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Radiocesium-bearing microparticles cause a large variation in $$^{137}$$Cs activity concentration in the aquatic insect ${it Stenopsyche marmorata}$ (Tricoptera: Stenopsychidae) in the Ota River, Fukushima, Japan

石井 弓美子*; 三浦 輝*; Jo, J.*; 辻 英樹*; 斎藤 梨絵; 小荒井 一真; 萩原 大樹; 漆舘 理之*; 錦織 達啓*; 和田 敏裕*; et al.

PLOS ONE (Internet), 17(5), p.e0268629_1 - e0268629_17, 2022/05

本研究では、福島県太田川で採集した解虫性トビケラ(Stenopsyche marmorata)および肉食性ヘビトンボ(Protohermes grandis)幼虫の水生昆虫個体における$$^{137}$$Cs放射能濃度のばらつきを調査した。トビケラ幼虫は散発的に高い放射能を示したが、ヘビトンボ幼虫ではばらつきは見られなかった。オートラジオグラフィーと走査型電子顕微鏡による分析から、これらのトビケラ幼虫試料には、不溶性のCs含有ケイ酸塩ガラス粒子である放射性Cs含有微粒子(CsMPs)が含まれていることが確認された。また、CsMPsはトビケラ幼虫の餌となりうるペリフィトンや漂流粒子状有機物にも含まれており、幼虫はCsMPsを同サイズの餌粒子とともに摂取している可能性が示唆された。淡水生態系におけるCsMPsの分布や生物による取り込みは比較的知られていないが、本研究はCsMPsが水生昆虫に取り込まれることを実証している。


Deexcitation dynamics of muonic atoms revealed by high-precision spectroscopy of electronic $$K$$ X rays

奥村 拓馬*; 東 俊行*; Bennet, D. A.*; Caradonna, P.*; Chiu, I. H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; 橋本 直; et al.

Physical Review Letters, 127(5), p.053001_1 - 053001_7, 2021/07

 被引用回数:3 パーセンタイル:45.66(Physics, Multidisciplinary)



Three-dimensional and multienergy $$gamma$$-ray simultaneous imaging by using a Si/CdTe Compton camera

鈴木 義行*; 山口 充孝; 小高 裕和*; 島田 博文*; 吉田 由香里*; 鳥飼 幸太*; 佐藤 隆博; 荒川 和夫*; 河地 有木; 渡辺 茂樹; et al.

Radiology, 267(3), p.941 - 947, 2013/06

 被引用回数:19 パーセンタイル:61.05(Radiology, Nuclear Medicine & Medical Imaging)

Capabillity tests of 3D imaging for medical applications were performed by using a new Compton camera. $$^{18}$$F, $$^{131}$$I and $$^{67}$$Ga separately compacted into micro tubes were injected subcutaneously into a Wister rat and imaged after sacrifice of the rat (ex-vivo model). In a separate experiment $$^{111}$$In-chloride and $$^{131}$$I-Methylnorcholestenol were injected into a rat intravenously and $$^{64}$$Cu was injected into the stomach orally just before imaging (more physiological model). The Compton camera demonstrated its 3D multinuclear imaging capability by separating out the three nuclear distributions clearly in ex-vivo model. In the more physiological model, the distributions of $$^{131}$$I and $$^{64}$$Cu were clearly imaged although $$^{111}$$In was difficult to visualize due to blurring at low energy region of $$gamma$$-ray. In conclusion, our new Compton camera successfully demonstrated highly resolved multiplanar and multinuclear $$gamma$$-ray simultaneous imaging.


An Evaluation of three-dimensional imaging by use of Si/CdTe Compton cameras

山口 充孝; 長尾 悠人; 河地 有木; 藤巻 秀; 神谷 富裕; 小高 裕和*; 国分 紀秀*; 武田 伸一郎*; 渡辺 伸*; 高橋 忠幸*; et al.

Proceedings of 2013 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC), 3 Pages, 2013/00

A Monte Carlo simulation system was developed to estimate the response of Compton camera against $$gamma$$-ray emissions from RI spots in a PET-standard human-body phantom. The quality of the three-dimensional imaging program for the Si/CdTe Compton camera to reconstruct the image of the RI spots in a phantom was evaluated by the system, when the phantom has three hot sphere-regions with the same known RI density and different diameters, in other words, different known intensities. The density values of the hot regions reconstructed by the three-dimensional imaging program for the Compton camera were consistent to the known intensities of the RI. It demonstrates sufficient quality of the program for Si/CdTe Compton camera to image RI spots in the phantom.


