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The Japanese Journal of Health Physics has published many articles related to the 2011 accident at Tokyo Electric Power Company’s Fukushima Daiichi Nuclear Power Station. Among them, as of March 2022, 39 articles in the field of environmental monitoring had been published. These articles cover a wide range of topics, including environmental radiation, radioactivity monitoring, and decontamination methods developed after the accident. The papers presented in this journal and reviewed in this article reflect the experiences of experts in radiation protection and radioecology, and they also serve as a record of the practical challenges faced at the time. Readers are encouraged to use this review as a gateway to the original articles.

Microdosimetry does not simply refer to dosimetry with small targets, but rather to dosimetry that accounts for the stochastic nature of energy deposition. The International Commission on Radiation Units and Measurements has proposed using the probability densities of microdosimetric quantities such as lineal energy (y) and specific energy (z) to characterize the radiation fields instead of relying solely on linear energy transfer (LET) and absorbed dose. However, the practical application of microdosimetry remains limited due to significant computational costs associated with evaluating these stochastic quantities in macroscopic contexts such as the human body. To bridge the gap between microdosimetry and macrodosimetry, three approaches have been proposed and implemented: direct integration of track-structure and macroscopic radiation transport codes; integration of a database containing dose-mean values of microdosimetric quantities into macroscopic radiation transport codes; and integration of the analytical microdosimetric function for instantaneously calculating the probability densities of microdosimetric quantities within macroscopic radiation transport codes. This paper comprehensively reviews the conceptual and practical differences between LET and microdosimetric quantities, including their respective computational methodologies. The advantages and limitations of the three approaches are then discussed, followed by a summary of previous research efforts and suggestions for future research directions.

Background: Radiation plays a vital role in medical diagnosis and treatment. However, insufficient radiation protection education poses serious risks to patients and healthcare professionals. Nursing students often have limited formal training, and traditional lecture-based methods foster passive learning, which may not promote deep understanding. Augmented reality (AR) technology offers a novel approach by overlaying digital models onto real-world images, enabling students to intuitively visualize abstract concepts such as time, distance, and shielding. This study was conducted to evaluate an AR-based radiation protection application integrated with conventional lectures to enhance the knowledge of nursing students and calibrate their perceptions of radiation safety. Materials and Methods: A cross-sectional, pre–post-intervention study was conducted at Tokyo Metropolitan University among 80 second-year nursing students (95% female) without prior radiation safety training. The intervention comprised two phases: a standardized 90-minute lecture covering the nature and biological effects of ionizing radiation and the principles of time, distance, and shielding; and a hands-on AR session using an Android-based application that overlays a three-dimensional model of scattered radiation dose onto a live camera view, demonstrating exposure effects. Radiation knowledge was assessed using a 50-item questionnaire, and risk perception was measured using a 30-item, seven-point Likert scale. Data in this study were analyzed using nonparametric tests and compared with reference data. Results and Discussion: Post-intervention knowledge scores were significantly higher than pre-intervention and reference scores (p<0.05). Additionally, risk perception ratings for ‘nuclear power’ and ‘X-ray’ decreased by one rank, suggesting a more balanced and realistic evaluation of risks. Conclusion: Integrating AR with traditional lectures significantly improves radiation protection knowledge and risk assessment among nursing students, supporting the promising role of AR in healthcare education. Future research should include longitudinal follow-up and explore AR features, such as dose simulation.

Background: The Kaligandaki River from Kushma to Galeshwor is considered a high natural background radiation area, requiring baseline assessment of naturally occurring radionuclides for radiation protection. Materials and Methods: A portable gamma-ray spectrometer (PGIS-2) equipped with a NaI(Tl) scintillator detector was employed. Radiological hazard parameters, including radium equivalent activity, absorbed gamma dose rates in air, annual effective dose rate, external hazard index, and internal hazard index, were determined. Results and Discussion: The mean activities of radionuclides 238U, 232Th, and 40K, were found to exceed global average values. Radium equivalent activity ranged from 141.48 Bq·kg−1 to 313.24 Bq·kg−1, with a mean value 204.91 Bq·kg−1 for the Kushma–Galeshwor region. The annual effective dose rates were 0.12 mSv· yr−1 and 0.47 mSv· yr−1 for outdoors and indoors, respectively. Conclusion: Although these values exceed global averages, they remain within established safety limits. The findings highlight the importance of continuous monitoring to ensure environmental and public safety in regions with naturally occurring radioactive materials. Therefore, from a radiation protection perspective, the region is considered safe.

Background: We aimed to evaluate the effects of different incident directions on organ-absorbed doses, effective doses, and effective dose conversion coefficients for chest radiography. Materials and Methods: We constructed an examination environment for chest radiography using a Monte Carlo simulation and estimated the organ-absorbed doses and effective doses for frontal anterior–posterior (AP), frontal posterior–anterior (PA), left lateral, and right lateral radiography. The effective dose conversion coefficients were calculated using the air kerma-area product. Results and Discussion: Some organs, such as the breast, showed more than a fivefold difference in the organ-absorbed dose between AP and PA radiography. In lateral radiography, there was a large difference in the organ-absorbed doses in the abdominal region. The effective dose was approximately 30% higher for AP radiography than for PA radiography. The effective dose conversion coefficients differed between AP and PA radiography. These findings are consistent with the anatomical arrangement of organs in the human body; nevertheless, they have not been explicitly reported in previous studies. Conclusion: It was suggested that using the PA direction of incidence in frontal radiography reduces the effective dose received by the patient. In addition, when estimating the effective dose using conversion coefficients, the estimated value may differ significantly due to differences in the direction of incidence, so the coefficients must be appropriately selected.

Background: Healthcare workers’ radiation safety during fluoroscopy-guided procedures remains a critical occupational health concern, particularly for nursing staff with intermittent exposure. With evolving healthcare practices, increasing procedural volumes, and technological advancements in fluoroscopic equipment, there is a need to evaluate whether continuous personal radiation dose monitoring is necessary for occasionally exposed nursing staff in operating rooms and endoscopy suites. Materials and Methods: A prospective observational study was conducted at a Singapore public hospital from July to December 2024. Eighty nurses from operating theatre and endoscopy departments were equipped with a personal dosimeter to record their dose exposure. A secure digital platform with QR code integration enabled immediate exposure logging via participants’ mobile phones, capturing 1,512 exposure data from various procedures. Radiation doses were measured bimonthly by Singapore’s National Environment Agency. Results and Discussion: Analysis revealed significant variations in the median of total exposure time across specialties, with participants specializing in vascular having the highest median exposure (4.4 hours), followed by endoscopy (2.8 hours), urology (0.3 hours), and orthopedics (0.2 hours). Despite these variations, total effective doses remained consistently low across participants from all specialties below the study period threshold of 1 mSv. The absence of a strong correlation between exposure time and effective dose suggests the effectiveness of current radiation protection measures. Cost-benefit analysis indicated potential savings of approximately $60,000 annually through reduced subscription fees, in addition to administrative man-hour savings, which would have been required for dosimeter management and dose reporting for a cohort of 315 staff. Conclusion: This study demonstrates that occasional participation in fluoroscopy-guided procedures results in minimal radiation exposure for nursing staff, supporting the discontinuation of routine radiation monitoring while maintaining periodic reviews. The findings demonstrate that current radiation protection protocols effectively maintain exposure levels well within safety limits.