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論文

Remote detection of radioactive hotspot using a Compton camera mounted on a moving multi-copter drone above a contaminated area in Fukushima

佐藤 優樹; 小澤 慎吾*; 寺阪 祐太; 峯本 浩二郎*; 田村 智志*; 新宮 一駿*; 根本 誠*; 鳥居 建男

Journal of Nuclear Science and Technology, 57(6), p.734 - 744, 2020/06

 被引用回数:1 パーセンタイル:21.8(Nuclear Science & Technology)

The Fukushima Daiichi Nuclear Power Station, operated by Tokyo Electric Power Company Holdings, Inc., suffered a meltdown as a result of a large tsunami triggered by the Great East Japan Earthquake on March 11, 2011. To proceed with the environmental recovery by decontamination, drawing a radiation distribution map that can indicate the distribution of radioactive substances is extremely important to establish detailed decontamination plans. We developed a remote radiation imaging system consisting of a lightweight Compton camera and a multi-copter drone to remotely measure the distribution of the radioactive substances. This system can perform radiation imaging using a Compton camera while flying and moving. In addition, it is also possible to draw the distribution of radioactive substances three-dimensionally by projecting the radiation image measured with the Compton camera on a three-dimensional topography model separately acquired by a 3D-LiDAR. We conducted a survey of radioactive hotspots in difficult-to-return zone in the coastal area of Fukushima, Japan. The drone system succeeded in three-dimensional visualization of several hotspots deposited on the ground. Such remote technology would be useful not only for monitoring the difficult-to-return zone, but also for monitoring distribution of radioactive substances inside the site of the FDNPS where decommissioning work is ongoing.

論文

Visualization of radioactive substances using freely moving gamma-ray imager based on Structure from Motion

佐藤 優樹; 鳥居 建男

Proceedings of International Youth Nuclear Congress 2020 (IYNC 2020) (Internet), 4 Pages, 2020/05

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., suffered a meltdown as a result of a large tsunami triggered by the Great East Japan Earthquake on March 11, 2011. We have been conducting demonstration tests for detection of radioactive hotspots inside the FDNPS buildings using a Compton camera, a kind of gamma-ray imager. In this work, we introduced the 3D visualization of radioactive substances by using combination of the Compton camera and optical camera based on Structure from Motion (SfM). By taking photographs of the experimental environment while freely moving, a 3D structural model of the environment can be reconstructed from the multiple photographs, and the movement trajectory of the optical camera can be estimated simultaneously using the SfM. Furthermore, the radioactive substances can be visualized by drawing an image of the radioactive substances on the 3D structural model using gamma-ray data acquired by the Compton camera. In the demonstration, we succeeded in visualizing a $$^{137}$$Cs-radiation source on the 3D structural model of the experimental environment while freely moving these devices. This technology is useful for making it easy to recognize radioactive substances in decommissioning work site such as the FDNPS.

論文

Radiation imaging using a compact Compton camera mounted on a crawler robot inside reactor buildings of Fukushima Daiichi Nuclear Power Station

佐藤 優樹; 寺阪 祐太; 宇津木 弥*; 菊地 弘幸*; 清岡 英男*; 鳥居 建男

Journal of Nuclear Science and Technology, 56(9-10), p.801 - 808, 2019/09

 被引用回数:4 パーセンタイル:18.47(Nuclear Science & Technology)

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown in the aftermath of a large tsunami caused by the Great East Japan Earthquake of 11 March 2011. Measurement of radiation distribution inside the FDNPS buildings is indispensable to execute decommissioning tasks in the reactor buildings. We conducted a radiation imaging experiment inside the reactor building of Unit 1 of FDNPS by using a compact Compton camera mounted on a crawler robot and remotely visualized gamma-rays streaming from deep inside the reactor building. Moreover, we drew a radiation image obtained using the Compton camera onto the three-dimensional (3-D) structural model of the experimental environment created using photogrammetry. In addition, the 3-D model of the real working environment, including the radiation image, was imported into the virtual space of the virtual reality system. These visualization techniques help workers recognize radioactive contamination easily and decrease their own exposure to radiation because the contamination cannot be observed with the naked eye.

