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This review is based on articles published in Japanese Journal of Health Physics on “Radiationexposed medical care and waste” related to Tokyo Electric Power Company Incorporated (TEPCO)’s Fukushima Daiichi Nuclear Power Station accident. Here, we have considered three original articles; one technical data, one special article, one 50th anniversary article, one preface, three topics, and two cases of From Japan to the World (J to W). These articles have reported the system and standards that were established after the accident. Moreover, they have summarized rare experiences such as the fumbling response at the time and the evaluation of samples in that disaster. These articles constitute valuable records of the situation.

Background: Cone beam computed tomography (CBCT) is essential for correcting and verifying patient position before radiation therapy. However, it poses additional radiation exposure during CBCT scans. Therefore, this study aimed to evaluate radiological safety for the human body through dose assessment for CBCT. Materials and Methods: For CBCT dose assessment, the depth dose was evaluated using a cheese phantom, and the dose in the orbital area was evaluated using a human body phantom self-fabricated with a three-dimensional printer. Results and Discussion: The evaluation of radiation doses revealed maximum doses of 14.14 mGy and minimum doses of 6.12 mGy for pelvic imaging conditions. For chest imaging conditions, the maximum doses were 4.82 mGy, and the minimum doses were 2.35 mGy. Head imaging conditions showed maximum doses of 1.46 mGy and minimum doses of 0.39 mGy. The eyeball doses using a human body phantom model averaged at 2.11 mGy on the left and 2.19 mGy on the right. The depth dose ranged between 0.39 mGy and 14.14 mGy, depending on the change in depth for each imaging mode, and the average dose in the orbit area using a human body phantom was 2.15 mGy. Conclusion: Based on the experimental results, CBCT did not significantly affect the radiation dose. However, it is important to maintain a minimal radiation dose to optimize radiation protection following the as low as reasonable achievable principle.

Background: As the quantity and complexity of radiological interventions are constantly increasing, gear that offers optimal protection while maintaining mobility and a low weight burden is becoming more important. A newly developed exoskeleton radiation protection system (ERPS) (StemRad MD; StemRad Ltd.) can carry the weight of the shielding. The aim of our study was to analyze initial experience, especially in terms of advantages and disadvantages, with this new ERPS in interventional radiology. Materials and Methods: Forty-six interventions utilizing the ERPS were analyzed. The interventional radiologists completed a 15-question survey evaluating various aspects of the protective system, including weight, mobility, comfort, and radiation protection adequacy. Results and Discussion: In 98% of procedures, interventionalists reported being very satisfied (89%) or slightly satisfied (9%) and would recommend the system to colleagues. The exoskeleton system was rated as 100% comfortable, not too heavy, and did not restrict mobility in 98% of cases. Conclusion: The ERPS is a recommendable alternative to standard lead aprons, providing flexibility, comfort, and effective weight distribution without restricting mobility.

Background: This study focuses on the fabrication and characterization of quasi-hemispherical Cd0.9Zn0.1Te (CZT) detector for gamma-ray spectroscopy applications, aiming to contribute to advancements in radiation measurement and research. Materials and Methods: A CZT ingot was grown using the vertical Bridgman technique, followed by proper fabrication processes including wafering, polishing, chemical etching, electrode deposition, and passivation. Response properties were evaluated under various external bias voltages using gamma-ray sources such as Co-57, Ba-133, and Cs-137. Results and Discussion: The fabricated quasi-hemispherical CZT detector demonstrated sufficient response properties across a wide range of gamma-ray energies, with sufficient energy resolution and peak distinguishability. Higher external bias voltages led to improved performance in terms of energy resolution and peak shape. However, further improvements in defect properties are necessary to enhance detector performance under low bias conditions. Conclusion: This study underscores the efficacy of quasi-hemispherical CZT detector for gamma- ray spectroscopy, providing valuable insights for enhancing their capabilities in radiation research field.