Publications by authors named "Hiroshi Watabe"

Background And Objective: In neuroinflammation, activated astrocytes, called reactive astrocytes, highly express monoamine oxidase B (MAO-B). [F]SMBT-1 is a novel PET tracer developed for imaging neuroinflammation, with highly selective binding to MAO-B. The quantification method for [F]SMBT-1 PET imaging has not been established, although some human studies using [F]SMBT-1 PET imaging have already been conducted.

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Efficient and selective removal of radioactive Strontium (Sr) from nuclear wastewater is a sustainable strategy for nuclear energy development and environmental protection due to its long half-life and high biochemical toxicity. Herein, a novel nanolayered manganese oxide material (NaMnO, Na-NLMO) is proposed and its application for Sr(II) capture in both simulated waste liquid and real natural water systems. Na-NLMO is tailored for Sr(II) adsorption through a simple and rapid solid-phase reaction, which has good chemical stability and a strong affinity for Sr(II) across the pH range of 1 to 8.

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Transarterial radioembolization (TARE) using yttrium-90 (Y)-labeled glass and resin microspheres is an emerging therapeutic technique for hepatocellular carcinoma (HCC). However, the non-biodegradability and rapid settlement of current commercial microspheres might hinder their even distribution and repetitive administration thus causing unsatisfactory therapeutic effects. In this context, novel functional chitosan-based microspheres (CPIs) that can efficiently label Y as a favorable TARE material were developed for the first time by successive grafting poly (glycidyl methacrylate) (PGMA) and iminodiacetic acid (IDA) onto chitosan microspheres (CMs).

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Artificial intelligence (AI) has gained significant attention in various scientific fields due to its ability to process large datasets. In nuclear radiation physics, while AI presents exciting opportunities, it cannot replace physics-based models essential for explaining radiation interactions with matter. To combine the strengths of both, we have developed and open-sourced the Radiation Protection Toolkit for Radioisotopes with Artificial Intelligence (RAPTOR-AI).

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Age-related deterioration in positron emission tomography (PET) systems can be monitored using cross-calibration scans for scanner calibration. This study aimed to evaluate changes in the sensitivity of a PET system over time using routinely collected cross-calibration factor (CCF) measurement data and NEMA sensitivity measurement data acquired at our facility. We used CCF measurement data acquired over eight years, from 2016 to 2023.

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Article Synopsis
  • A dosimeter must be calibrated in a field with energy and dose rates similar to its intended measurement environment, especially in areas like nuclear reactors and radiation therapy where high-energy photons are present.
  • The Japan Atomic Energy Agency and National Metrology Institute of Japan provide high-energy reference fields for testing dosimeters, containing photon energies above several megaelectronvolts.
  • The study assessed the performance of two-cavity ionization chambers in these high-energy fields, confirming their accuracy for air kerma measurements with an acceptable level of uncertainty.
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Bifunctional chelators (BFCs) are vital in the design of effective radiopharmaceuticals, as they are able to bind to both a radiometal ion and a targeting vector. The 3p--NETA or 4-[2-(bis-carboxy-methylamino)-5-(4-nitrophenyl)-entyl])-7-carboxymethyl-[1,4,7]tri-azonan-1-yl acetic acid is a novel and promising BFC, developed for diagnostic and therapeutic purposes. The binding affinity between the BFC and radiometal ion significantly impacts their effectiveness.

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Introduction: Brain positron emission tomography/computed tomography (PET/CT) scans are useful for identifying the cause of dementia by evaluating glucose metabolism in the brain with F-18-fluorodeoxyglucose or Aβ deposition with F-18-florbetaben. However, since imaging time ranges from 10 to 30 minutes, movements during the examination might result in image artifacts, which interfere with diagnosis. To solve this problem, data-driven brain motion correction (DDBMC) techniques are capable of performing motion corrected reconstruction using highly accurate motion estimates with high temporal resolution.

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Protection against ionizing radiations is important in laboratories with radioactive materials and high energy cyclotron beams. The Cyclotron and Radioisotope Center (CYRIC) located in Tohoku University in Miyagi prefecture, Japan and is a well-known nuclear science laboratory with cyclotron beams and substantial number of high activity radioactive materials. Considering this, it is important to perform complete radiation transport computations to ensure the safety of non-occupational and occupational workers.

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Purpose: Information about developed positron emission tomography (PET) tracers and obtained clinical PET images is publicly available in a database. However, findings regarding the kinetic parameters of PET tracers are yet to be summarized. Therefore, in this study, we created an open-access database of central nervous system (CNS) kinetic parameters in the healthy human brain for existing PET tracers (DOCK-PET).