論文

福島第一事故由来物質に対する環境モニタリング手法の最先端,3; 事故7年後の福島の放射線分布状況および環境モニタリング技術の最前線

眞田 幸尚

日本原子力学会誌, 61(6), p.453 - 456, 2019/06

福島県で実施されている大規模な放射線モニタリングの情報を整理するとともに、福島第一原子力発電所事故直後からの線量率の変化傾向の考察および住民のニーズに応えるための放射線計測技術の新技術について紹介する。

論文

Image reconstruction of radioactive contamination due to the Fukushima-Daiichi Nuclear Power Station Accident using a compact Compton camera

佐藤 優樹; 寺阪 祐太; 宮村 浩子; 冠城 雅晃; 谷藤 祐太; 川端 邦明; 鳥居 建男

Reactor Dosimetry; 16th International Symposium on Reactor Dosimetry (ISRD-16) (ASTM STP 1608), p.428 - 436, 2018/11

 被引用回数:0 パーセンタイル:100

We developed a lightweight compact Compton camera to measure the distribution of radioactive contamination inside the Fukushima Daiichi Nuclear Power Station. We conducted performance evaluation tests in the coastal area of Fukushima, Japan, using the camera, which employs a cerium (Ce)-doped GAGG (Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$) scintillator coupled with a multipixel photon counter. The camera can clearly visualize spreading of radioactivity along the ground surface. In addition, we performed three-dimensional image reconstruction of the distribution of radioactive contamination using the multi-angle data obtained with the Compton camera. We succeeded in obtaining a three-dimensional image of radioactive contamination in the outdoor area.

論文

Radiation imaging using a compact Compton camera inside the Fukushima Daiichi Nuclear Power Station building

佐藤 優樹; 谷藤 祐太; 寺阪 祐太; 宇佐美 博士; 冠城 雅晃; 川端 邦明; 宇津木 弥*; 菊地 弘幸*; 高平 史郎*; 鳥居 建男

Journal of Nuclear Science and Technology, 55(9), p.965 - 970, 2018/09

 被引用回数:8 パーセンタイル:11(Nuclear Science & Technology)

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown after the occurrence of a large tsunami caused by the Great East Japan Earthquake of March 11, 2011. The radiation distribution measurements inside the FDNPS buildings are indispensable to execute decommissioning tasks in the reactor buildings. We conducted the radiation imaging experiment inside the turbine building of Unit 3 of the FDNPS using a compact Compton camera, and succeeded in visualizing the high-dose contamination (up to 3.5 mSv/h). We also drew a three-dimensional radiation distribution map inside the turbine building by integrating the radiation image resulting from the Compton camera into the point cloud data of the experimental environment acquired using the scanning laser range finder. The radiation distribution map shows the position of these contaminations on the real space image of the turbine building. The radiation distribution map helps workers to easily recognize the radioactive contamination and to decrease the radiation exposure; the contamination cannot be observed with the naked eye, naturally.

論文

A 3D radiation image display on a simple virtual reality system created using a game development platform

佐藤 優樹; 寺阪 祐太; 小澤 慎吾*; 谷藤 祐太; 鳥居 建男

Journal of Instrumentation (Internet), 13(8), p.T08011_1 - T08011_10, 2018/08

 被引用回数:3 パーセンタイル:60.15(Instruments & Instrumentation)

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., suffered a meltdown after a large tsunami caused by the Great East Japan Earthquake on March 11, 2011. The measurement of radiation distribution inside FDNPS buildings is indispensable for executing appropriate decommissioning tasks in the reactor's buildings. In addition, it is extremely important to accurately predict the location of radioactive contamination beforehand because the working time is limited owing to radiation exposure to workers. In this paper, a simple virtual reality (VR) system that can detect radioactive substances in virtual space has been developed to simulate real working environments. A three-dimensional (3D) photo-based model of the real working environment, including an image of the radioactive substance, was imported into the virtual space of the VR system. The developed VR system can be accessed using a smartphone and a cardboard goggle. The VR system is expected to be useful for preliminary training of workers and for recognizing radioactive hotspots during decommissioning of the work environment.

