KEIO RESEARCHERS INFORMATION SYSTEM

Career 【 Display / hide 】

Career 【 Display / hide 】

• 1990.04

  -

  1991.03

  日本学術振興会 ,特別研究員

• 1990.10

  -

  1991.03

  慶應義塾大学理工学部電気工学科 ,訪問研究員

• 1991.04

  -

  1993.03

  慶應義塾大学理工学部電気工学科 ,助手

• 1993.04

  -

  1996.03

  慶應義塾大学理工学部 ,専任講師

• 1994.04

  -

  1996.03

  Honorary Lecturer,Department of Medical Physics and Bioengineering,University College London兼日本学術振興会海外 ,特別研究員

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Academic Background 【 Display / hide 】

Academic Background 【 Display / hide 】

• 1986.03

  Keio University, Faculty of Science and Engineering, 電気工学科

  University, Graduated

• 1988.03

  Keio University, Graduate School, Division of Science and Engineeri, 電気工学専攻

  Graduate School, Completed, Master's course

• 1990.09

  Keio University, Graduate School, Division of Science and Engineeri, 電気工学専攻

  Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide 】

Academic Degrees 【 Display / hide 】

• Ph.D, Keio University, Coursework, 1990.09

Research Areas 【 Display / hide 】

Research Areas 【 Display / hide 】

• Biomedical Optics

• Optical and Image Engineering

• Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Measurement engineering (Electronic Measurements)

Books 【 Display / hide 】

Books 【 Display / hide 】

• Application of Near Infrared Spectroscopy in Biomedicine

  OKADA EIJI, Springer, 2013

  Scope: 37-58

• Near infrared spectroscopy

  OKADA EIJI, コロナ社, 2012.02

  Scope: 68

• NIRS -基礎と臨床-

  OKADA EIJI, Hiroshi Kawaguchi, 新興医学出版社, 2012.01

  Scope: 6-14

• 精神疾患とNIRS　光トポグラフィー検査による脳機能イメージング

  OKADA EIJI, 中山書店, 2009.06

  Scope: 31-38

• 電気・電子・情報工学系テキストシリーズ3　電子回路

  高橋進一・岡田 英史, 培風館, 2002.05

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Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Monte Carlo simulation of photon transport in a scattering-dominated medium with a refractive index gradient for acoustic light-guiding

  YAMAMURA N. A. O. T. O., OKADA E. I. J. I., NAKAGAWA K. E. I. I. C. H. I., TAKAGI S. H. U.

  OPTICS CONTINUUM 1 ( 4 ) 846 - 859 2022.04

  • Access to Document (DOI)

• Targeting brain regions of interest in functional near-infrared spectroscopy—Scalp-cortex correlation using subject-specific light propagation models

  Cai L., Nitta T., Yokota S., Obata T., Okada E., Kawaguchi H.

  Human Brain Mapping (Human Brain Mapping)  42 ( 7 ) 1969 - 1986 2021.05

  ISSN  10659471

  　View Summary

  Targeting specific brain regions of interest by the accurate positioning of optodes (emission and detection probes) on the scalp remains a challenge for functional near-infrared spectroscopy (fNIRS). Since fNIRS data does not provide any anatomical information on the brain cortex, establishing the scalp-cortex correlation (SCC) between emission-detection probe pairs on the scalp and the underlying brain regions in fNIRS measurements is extremely important. A conventional SCC is obtained by a geometrical point-to-point manner and ignores the effect of light scattering in the head tissue that occurs in actual fNIRS measurements. Here, we developed a sensitivity-based matching (SBM) method that incorporated the broad spatial sensitivity of the probe pair due to light scattering into the SCC for fNIRS. The SCC was analyzed between head surface fiducial points determined by the international 10–10 system and automated anatomical labeling brain regions for 45 subject-specific head models. The performance of the SBM method was compared with that of three conventional geometrical matching (GM) methods. We reveal that the light scattering and individual anatomical differences in the head affect the SCC, which indicates that the SBM method is compulsory to obtain the precise SCC. The SBM method enables us to evaluate the activity of cortical regions that are overlooked in the SCC obtained by conventional GM methods. Together, the SBM method could be a promising approach to guide fNIRS users in designing their probe arrangements and in explaining their measurement data.

  • Access to Document (DOI)

• Experimental tests of indicators for the degree of validness of the diffusion approximation

  Capart A., Ikegaya S., Okada E., Machida M., Hoshi Y.

  Journal of Physics Communications (Journal of Physics Communications)  5 ( 2 ) 1 - 17 2021

  ISSN  2399-6528

  　View Summary

  The diffusion approximation has been one of the central topics in near-infrared spectroscopy (NIRS). When NIRS measurements are analyzed by the diffusion theory, the measurements must be performed in the diffusive regime. However, since most of past researches have focused on theoretical or qualitative nature of the diffusion approximation, it is not easy to know if each measurement is designed in the diffusive regime. In this paper, we consider the diffusion approximation quantitatively and propose indicators that quantify the degree of validness of the diffusion approximation. The difference between the measurement and diffusion theory can be evaluated with the χ value, ℓ and ℓ norms, and Kullback-Leibler divergence. We conduct a liquid phantom experiment to test the proposed χ value. Moreover, the χ value is further investigated by Monte Carlo simulations. We find the χ value becomes significantly large when measurements are performed in the nondiffusive or transport regime. The proposed indicators similarly work. In particular, the χ value is shown to work as an indicator which evaluates the degree of validness of the diffusion approximation. These indicators are general and can be used for different numerical, experimental, and clinical measurements in NIRS. 2 1 2 2 2 2 2

  • Access to Document (DOI)

• Correlating functional near-infrared spectroscopy with underlying cortical regions of 0-, 1-, and 2-year-olds using theoretical light propagation analysis

  Cai Lin, Okada Eiji, Minagawa Yasuyo, Kawaguchi Hiroshi

  NEUROPHOTONICS 8 ( 2 ) 025009 2021

  ISSN  2329-423X

  • Access to Document (DOI)

• In situ estimation of optical properties of rat and monkey brains using femtosecond time-resolved measurements

  Hoshi Y., Tanikawa Y., Okada E., Kawaguchi H., Nemoto M., Shimizu K., Kodama T., Watanabe M.

