National Institutes for Quantum and Radiological Science and Technology
National Institute of Radiological Science: NIRS-Repository / 放射線医学総合研究所 学術機関リポジトリNot a member yet
37195 research outputs found
Sort by
Self-Assembled Fluorescent Nanodiamond Layers for Quantum Imaging
No full textThe nitrogen-vacancy (NV) center in diamond is emerging as a powerful tool for imaging magnetic and electric signals at the microscale and below. However, most imaging demonstrations thus far have relied on costly, millimeter-sized bulk diamond substrates, which cannot be easily scaled or integrated with other materials. Here, we report a scalable method for fabricating NV- containing dense and homogenous fluorescent nanodiamond (FND) layers through electrostatic self assembly and demonstrate the utility of the FND layers for magnetic imaging. We investigate the effect of FND concentration in suspension, substrate immersion time, and solvent pH on the FND density on the substrate. We identify optimized self-assembly conditions that maximize the FND density while minimizing aggregation. Using FND layers on a quartz substrate, we demonstrate magneticfield and magnetic noise imaging at the microscale, based on NV optically detected magnetic resonance magnetometry and T1 relaxometry, respectively. Our results provide a direction for the development of cost-effective and scalable FND layers and surface coatings. This paves the way for on-demand quantum sensing and imaging on a broad range of surfaces based on NV centers and other diamond quantum emitters.journal articl
タウ病態の分子的・空間的側面を模倣した新規タウオパチーモデルの開発と応用
No full text認知症研究において、モデル動物を用いた基礎研究は病態の理解、PET薬剤の開発において非常に重要である。しかし、既存のモデル動物には遺伝子工学上の欠点が存在し、ヒト病態を正しく反映していない可能性が指摘されている。それら問題点を克服するべく、我々が作成した次世代型モデルマウスについて得られた研究成果を発表する。AMEDムーンショット型事業 樋口班 「グリア病態からセノインフラメーションへの発展する概念に基づく認知症発症機序の早期検出と制御」 第1回 若手の会conference presentatio
Ligand binding to the membrane-distal domain of Met receptor induces dimerization at the membrane-proximal domain
No full textActivation of cytokine and growth factor receptors by ligands triggers crucial cellular responses in various physiological processes. However, our understanding of their structural basis remains incomplete due to the limited information on the active ligand–receptor complex structure. Their structural analysis poses two significant challenges: preserving the complex structure during isolation from living cells and achieving high-resolution characterization. In this study, we analyzed the structure of the active complex of the hepatocyte growth factor (HGF)-Met receptor by chemically fixing prior to isolating from living cells and high-speed atomic force microscopy imaging at the single-protein level. We also conducted split-luciferase complementary assay and cryo-electron microscopy experiments for the HGF-Met extracellular domain complex and complemented these results with molecular dynamics simulations. We found that HGF binding to the Sema domain of Met promotes homotypic dimerization at the membrane-proximal region of Met, specifically the IPT4 domain. In summary, our study unveils the structural features of the physiological HGF-Met complex and clarifies the ligand-induced dimerization of the Met receptor.journal articl
Effects of Electron-Hole Pair Excitations on Kα X-ray Emission Spectra in 3d Transition Metals
No full textWe theoretically investigate the influence of electron-hole pair excitations on Kα X-ray emission spectroscopy (XES) in 3d transition metals (TMs) from Cr to Cu. Utilizing Keldysh Green’s function method for nonequilibrium states, we calculated the Kα XES spectra for nonmagnetic and (anti)ferromagnetic 3d TMs. We applied the lowest-order Born and local random-phase approximations to incorporate the effects of electron-hole pair excitations on XES spectral shapes. Our results reveal that electron-hole bound states notably modify the Kα XES spectral profiles of 3d TMs. Moreover, shoulder and satellite peaks appear on the low-energy side of the Kα peaks for Cr, Mn, and Fe.Considering these bound states, we can obtain a trend in the asymmetry index that aligns well with experimental findings. This study shows that accurately predicting Kα XES for 3d TMs requires detailed treatment of the magnetic state and 3d electron-hole pair excitations.journal articl
Application of the Avrami-Dobrzyński model for mammary tumorigenesis in irradiated rats indicates new candidates for parametric cancer risk assessment
No full textThe two-parametric Avrami-Dobrzyński model, originally based on the condensed matter physics for phase transitions, was applied to the cumulative populational mammary cancer data of laboratory rats. The joint effect of parity, irradiation and BRCA1 mutation on breast cancer incidence was analysed. The study showed that the proposed model fits well with the data points, however, the values of parameters differ regarding the investigated group of animals. It was concluded that both model’s parameters, which relate to the dimension of carcinogenesis dynamics and the age distribution, are good candidates for cancer risk assessment regarding different risk factors.journal articl
High-Fat Diet and Altered Radiation Response
No full textHigh-fat diets (HFDs) are becoming increasingly prevalent and are a major contributor to the rising incidence of obesity and metabolic disorders, including diabetes and heart disease. At the same time, exposure to ionizing radiation (IR) from medical procedures, environmental sources, and occupational settings remains a significant public concern. This review explores the interplay between HFDs and IR, focusing on their combined effects on metabolism, immune function, and DNA repair mechanisms. We found that HFDs can exacerbate radiation-induced damage by increasing oxidative stress, inflammation, and DNA damage, potentially elevating the risk of chronic diseases. Surprisingly, in some cases, HFDs also trigger cellular changes that reduce the efficacy of radiation therapy in cancer treatment. Furthermore, maternal HFD exposure can increase radiation sensitivity in offspring, particularly males, by disrupting immune and metabolic functions. Understanding the influence of diet on radiation response is crucial for developing effective public health strategies. The timing and composition of dietary intake in the context of radiation exposure are key considerations for optimizing public health interventions, improving cancer treatment outcomes, and minimizing radiation-related health risks. We encourage collaborative dietary and lifestyle interventions aimed at reducing chronic disease risk and enhancing health outcomes, particularly among vulnerable populations. This review provides evidence to guide such efforts toward improved health and therapeutic outcomes.journal articl