論文

A Three-dimensional radiation image display on a real space image created via photogrammetry

佐藤 優樹; 小澤 慎吾*; 谷藤 祐太; 鳥居 建男

Journal of Instrumentation (Internet), 13(3), p.P03001_1 - P03001_8, 2018/03

 被引用回数:4 パーセンタイル:50.42(Instruments & Instrumentation)

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown after the large tsunami caused by the Great East Japan Earthquake of March 11, 2011. Radiation distribution measurements inside FDNPS buildings are indispensable to execute decommissioning tasks in the reactor buildings. We have developed a method of three-dimensional (3-D) image reconstruction for radioactive substances using a compact Compton camera. We also succeeded in visually recognize the position of the radioactive substances on the real space by integration of the 3D radiation image and the 3D photo-model created by photogrammetry.

論文

Remote radiation imaging system using a compact $$gamma$$-ray imager mounted on a multicopter drone

佐藤 優樹; 小澤 慎吾*; 寺阪 祐太; 冠城 雅晃; 谷藤 祐太; 川端 邦明; 宮村 浩子; 和泉 良*; 鈴木 敏和*; 鳥居 建男

Journal of Nuclear Science and Technology, 55(1), p.90 - 96, 2018/01

 被引用回数:12 パーセンタイル:4.18(Nuclear Science & Technology)

A remote radiation imaging system comprising a lightweight Compton camera and a multicopter drone was developed to remotely and quickly measure radioactive contamination inside the buildings of the Fukushima Daiichi Nuclear Power Station (FDNPS). The drone system is used for measuring detailed radiation distributions in narrow areas, which have been difficult to gauge with conventional aircraft monitoring using helicopters. A measurement of radiation distributions in outdoor environments in the coastal areas of Fukushima, Japan, was performed. The drone system with the Compton camera succeeded in remote observations of dense hotspots from the sky over a contaminated area near the FDNPS. The time required for image reconstruction is approximately 550 s in the case of a 9-m flight altitude for the hotspots with a surface dose rate of several tens of $$mu$$Sv/h. This drone system will be used inside the buildings of the FDNPS for remote measurement of radioactive contamination.

論文

Development of compact Compton camera for 3D image reconstruction of radioactive contamination

佐藤 優樹; 寺阪 祐太; 小澤 慎吾*; 宮村 浩子; 冠城 雅晃; 谷藤 祐太; 川端 邦明; 鳥居 建男

Journal of Instrumentation (Internet), 12(11), p.C11007_1 - C11007_8, 2017/11

 被引用回数:7 パーセンタイル:42.03(Instruments & Instrumentation)

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown after the large tsunami caused by the Great East Japan Earthquake of March 11, 2011. Very large amounts of radionuclides were released from the damaged plant. Radiation distribution measurements inside the building of FDNPS are indispensable to execute the decommission tasks in the reactor buildings. We have developed a light-weight compact Compton camera to three-dimensionally measure the distribution of radioactive contamination inside FDNPS. The total weight of the Compton camera is lower than 1.0 kg. The $$gamma$$-ray sensor of the Compton camera employs the Ce-doped GAGG scintillators coupled with a multi-pixel photon counter (MPPC: Hamamatsu Photonics K.K.,). We performed the 3D image reconstruction of the $$^{137}$$Cs-radioactive sources as shown in Fig. 1; the 3D radiation image is reconstructed using the multi-angle data measured with the Compton camera. Here, we introduce the development status of the 3D radiation imaging system consisting of the Compton camera. Moreover, we present the results of a performance evaluation test for 3D image reconstruction of radioactive contaminations in details.

