Publications by authors named "Osamu Kurihara"
We investigated the neutron dose estimation for the triage of personnel involved in criticality accidents by conducting 24Na measurements via the whole-body measurement method. For a case study, we examined the September 1999 Japan Nuclear Fuel Conversion Co. criticality accident (internationally known as "the Tokaimura accident").
View Article and Find Full Text PDFAn attempt was made to estimate organ doses of a victim in a high-dose non-homogeneous exposure accident caused by a sealed 192Ir gamma-ray source. The Gilan accident was selected as a case study. Organ doses including testis, red bone marrow and so on were properly estimated by applying the Monte Carlo calculation with the state-of-the-art adult male Mesh type Reference Computational Phantom.
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- Febuxostat is effective for treating severe hyperuricemia in chronic kidney disease (CKD), and combining it with uricosuric agents like dotinurad may further lower uric acid levels.
- A study of 34 CKD patients showed that adding dotinurad to febuxostat increased uric acid excretion and reduced serum uric acid levels in patients with moderate kidney impairment (G3 and G4) but not in those with severe impairment (G5).
- The research highlights the need for further exploration of dotinurad's mechanisms to understand its role in managing uric acid levels in CKD patients.
Article Synopsis
- This study explores a new, simpler method for alpha spectroscopy that allows radionuclidic purity tests at 225Ac production sites without needing a vacuum chamber.
- It focuses on improving energy resolution using a collimator, achieving results where alpha particles from 241Am had a full width at tenth maximum (FWTM) of less than 300 keV.
- The method is validated experimentally, effectively separating alpha peaks from different isotopes, and is poised to address the rising demand for targeted radioisotope therapy, particularly in detecting 226Ra mixed with 225Ac.
Article Synopsis
- - The study compares the old and new lung counters at Japan's National Institutes for Quantum Sciences and Technology, noting the new counter has a ~15% smaller sensitive area in its detector crystals.
- - Minimum detectable activities (MDAs) for the radioactive isotopes 241Am and 239Pu were measured using a torso phantom, revealing similar detection capabilities for both counters despite the differences in design.
- - For a chest wall thickness of 2.1 cm and a counting time of 30 minutes, the MDAs were slightly lower for the new counter compared to the old one, and it provided improved measurement geometry for left-side versus right-side detection.
Article Synopsis
- - A study involving 1,840 Japanese patients with acute coronary syndrome (ACS) identified two groups: those who experienced major bleeding and those who did not, over a 2-year follow-up period.
- - Out of the participants, 124 patients (6.7%) had major bleeding, which was linked to a significantly higher rate of cardiovascular deaths (26.4% vs. 8.5%).
- - Analysis through optical coherence tomography revealed that disrupted fibrous cap and calcified plaque were more common in patients who bled, with disrupted fibrous cap being a significant predictor of major bleeding.
Article Synopsis
- - The study investigates the internal radiation doses of residents near the Fukushima Daiichi Nuclear Power Plant following the 2011 accident, using whole-body counter (WBC) measurements to assess exposure to cesium isotopes 134Cs and 137Cs.
- - By expanding research to include residents from four affected towns, the study aims to link individual cesium doses with evacuation behaviors after a major release event on March 12, 2011, particularly focusing on those who delayed evacuation.
- - Key findings indicate significant differences in cesium detection rates between residents who evacuated farther from the plant and those who stayed closer, supporting previous analyses of radiation exposure patterns from the disaster.
In a nuclear emergency, one of the actions taken for the sake of public is to monitor thyroid exposure to radioiodines. Japan's Nuclear Regulation Authority recently published a report on such monitoring and proposed direct thyroid measurements with conventional NaI(Tl) survey meters (e.g.
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- Researchers used gamma-ray spectrometry with a NaI(Tl) scintillation spectrometer to differentiate between natural and man-made radionuclides impacting gamma dose rates in the environment, focusing on the effects of nuclear accidents.
- They discovered that the accuracy of measurements was hindered by low energy resolution, which resulted in an overestimation of ambient gamma doses from natural radionuclides, particularly due to the interference from the radionuclide 134Cs.
- The study found a strong correlation between absorbed dose rates in air and photon fluxes from the radionuclide 208Tl, suggesting it can be effectively used to estimate absorbed dose rates, with specific rates measured in Namie Town and Okuma Town post-Fukushima ranging from
Article Synopsis
- The study investigates the effects of dotinurad, a new drug aimed at lowering uric acid levels, on kidney function in patients with severe renal dysfunction.
- Researchers analyzed data from 53 outpatients with hyperuricemia and found that while serum uric acid levels decreased significantly across all groups, only patients with an estimated glomerular filtration rate (eGFR) below 30 showed significant improvement in kidney function.
- The results suggest that dotinurad might benefit those with severe renal dysfunction by both lowering uric acid and potentially enhancing kidney function, especially in patients with lower baseline eGFR.
Rapid measurement of actinides in urine by mass and alpha spectrometric methods.
Radiat Prot Dosimetry
October 2023
Article Synopsis
- Researchers developed quick methods to test urine for trace actinide isotopes to help make faster decisions in emergency radiation therapy.