A New method for monitoring beam range by measuring low energy photons

山口 充孝; 鳥飼 幸太*; 河地 有木; 島田 博文*; 佐藤 隆博; 長尾 悠人; 藤巻 秀; 国分 紀秀*; 渡辺 伸*; 高橋 忠幸*; et al.

Proceedings of 2013 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC), 2 Pages, 2013/00

We studied a new method to monitor a beam range in heavy-ion radiation therapy on the basis of measurement of low energy photons emitted from a track of the ion beam. A 290 MeV/u carbon beam was injected into a cylindrical water phantom. A CdTe semiconductor detector with a lead slit having a width of 2 mm was placed at a side of the phantom. In order to measure the position dependence of the low energy photon count, the beam range was varied by changing the energy of injected ions using a binary energy degrader placed about 100 cm upstream of the beam focal point. The measured photon count decreased when the detector got closer to the end point of the beam range and the derivative of the photon count values sharply changed within a depth variation of a few mm in front of the range position. This was explained by our theoretical study assuming secondary electron bremsstrahlung. These results indicate that this new method could be useful to estimate the range position from the observation of bremsstrahlung with an accuracy of a few mm.


High-resolution Compton cameras based on Si/CdTe double-sided strip detectors

小高 裕和*; 一戸 悠人*; 武田 伸一郎*; 福山 太郎*; 萩野 浩一*; 齋藤 新也*; 佐藤 有*; 佐藤 悟朗*; 渡辺 伸*; 国分 紀秀*; et al.

Nuclear Instruments and Methods in Physics Research A, 695, p.179 - 183, 2012/12

 被引用回数:22 パーセンタイル:84.81(Instruments & Instrumentation)



Applications and imaging techniques of a Si/CdTe Compton $$gamma$$-ray camera

武田 伸一郎*; 一戸 悠人*; 萩野 浩一*; 小高 裕和*; 湯浅 孝行*; 石川 真之介*; 福山 太郎*; 齋藤 新也*; 佐藤 有*; 佐藤 悟朗*; et al.

Physics Procedia, 37, p.859 - 866, 2012/10

 被引用回数:21 パーセンタイル:98.52

ASTRO-Hミッションのために開発されたSi/CdTe半導体両面ストリップ検出器(DSD)を利用したコンプトンカメラを用い、放射線ホットスポットのモニタリングの実行可能性チェックを目的とした複数放射線源の画像化実験を行った。本装置は半導体検出器によって与えられた良好なエネルギー分解能により、既に商業的な画像処理システムが提供するホットスポットの画像可能力に加え、複数の放射性同位元素を同定する能力を有する。今回の実験では、$$^{133}$$Ba(356keV), $$^{22}$$Na(511keV)及び$$^{137}$$Cs(662keV)の三放射性同位元素を同時に測定し、これらの画像化に成功した。5つの検出器モジュール(有効面積: 1.7$$times$$10$$^{-3}$$cm$$^2$$)を積み重ねることによって、662keVの$$gamma$$線に対し、検出効率1.68$$times$$10$$^{-4}$$、及び、3.8度の角度分解能を確認した。本装置は、より多くの検出器モジュールをスタックすることにより、さらに大きな検出効率を達成することが可能である。


Beam range estimation by measuring bremsstrahlung

山口 充孝; 鳥飼 幸太*; 河地 有木; 島田 博文*; 佐藤 隆博; 長尾 悠人; 藤巻 秀; 国分 紀秀*; 渡辺 伸*; 高橋 忠幸*; et al.

Physics in Medicine & Biology, 57(10), p.2843 - 2856, 2012/05

 被引用回数:30 パーセンタイル:73.02(Engineering, Biomedical)

We describe a new method for estimating the beam range in heavy-ion radiation therapy by measuring the ion beam bremsstrahlung. We experimentally confirm that the secondary electron bremsstrahlung process provides the dominant bremsstrahlung contribution. A Monte Carlo simulation shows that the number of background photons from annihilation $$gamma$$ rays is about 1% of the bremsstrahlung strength in the low-energy region used in our estimation (63-68 keV). Agreement between the experimental results and the theoretical prediction for the characteristic shape of the bremsstrahlung spectrum validates the effectiveness of our new method in estimating the ion beam range.


Three-dimensional imaging test for a head module of a Si/CdTe Compton camera for medical application

山口 充孝; 河地 有木; 神谷 富裕; 佐藤 隆博; 鈴井 伸郎; 藤巻 秀; 小高 裕和*; 石川 真之介*; 国分 紀秀*; 渡辺 伸*; et al.