論文

Application of invasion mathematical model in dosimetry for boron neutron capture therapy for malignant glioma

山本 和喜; 熊田 博明; 中井 啓*; 遠藤 聖*; 山本 哲哉*; 松村 明*

Proceedings of 11th World Congress on Neutron Capture Therapy (ISNCT-11) (CD-ROM), 14 Pages, 2004/10

放射線治療上、細胞密度分布を考慮した線量分布が要求されている。次世代ホウ素中性子捕捉療法(BNCT)用線量評価システムの開発に向けて、照射領域を決定するための新しい方法を提案する。医療画像を用いては腫瘍細胞の拡散浸潤度を十分に評価することはできない。そのためBNCTの治療プロトコールを参考に、腫瘍を囲む照射領域はガドリニウムを用いた核磁気共鳴画像(MRI)のT1画像上に強調される領域から通常2cm余裕を見た任意の距離に拡張する領域として設定されている。この研究では、照射領域境界の細胞濃度を時間-空間球座標系の腫瘍細胞拡散モデルによって議論し、BNCT照射後に生存する腫瘍細胞密度分布を仮想脳ファントムのための2領域拡散モデルによって予測した。

論文

Construction and commissioning of a 215-m-long beamline at SPring-8

後藤 俊治*; 竹下 邦和*; 鈴木 芳生*; 大橋 治彦*; 浅野 芳裕; 木村 洋昭*; 松下 智裕*; 八木 直人*; 一色 康之*; 山崎 裕史*; et al.

Nuclear Instruments and Methods in Physics Research A, 467-468(Part1), p.682 - 685, 2001/07

イメージング技術開発や、X線光学素子開発,物性研究のためのトモグラフィーや医学イメージング,トポグラフィー研究等を目的とした、最初の中央ビームラインをSPring-8で構築した。この結果、大視野でコヒーレントな光ビームを得ることに成功した。またこのビームラインを用いて、300mmのシリコンクリスタルのone-shotトポグラフのような、予備実験を成功裡に終わることができた。これらについて論じた。

論文

A Factorization of LET effects of ion induced photostimulated luminescence

阿部 健*; 斎藤 究*; 藤 健太郎; 小嶋 拓治; 酒井 卓郎

JAERI-Review 99-025, TIARA Annual Report 1998, p.103 - 105, 1999/10

イメージングプレート(IP, 組成BaFBr:Eu$$^{2+}$$)を用いてサイクロトロンから得られるイオンビームの線種、エネルギー弁別測定技術を開発するため、輝尽発光のLET特性の機構に関する研究を行った。この結果、IPの励起スペクトル応答における線種・エネルギー依存性が、入射イオンの蛍光体層への侵入深さによるものだけでなく、特に重イオンでは入射イオンのLET効果にもよることが、スペクトル成分の分離解析によりわかった。また、このLET効果は、IP中のBr及びFのF$$^{-}$$センターのレベルに相当するスペクトルに現れていることが明らかになった。さらに、1kGy以上の線量域における輝尽発光量の低下は、基材のポリエチレンテレフタレートの劣化でなく、輝尽発光体の損傷によることがわかった。これらにより、IP応答のLET特性及びその機構をほぼ明らかにした。