- The mass spectrometric method involves complex purification steps using specific resins to measure uranium (U) and plutonium (Pu) isotopes in a 20-ml urine sample.
- The alpha spectrometric method also uses purification techniques to detect isotopes like plutonium (Pu), uranium (U), americium (Am), and curium (Cm) in a larger 500-ml urine sample, and both methods were validated through an intercomparison study in 2020.
Article Synopsis
- Establishing a reliable method for monitoring thyroid exposure after accidental radioiodine intake during a nuclear emergency is challenging due to time constraints.
- The authors proposed a method utilizing conventional NaI(Tl) survey meters for quick identification of those significantly exposed and to assess overall exposure levels in affected populations.
- Screening levels for these meters were determined, showing specific thresholds for various age groups: 0.2 μSv h-1 for children ≤5 years, 0.5 μSv h-1 for ages 10 and 15, and 1.0 μSv h-1 for adults, which can be established within a week following iodine intake.
Article Synopsis
- * Researchers created personalized voxel phantoms from MRI scans of 24 adults to analyze variations in the conversion factor for radioiodine measurement, revealing significant individual differences.
- * Findings indicated that the standard reference Japanese phantoms tend to overestimate radioiodine levels in the thyroid, highlighting the importance of considering individual thyroid volume in dose assessments for those exposed to high radiation.
Accidental inhalation intake of plutonium isotopes and 241Am occurred at a Pu research facility in Japan in 2017, and the five workers involved in this accident were treated by the administration of Ca/Zn-diethylenetriaminepentaacetic acid (DTPA). For the worker who was most internally exposed, the therapy was continued over 1 y after the accident. Urinary samples collected before and after each administration were subject to bioassay to evaluate the efficacy of the dose reduction.
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- Japan's National Institutes for Quantum Science and Technology (QST) became the primary center for radiation emergency medical support in Japan as designated by the Nuclear Regulation Authority (NRA) in 2019.
- To enhance its capabilities, QST constructed a new facility called the Dose Assessment Building for Advanced Radiation Emergency Medicine at its Chiba base in 2020.
- The facility includes an advanced bioassay laboratory and an integrated in vivo counter, enabling it to assess internal radiation doses in 5-10 individuals simultaneously depending on the type of contamination.
Development of a new integrated IN-VIVO counting system at the QST.
Radiat Prot Dosimetry
October 2023
A new in-vivo counting system that functions as both a whole-body counter (WBC) and a lung counter (LC) was developed at the QST to enhance its dose assessment capability. This paper presents an overview of this system and the results of its performance tests. For use of the system as a WBC, three high purity germanium (HPGe) detectors installed in a 20-cm-thick iron shielding chamber are linearly arrayed over a subject lying on the bed, whereas two of the three HPGe detectors are placed over the subject's chest from side to side when using the system as an LC.
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- The study measured the responses of two personal dosemeters (D-shuttle and Dose-i) on five different age-specific phantoms while simulating radiation exposure similar to the Fukushima nuclear accident using a 137Cs source.
- Results showed that while the dosemeter responses shifted based on their position on the phantoms, this shift was minor when contamination was evenly spread, and the responses decreased by about 10% as the body size of the phantoms increased.
- Although there were variations (~17%) in the ambient dose equivalent ratios between the two dosemeters, this was attributed to calibration differences; overall, both dosemeters effectively estimated age-dependent effective doses for radiation exposure.
Article Synopsis
- Outcomes after heart attacks in women are still not great, and understanding the connection between risk factors and artery plaque types is limited.
- A study of 382 women with acute coronary syndrome showed that younger women (<60 years) mostly had plaque erosion, while older women had different plaque characteristics.
- Risk factors like smoking, diabetes, and high cholesterol affect plaque development, indicating that addressing these issues early, especially in young women, could help prevent worsening heart disease as they age.
Article Synopsis
- A national project in Japan, called NEWS, was established in 2014 to study the health effects of radiation on workers involved in the Fukushima disaster response in 2011.
- In 2018, researchers collected blood samples from 62 workers to assess chromosome damage and estimated radiation doses using a specialized assay.
- The results showed that biological dose estimates were significantly higher than measured doses, potentially due to factors like smoking and medical treatments, suggesting that past assessments may have overestimated actual radiation exposure for these workers.
Background: Diagnostic strategies depend on non-standardized workup, and the causes of myocardial infarction with non-obstructive coronary arteries remain unclear for some patients. Intracoronary imaging is recommended for detecting the missed causes by coronary angiography. Myocardial infarction with non-obstructive coronary arteries is a heterogeneous entity; a meta-analysis of myocardial infarction with non-obstructive coronary artery studies demonstrated that all-cause mortality rate at 1 year is 4.
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- - Seven nuclear workers exposed to radionuclides, especially I-131, during the Fukushima accident in March 2011 were evaluated at the National Institute of Radiological Sciences over a 10-year follow-up period.
- - They received estimated thyroid doses ranging from 3.2 to 1.2 × 10 Sv but reported no symptoms of abnormal thyroid function.
- - Despite no immediate health issues or abnormalities detected in tests, ongoing monitoring of their thyroid status is recommended for the future.