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 145, 2012/01



Development of head module for multi-head Si/CdTe Compton camera for medical applications

山口 充孝; 河地 有木; 鈴井 伸郎; 藤巻 秀; 神谷 富裕; 小高 裕和*; 石川 真之介*; 国分 紀秀*; 渡辺 伸*; 高橋 忠幸*; et al.

Nuclear Instruments and Methods in Physics Research A, 648(Suppl.1), p.S2 - S7, 2011/08

 被引用回数:1 パーセンタイル:12.17(Instruments & Instrumentation)



Counting rate performance measurement of newly developed Si/CdTe Compton camera for biological and medical applications

山口 充孝; 河地 有木; 神谷 富裕; 鈴井 伸郎; 藤巻 秀; 小高 裕和*; 石川 真之介*; 国分 紀秀*; 渡辺 伸*; 高橋 忠幸*; et al.

2010 IEEE Nuclear Science Symposium Conference Record (CD-ROM), p.2004 - 2007, 2010/10

In recent developed radionuclide-based imaging technologies utilized for biological and medical studies, wide dynamic range of radiation intensity with a good quantitative linearity is one of the most important factors. However, the linearity of a detector or a sensor generally breaks due to the dead-time increasing in high counting rate. Therefore, in case of an imaging camera, which is a large set of detectors, it is essential to measure the sensitivity profile of it varying with the radiation source intensity for correction of nonlinearity of each detector. Si/CdTe Compton camera is comprised of two layered double-sided Si strip detectors and two layered double-sided CdTe strip detectors with a four-layer laminated structure. For imaging, the source positions of $$gamma$$-rays are identified by analysing the deposited energies and the scattering angles from counted events in those of detectors. In this work, the Compton camera that was newly developed for biological and medical applications was investigated on the counting rate performance, and the sensitivity profile of this highly complicated imaging system was measured using a $$^{18}$$F point $$gamma$$-ray source. The intense source of 20 MBq was used to measure the sensitivity profiles for a wide range of counting rate in a short period. The result was compared with a calculation using a model considering the dead time of the detection system.


Experimental results of the $$gamma$$-ray imaging capability with a Si/CdTe semiconductor Compton camera

武田 伸一郎*; 青野 博之*; 奥山 翔*; 石川 真之介*; 小高 裕和*; 渡辺 伸*; 国分 紀秀*; 高橋 忠幸*; 中澤 知洋*; 田島 宏康*; et al.

IEEE Transactions on Nuclear Science, 56(3), p.783 - 790, 2009/06

 被引用回数:52 パーセンタイル:96(Engineering, Electrical & Electronic)

A semiconductor Compton camera that combines silicon (Si) and Cadmium Telluride (CdTe) detectors was developed, and its imaging capability was examined with various kinds of $$gamma$$-ray targets such as a point source, arranged point sources and an extended source. The camera consists of one double-sided Si strip detector and four layers of CdTe pad detectors, and was designed to minimize the distance between a scatterer and the target. This is because the spatial resolution with Compton imaging improves as the target approaches the scatterer. This new camera realizes a minimum distance of 25 mm. By placing the target at a distance of 30 mm from the detector, resolving power better than 3 mm was demonstrated experimentally for a 364 keV ($$^{131}$$I) $$gamma$$-ray. Positional determination with accuracy of 1 mm was also demonstrated. As a deconvolution method, we selected the iteration algorithm (called List-Mode Expectation-Maximizing Maximum Likelihood), and applied it to several kinds of experimental data. The Compton back projection images of the arranged point sources and an extended object were successfully deconvolved.


Basic characteristics of a newly developed Si/CdTe Compton camera for medical imaging

河地 有木; 渡邉 茂樹; 佐藤 隆博; 荒川 和夫; 武田 伸一郎*; 石川 真之介*; 青野 博之*; 渡辺 伸*; 山口 充孝*; 高橋 忠幸*; et al.