論文

A Response of an imaging plate to heavy ion beams and its LET effects

阿部 健*; 小嶋 拓治; 鈴谷 卓之*; 村上 泰朗*; 斉藤 究*; 藤 健太郎*; 酒井 卓郎; 武部 雅汎*

Radiation Detectors and Their Uses, p.323 - 328, 1998/00

異種放射線混在場における線種・エネルギー弁別画像計測技術を確立するため、イメージングプレート(IP,輝尽発光体:BaFBr:Eu$$^{2+}$$)の放射線応答特性を調べており、既にX($$gamma$$)線、電子線及び軽イオンビームに関しては、IPに含まれる色素の効果や放射線の飛程のちがいを利用した弁別方法を見出した。今回はより高い線エネルギー付与(LET)をもつKrまでの重イオンに対する応答特性を調べた。照射後のIPの光励起スペクトルは、500及び600nmにおいてそれぞれF及びBrの色センターに起因するピークをもつが、これを近似関数を用いて成分分離すると他にも小ピークがあり、これらの存在と強度変化が元のピークの位置や形を決めていることが新たにわかった。さらにこの成分がフェーディング挙動に関連することが示唆された。また照射後光ブリーチングを行うと、ピーク成分が個別に励起光強度に依存し、この現象が機構解明に結びつくことが考えられた。

口頭

Live cell imaging study on biological effects induced by X-ray microbeam irradiation

神長 輝一; 嘉成 由紀子*; 坂本 由佳*; 野口 実穂; 成田 あゆみ*; 藤井 健太郎; 宇佐美 徳子*; 小林 克己*; 鈴木 啓司*; 横谷 明徳

no journal, , 

We performed selective exposure to HeLa-Fucci cells of a specific cell cycle using synchrotron X-ray microbeam. The results suggested that, not only the irradiated, but also non-irradiated cells surrounding the exposed cells also undergo cell cycle arrest as a consequence of a novel "bystander" effect. When irradiated to spheroids of the HeLa-Fucci cells as a model of 3D cellular tissues, we have succeeded to track the cell cycle modulations in the spheroid using a confocal microscopy. Further we performed sub-cellular irradiation to target a cell nucleus or cytoplasm to look at the effect on mitochondria in human fibroblast cells stained with a specific chemical. Even when the nucleus was irradiated, the potential of mitochondria was enhanced for 12 h. It is inferred that not only DNA damage repair but also certain responses to cellular damage might need excess production of ATP. These clearly show that the live cell imaging appears to be a promising method for single cell tracking.

口頭

イメージングXAFSによる異種元素間の化学的相関解析

岡本 芳浩; 永井 崇之; 小林 博美*; 畠山 清司*; 塩飽 秀啓

no journal, , 

イメージングXAFS分析の拡張版である、異種元素間の化学的な相関解析の技術開発を進め、様々な物質への適用を図った。これは、通常のイメージングXAFS測定を、複数の元素に同時に適用することで、それらの元素の分布の特徴にあわせて、XAFSスペクトルを空間選択的に抽出する新しい分析法である。これまでに、土壌中の鉄とセシウム、吸着材中のチタンとストロンチウム、ガラス固化試料中のルテニウムとロジウムなどにおいて、相関関係の導出に成功している。本研究では、この手法をより実用レベルに拡張すべく、様々な条件下で調製された模擬廃液成分を含むホウケイ酸ガラス試料を対象に試験を行い、ガラス中の白金族元素間の相関関係の導出を試みた。

口頭

Compact Compton camera for radiation distribution imaging under high dose rate environments

佐藤 優樹; 寺阪 祐太; 冠城 雅晃; 谷藤 祐太; 宇佐美 博士; 宮村 浩子; 小澤 慎吾*; 和泉 良*; 川端 邦明; 鈴木 敏和*; et al.

no journal, , 

The development of quick radiation imaging methods in the high dose rate environments is very important to accelerate decommissioning of the Fukushima Daiichi Nuclear Power Station (FDNPS). We have developed a compact Compton camera for measurement of radioactive contamination inside FDNPS. We conducted a performance evaluation test inside the $$gamma$$-ray irradiation facility, and the Compton camera can visualize the $$^{137}$$Cs-irradiation source under the dose rate of 1 mGy/h. We also developed the remote radiation imaging system consisting of the Compton camera and a multicopter-type drone. The drone system succeeded in observing the $$^{137}$$Cs-radioactive source, which was set on the floor surface, remotely. We plan to use the Compton camera and the drone system inside the buildings of FDNPS.