Fibroblast Activation Protein Targeting Radiopharmaceuticals: From Drug Design to Clinical Translation
No full textThe activation proteins released by fibroblasts in the tumor microenvironment regulate tumor growth, migration, and treatment response, thereby influencing tumor progression and therapeutic outcomes. Owing to the proliferation and metastasis of tumors, fibroblast activation protein (FAP) is typically highly expressed in the tumor stroma, whereas it is nearly absent in adult normal tissues and benign lesions, making it an attractive target for precision medicine. Radiolabeled agents targeting FAP have the potential for targeted cancer diagnosis and therapy. This comprehensive review aims to describe the evolution of FAPI-based radiopharmaceuticals and their structural optimization. Within its scope, this review summarizes the advances in the use of radiolabeled small molecule inhibitors for tumor imaging and therapy as well as the modification strategies for FAPIs, combined with insights from structure-activity relationships and clinical studies, providing a valuable perspective for radiopharmaceutical clinical development and application.journal articl
Desorption of cesium from Fukushima soils using a mechanochemical(MC) method
No full textPlease insert here a statement of the problem that motivated your study. Follow that statement with a statement of your objective in terms of what was measured or determined.] The Fukushima Daiichi Nuclear Power Plant accident caused severe soil contamination by radioactive cesium (Cs). The large volume of removed soil from decontamination must be disposed of by 2045, requiring volume reduction. However, Cs is strongly adsorbed onto clay minerals in the soil, making removal difficult. Thus, the desorption behavior of Cs adsorbed onto weathered biotite (WB), a clay mineral abundant in Fukushima soils, was investigated using a mechanochemical (MC) method which combines physical grinding by ball impact and friction with a wet process that promotes chemical reaction. The results, oxalic acid desorbed Cs to some extent without significantly affecting the layered structure of the clay minerals and ammonium chloride showed an exfoliation and an ion-exchange effect the layer structure, resulting in a similar level of desorption. The MC method using ammonium chloride solution desorbed ~73% of the stable Cs from WB samples and 80% of 137Cs from soil collected in Fukushima, and the desorption behavior was reliably reproduced in actual soil samples. In contrast, oxalic acid did not always result in high ¹³⁷Cs desorption. Based on these findings, the desorption behavior of Cs indicated that the MC method acts effectively promotes radioactive Cs desorption which has been adsorbed strongly on the interlayer due to the synergistic effect of the chemical effect of the ammonium chloride solution and the physical impact of exfoliation and pulverization of the layered structure. This method, therefore, should reduce the volume of remove soil requiring final disposal, thereby lowering associated management costs.journal articl
Global crystal identification of light-sharing PET detectors using convolutional neural networks
No full textIn light-sharing positron emission tomography (PET) detectors, Anger logic enables identification of crystals smaller than the photodetector size. This approach, which employs a 2D position histogram and pixel-to-crystal mapping, is widely adopted due to its hardware implementation simplicity. In contrast, independent readout systems allow interaction detection using light distribution analysis via photodetector arrays, as each photodetector collects signals independently. Both approaches require detector-specific recalibration during manufacturing, maintenance, and replacement. In this work, we develop a PET scanner-wide crystal identifier using convolutional neural networks (CNNs). Using independent photodetector signals obtained experimentally, the CNN processes crystal addresses derived via Anger logic as training data. When applied to a small animal PET scanner with 126 light-sharing PET detectors, the model is trained using 5 million events from only 40 detectors after denoising, which particularly includes removal of inter-crystal scattering (ICS). By learning light distribution, the CNN also operates as an ICS identifier that sets thresholds to suppress ICS events. With 98 % accuracy in photoelectric absorption events, we confirm a small rod phantom, validated to have similar timing and imaging performance as for Anger logic, provides a 1.7-fold improvement in sensitivity. This CNN-based crystal identifier eliminates the need for recalibration while maintaining image quality and offering applications in maintenance, replacement, and mass production.journal articl
超高強度J-KAREN-Pレーザーシステムと利用研究におけるデジタル化
No full textThe Kansai Institute for Photon Science (KPSI) of the National Institutes for Quantum Science and Technology (QST) has developed an ultra-high-intensity laser system (named the J-KAREN-P laser system) with petawatt-class (PW=1015 W) laser pulses at a repetition rate of 0.1 Hz. A digital transformation (DX) is underway to make the J-KAREN-P laser system available to more users. We are focusing on automating control, enabling remote operation, and visualizing laser processes. These upgrades have not only improved the convenience of the laser but have also expanded the amount of time the laser can be used per day. Furthermore, we plan to introduce Artificial Intelligence (AI) into the J-KAREN-P laser system to enhance automatic operation and detect damage in the optical components and so on.journal articl