2008 IEEE Nuclear Science Symposium Conference Record (CD-ROM), p.1540 - 1543, 2008/10

The Compton camera is a very promising medical imaging system when we consider multiple radionuclide imaging and its sensitivity, portability and compactness. We have developed a Compton camera by using Si and CdTe semiconductors for medical imaging. The prototype Compton camera head consists of a double-sided Si strip detector (DSSD) module as the scatter detector and four layered 16 CdTe pixel detector modules as the absorber detector. The DSSD has an area of 2.56$$times$$2.56 cm, a thickness of 500 $$mu$$m and a strip pitch of 400 $$mu$$m. The CdTe pixel detector has an area of 1.35$$times$$1.35 cm, a thickness of 500 $$mu$$m and a pixel size of 1.35 mm$$^{2}$$. The high-energy resolution detectors (DSSD: $$Delta$$E/E$$sim$$2.5%, CdTe: $$Delta$$E/E$$sim$$1%) enable detect the Compton scatter events of the incident $$gamma$$-rays, in consequence image radioactive multi-nuclide tracer. We evaluated distributions of sensitivity and spatial resolution, and rat study was performed with three tracers ($$^{111}$$In, $$^{131}$$I, $$^{64}$$Cu) concurrently-administered. As results, lines of point-source data indicated 4 mm spatial resolution in the center of field of view (FOV) in this experimental design, and a characteristic manner of the distributions in the Compton camera FOV was shown. The nuclides in the rat body were distinguished by the $$gamma$$-ray energies, each tracer imaged separately in vivo, and the difference in distribution among the nuclide was visualized successfully.


Monte Carlo simulation of multi-head Si/CdTe Compton camera for medical imaging

山口 充孝*; 河地 有木; 渡辺 伸*; 小高 裕和*; 武田 伸一郎*; 石川 真之介*; 青野 博之*; 高橋 忠幸*; 荒川 和夫; 中野 隆史*

2008 IEEE Nuclear Science Symposium Conference Record (CD-ROM), p.4000 - 4002, 2008/10

We have developed a prototype of Compton camera using Si/CdTe semiconductors for medical imaging. In the case where the detection area of Compton camera is restricted to small region, position resolution of depth direction is expected to be low. To overcome this weakness, we propose multi-head Compton camera. In this work, we evaluated the position resolutions of single- and double-head Compton camera by using Monte Carlo simulation. After the Monte Carlo simulation, two hit Compton event was selected, and back-projection and image reconstruction were performed in 3D-space. Consequently, the position resolution of the z-axis was about 5.6 mm for double-head camera whereas about 27 mm for single-head camera. These results indicate that the position resolution is improved and clear 3D-image is taken by using multi-head Compton camera.



笹島 唯之; 正木 圭; 櫻井 真治; 芝間 祐介; 林 孝夫; 鈴木 優; 高橋 龍吉

平成18年度名古屋大学総合技術研究会装置技術研究会報告集, p.148 - 151, 2007/03




浅野 隆; 藤原 茂雄; 高橋 三郎; 根本 忠行*; 佐藤 隆*; 国安 和房*; 蛭田 一彦*

核物質管理学会(INMM)日本支部第28回年次大会論文集(CD-ROM), 11 Pages, 2007/00



Fabrication of 8Cr-2W ferritic steel tile for reduction in toroidal magnetic field ripple on JT-60U

工藤 祐介; 沢井 友次; 櫻井 真治; 正木 圭; 鈴木 優; 笹島 唯之; 林 孝夫; 高橋 龍吉*; 本田 正男; 實川 資朗; et al.

Journal of the Korean Physical Society, 49(96), p.S297 - S301, 2006/12



Reduction of toroidal magnetic field ripple with ferritic steel armors in JT-60U

櫻井 真治; 正木 圭; 芝間 祐介; 篠原 孝司; 鈴木 優; 笹島 唯之; 森岡 篤彦; 林 孝夫; 高橋 龍吉; 沢井 友次; et al.

no journal, , 



植物分子イメージングの試み,2; 複数種元素動態の同時イメージングを可能にする

河地 有木; 藤巻 秀; 鈴井 伸郎; 石井 里美; 松橋 信平; 佐藤 隆博; 渡辺 伸*; 武田 伸一郎*; 高橋 忠幸*

no journal, , 



Multi-tracer imaging using CdTe $$gamma$$-camera for studying molecular imaging for plant science

河地 有木; 藤巻 秀; 鈴井 伸郎; 石井 里美; 石岡 典子; 松橋 信平; 佐藤 隆博; 渡辺 伸*; 武田 伸一郎*; 高橋 忠幸*; et al.

no journal, , 

We have developed two imaging systems for plant science research, which images physiological processes in living systems noninvasively and quantitatively. One is the positron emitting tracer imaging system, which image the tracers of nutrients and pollutants in intact plants. In addition, for the numerical analysis of plant physiological functions, tracer kinetics have analyzed with simplified physiological model of test plants. The another is a prototype multi-element imaging system for plant study using CdTe semiconductor detector, which has high-energy resolution. The feasibility of this system for $$gamma$$-ray emission imaging of radioactive multi-nuclide tracer was examined by imaging experiment with a plant. The distribution of the two tracers, technetium and thallium, fed to a tobacco plant was successfully visualized for each nuclide simultaneously. The presented imaging methods will yield plant molecular imaging, which visualizes dynamics of some competitive elements in intact plant, non-invasively and quantitatively.

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