口頭

Radiation image display on a simple virtual reality system

佐藤 優樹; 小澤 慎吾*; 谷藤 祐太; 鳥居 建男

no journal, , 

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown after the large tsunami caused by the Great East Japan Earthquake of March 11, 2011. Radiation distribution measurements inside the buildings of the FDNPS are indispensable to execute the decommission tasks because the information would be important to predict risk to workers and to decrease the amount of radiation exposure. In this work, we developed a simple virtual reality (VR) system that can perceive the radioactive substances in the virtual space reproducing working environments. The VR was developed with Unity 5.6 which is a game development engine. The developed VR will be experienced using a smartphone and a cardboard goggle. The advantage of using smartphones is that it has a gyro sensor, which users can use to look over the VR space. In addition, it is owned by many users. The VR system is expected to be useful for preliminary training of workers and recognition of radioactive hot spots in the decommissioning work environment.

口頭

Visualization of radioactive substances by integrating radiation measurement, remote technology, and 3-D optical measurement

佐藤 優樹; 寺阪 祐太; 冠城 雅晃; 谷藤 祐太; 鳥居 建男

no journal, , 

We visualized a hotspot from the sky over the waste storage space inside the Fukushima Daiichi Nuclear Power Station using a remote radiation imaging system consisting of a drone equipped with a Compton camera. By superimposing the images of the hotspots on the 3D building model of the waste storage space created using a photogrammetry, we succeeded in drawing the map that can easily recognize the positions of the hotspots in the actual working environment.

口頭

Visualization of radioactive substances on a 3D building model of the Fukushima Daiichi Nuclear Power Station

佐藤 優樹; 寺阪 祐太; 宇津木 弥*; 菊地 弘幸*; 高平 史郎*; 鳥居 建男

no journal, , 

The Fukushima-Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown after the occurrence of a large tsunami caused by the Great East Japan Earthquake on March 11, 2011. The radiation distribution measurements inside the site of the FDNPS are indispensable to execute decommissioning tasks. We have developed a three-dimensional (3D) radiation imaging technique for grasping the location of the high-dose rate region (hotspot) using a compact Compton camera and a photogrammetry technique to create 3D optical images. We succeeded in detecting the hotspot in a waste storage space inside the FDNPS using the Compton camera. We also created the 3D structural model of the waste storage space in the virtual space by using the photogrammetry and superimposed the image of the hotspot on the 3D structural model. Furthermore, we are developing a system that imports the 3D structural model including the image of the hotspot into the virtual reality and allows workers to experience the actual working environment. We believe that these visualization techniques help workers to easily recognize the hotspot at the actual working environment and to decrease their own exposure. These visualization techniques are also effective for planning decontamination and eventually accelerating the decommissioning of the FDNPS.

口頭

Development and demonstration of small compact radiation imaging system

佐藤 優樹

no journal, , 

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown after the occurrence of a large tsunami caused by the Great East Japan Earthquake of March 11, 2011. The radiation distribution measurements inside the FDNPS are indispensable to execute decommissioning tasks. We have conducted the radiation imaging experiment inside the FDNPS building using the compact Compton camera. The high-dose contamination (up to 3.5 mSv/h) was visualized using the Compton camera in the turbine building of Unit 3 of the FDNPS. We also created a three-dimensional (3D) radiation distribution map inside the turbine building by integrating the radiation image obtained by the Compton camera into the point cloud data of the experimental environment acquired using the scanning laser range finder. In addition, we introduce the photogrammetry technique to create the 3D structural model of the experimental environment. The image of the radioactive hotspot is superimposed on the 3D structural model of inside the reactor building of Unit 1 of the FDNPS created using the photogrammetry. In the presentation, our recent study about the radiation imaging technology for measurements of the distribution of radioactive substances inside the FDNPS is discussed.

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