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Article Synopsis
  • A new system was created to simultaneously measure three imaging methods—prompt gamma photons, prompt x-rays, and induced positrons—during proton beam therapy using a phantom model.
  • The imaging setup includes a gamma camera, an x-ray camera, and a dual-head PET system to analyze these modalities under controlled conditions.
  • Results showed that induced positrons had the highest image quality, and the system can provide valuable data for enhancing proton beam shape estimation in therapeutic applications.
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In the medical and nuclear fields, there are environments where exposure to photons with energies above several MeV can result in problems. The National Metrology Institute of Japan has developed a high-energy photon field using a 15 MeV electron beam of a clinical linear accelerator with a copper target and an aluminium filter unit to facilitate dosimeter calibration in terms of air kerma. To determine the air kerma rate, the energy fluence distribution at a reference point was calculated, and both calculations and experiments evaluated the effective energy and spatial dose distribution.

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Acute cardiovascular physical exercise improves cognitive performance, as evidenced by a reduction in reaction time (RT). However, the mechanistic understanding of how this occurs is elusive and has not been rigorously investigated in humans. Here, using positron emission tomography (PET) with [ C]raclopride, in a multi-experiment study we investigated whether acute exercise releases endogenous dopamine (DA) in the brain.

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Previously, we have developed DynamicMC for modeling relative movement of Oak Ridge National Laboratory phantom in a radiation field for the Monte Carlo N-Particle package (Health Physics. 2023,124(4):301-309). Using this software, three-dimensional dose distributions in a phantom irradiated by a certain mono-energetic (Mono E) source can be deduced through its graphical user interface.

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. Prompt x-ray imaging using a low-energy x-ray camera is a promising method for observing a proton beam's shape from outside the subject. Furthermore, imaging of positrons produced by nuclear reactions with protons is a possible method for observing the beam shape.

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The present work reports the theoretical investigation of the scattering of electrons and positrons by the ethane (C2H6) molecule over the energy range 1 eV-1 MeV. The investigation was carried out by taking into account the screening correction arising from a semiclassical analysis of the atomic geometrical overlapping of the scattering observables calculated in the independent atom approximation. The study is presented through the calculations of a broad spectrum of observable quantities, namely differential, integrated elastic, momentum transfer, viscosity, inelastic, grand total, and total ionization cross-sections and the Sherman functions.

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Objective: Genistein is an isoflavone molecule with a high affinity for estrogen receptors (ER), which could lead to the mechanism of selective estrogen receptor modulators (SERMs) in breast cancer. Genistein labeling with technetium-99 can be a new promising strategy for diagnostic breast cancer. In this research, we evaluate the physicochemical characteristics of the [Tc]Tc-genistein complex and describe the optimal labeling method parameters.

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The present work introduces an open-source graphical user interface (GUI) computer program called DynamicMC. The present program has the ability to generate ORNL phantom input script for the Monte Carlo N-Particle (MCNP) package. The relative dynamic movement of the radiation source with respect to the ORNL phantom can be modeled, which essentially resembles the dynamic movement of source-to-target (i.

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The present work introduced a framework to investigate the effectiveness of proton boron fusion therapy (PBFT) at the cellular level. The framework consisted of a cell array generator program coupled with PHITS Monte Carlo package with a dedicated terminal-based code editor that was developed in this work. The framework enabled users to model large cell arrays with normal, all boron, and random boron filled cytoplasm, to investigate the underlying mechanism of PBFT.

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Proton irradiations are highly sensitive to spatial variations, mainly due to their high linear energy transfer (LET) and densely ionizing nature. In realistic clinical applications, the targets of ionizing radiation are inhomogeneous in terms of geometry and chemical composition (i.e.

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The interaction of ionizing radiation with matter is a stochastic process and statistical analysis of such a process would be a crucial step in understanding radioactivity. Geiger-Müller (GM) counter is a widely used radiation detector used in nuclear radiation surveying, which produces counts upon exposure to a radioactive source. There are a variety of multi-purpose software that can be used to perform statistical analysis of measured counts from a GM counter.

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The Monte Carlo (MC) method is a powerful tool for modeling nuclear radiation interaction with matter. A variety of MC software packages has been developed, especially for applications in radiation therapy. Most widely used MC packages require users to write their own input scripts for their systems, which can be a time consuming and error prone process and requires extensive user experience.

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Objective: Transarterial Radioembolization (TARE) with Y-loaded glass microspheres is a locoregional treatment option for Hepatocellular Carcinoma (HCC). Post-treatment Y bremsstrahlung imaging using Single-Photon Emission Tomography (SPECT) is currently a gold-standard imaging modality for quantifying the delivered dose. However, the nature of bremsstrahlung photons causes difficulty for dose estimation using SPECT imaging.

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The Monte Carlo method is employed in this study to simulate the proton irradiation of a water-gel phantom. Positron-emitting radionuclides such as 11C, 15O, and 13N are scored using the Particle and Heavy Ion Transport Code System Monte Carlo code package. Previously, it was reported that as a result of 16O(p,2p2n)13N nuclear reaction, whose threshold energy is relatively low (5.

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