicine departments of 11 hospitals in two cities in Türkiye (n=203) responded to a questionnaire that was specially designed to measure their knowledge and awareness about aspects of ionizing radiation and protection measures. Results and Discussion: Although the respondents’ primary role was directly related to ionizing radiation, results indicated that some had a knowledge gap about radiation safety and that the gap increased with the increase in age of the respondents. A Kuder–Richardson Formula 20 test for the dichotomized variables revealed an internal consistency of 0.83, indicating the validity of the results. Conclusion: Lack of ionizing radiation safety awareness among many healthcare workers who deal with radiation on a daily basis might put their own safety and the safety of patients at risk. Recommendations specific to the observed awareness gaps are suggested, including adjusting university program curricula and providing additional training to current employees to increase knowledge and awareness.

Background: Precision medicine aims to optimize therapeutic efficacy and minimize adverse effects by addressing individual biological variability. In radiotherapy, assessing radiation sensitivity is crucial for clinical safety and radiation protection. Recently, patient-derived organoids have emerged as pivotal preclinical models for evaluating personalized radiation responses. Materials and Methods: This study analyzed global patent filings (2005–2025) related to organoid- based radiation sensitivity diagnostics. Patents were systematically classified by country, technology group, and applicant type. After screening and refining 5,097 patents, the final dataset included a total of 1,074 valid patent families. Quantitative analyses were performed to characterize temporal trends, developmental stages, and competitive structures across different regions. Results and Discussion: The global patent landscape has exhibited a robust upward trajectory with a compound annual growth rate of 11.9% from 2005 to 2025. China and South Korea are exhibiting significant recent growth, with the annual filings peaking at 136 in 2023. Technology groups focused on organoid culture/fabrication and radiation sensitivity prediction account for nearly 80% of the total portfolio. A distinct developmental asymmetry was observed: industrial applicants primarily drive culture-related technologies toward commercialization, whereas hospitals and research centers lead sensitivity prediction, reflecting a decisive shift toward clinically oriented, data-driven research. Conclusion: This systematic analysis characterizes the structural and competitive dynamics of organoid-based radiation diagnostics. The findings serve as a strategic baseline for stakeholders to navigate future research trajectories and formulate intellectual property strategies in the field of precision radiation medicine.

The system of radiological protection developed by the International Commission on Radiological Protection (ICRP) provides the scientific and conceptual basis for regulatory frameworks worldwide, including that of Japan. Following the publication of the 2007 Recommendations (ICRP Publication 103), the system has continued to evolve in response to advances in scientific knowledge and changes in societal values. Recent international discussions, particularly those associated with the 7th International Symposium on the System of Radiological Protection (ICRP 2023), have highlighted the potential need for revisions to the existing framework and the introduction of new concepts. In this context, the Nuclear Regulation Authority of Japan commissioned a series of projects in fiscal years 2024 and 2025 to systematically review ongoing ICRP activities and to assess their potential impacts on the Japanese regulatory framework. This paper provides an overview of these projects and their key findings. Information from relevant ICRP task groups was collected and organized into seven thematic areas: (1) overarching theme on the system of radiological protection; (2) radiation detriment and classification of effects; (3) impacts of a new dose assessment system; (4) radiological protection of the environment; (5) reasonableness, tolerability, and justification; (6) exposure situations and exposure categories; and (7) individualization and stratification in radiological protection. A detailed investigation conducted in fiscal year 2025 focused on the impacts of a new dose assessment system. The results highlight the importance of clearly distinguishing between technical changes, which can be addressed through incremental regulatory revisions, and conceptual changes, which may require substantial amendments to existing laws and regulatory structures. The findings underscore the need for continuous monitoring of international developments and proactive nationallevel discussion