  Scientific Reports (Scientific Reports)  9 ( 1 ) 9165 2019.12

  ISSN  2045-2322

  　View Summary

  An accurate knowledge of tissue optical properties (absorption coefficients, μ , and reduced scattering coefficients, μ ’) is critical for precise modeling of light propagation in biological tissue, essential for developing diagnostic and therapeutic optical techniques that utilize diffusive photons. A great number of studies have explored the optical properties of various tissue, and these values are not known in detail due to difficulties in the experimental determination and significant variations in tissue constitution. Especially, in situ estimates of the optical properties of brain tissue, a common measurement target in optical imaging, is a challenge because of its layer structure (where the thin gray matter covers the white matter). Here, we report an approach to in situ estimates of the μ and μ ’ of the gray and white matter in living rat and monkey brains by using femtosecond time-resolved measurements and Monte Carlo simulation. The results demonstrate that the μ of the gray matter is larger than that of the white matter, while there was no significant difference in the μ ’ between the gray and white matter. The optical properties of the rat brain were very similar to those of the monkey brain except for the μ of the gray matter here. a s a s a s a

  • Access to Document (DOI)

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Papers, etc., Registered in KOARA 【 Display / hide 】

Papers, etc., Registered in KOARA 【 Display / hide 】

• DMCシンポジウム2022「デジタルの本質とはなにか : メタバースに向かう中で考える」

  Okada, Eiji

  DMC review Keio University (慶應義塾大学デジタルメディア・コンテンツ統合研究センター)  9/10 ( 1 ) 110 - 147 2023.03

  ISSN  21883424

• Experimental validation of diffuse optical imaging using high-density probe configuration by the dynamic head phantom

  Okada, Eiji

  科学研究費補助金研究成果報告書 2018

• Multimodal imaging system for biological function measurements by using diffusion light

  Okada, Eiji

  科学研究費補助金研究成果報告書 2009

Reviews, Commentaries, etc. 【 Display / hide 】

Reviews, Commentaries, etc. 【 Display / hide 】

• 拡散光イメージングと脳機能計測への応用

  OKADA EIJI

  光アライアンス 27 ( 2 ) 12 - 17 2016.02

  Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media), Single Work

• 拡散光イメージングと脳機能計測への応用

  OKADA EIJI

  光技術コンタクト 53 ( 7 ) 16 - 23 2015.07

  Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media), Joint Work

• Technical trend of noninvasive brain-function imaging by near-infrared spectroscopy

  OKADA EIJI, KAZUKI KURIHARA, HIROSHI KAWAGUCHI, TAKAYUKI OBATA, YOKO HOSHI

  日本レーザー医学会誌 36 ( 2 ) 187 - 194 2015.07

  Article, review, commentary, editorial, etc. (scientific journal), Joint Work

Presentations 【 Display / hide 】

Presentations 【 Display / hide 】

• 上腕圧迫時の分光反射スペクトル変化に基づく皮膚内実効光路長の波長依存性の測定

  佐藤 里奈，白井 大貴，加藤 陽，岡田 英史

  日本光学会年次学術講演会 Optics & Photonics Japan 2017 (東京) , 

  2017.10

  , 

  Poster presentation

• Effect of broadened probing region on functional areas measured by a probe pair of fNIRS

  NITTA TOMONORI, TSUYUKI RYOHEI, KAWAGUCHI HIROSHI, OKADA EIJI

  European Conference on Biomedical Optics 2017 (Munich, Germany) , 

  2017.06

  , 

  Poster presentation

• Solid phantom mimicking localized absorption change in the brain and scalp for near infrared imaging

  HAYABUSA KOKI, OKADA EIJI

  European Conference on Biomedical Optics 2017 (Munich, Germany) , 

  2017.06

  , 

  Oral presentation (general)

• Influence of superficial tissue thickness on noninvasive detection of fluorescent probe in the brain

  ASAI KOTA,KAWAGUCHI HIROSHI, OBATA TAKAYUKI, OKADA EIJI

  European Conference on Biomedical Optics 2017 (Munich, Germany) , 

  2017.06

  , 

  Oral presentation (general)

• Light propagation analysis for fluorescence measurements of a molecular probe in the brain

  ASAI KOTA, TOGASHI TAKUYA, OKADA EIJI

  Biomedical Imaging and Sensing Conference 2017 (Yokohama, Japan) , 

  2017.04

  , 

  Poster presentation

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

Research Projects of Competitive Funds, etc. 【 Display / hide 】

• ダイナミックファントムによる高密度プローブ拡散光イメージング法の実証実験

  2016.04

  -

  2019.03

  MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Principal investigator

Awards 【 Display / hide 】

Awards 【 Display / hide 】

• 第10回日本ME学会秋季大会 若手研究論文優秀賞

  岡田 英史, 1996.10, 日本ME学会

• 第15回丹羽記念賞

  岡田 英史, 1992.02

  Type of Award： Award from publisher, newspaper, foundation, etc.

• 日本ME学会 科学新聞賞学術奨励賞

  岡田 英史, 1990.05, 日本ME学会

• IEEE Engineering in Medicine and Biology Society Student Paper Award

  岡田 英史, 1989.11, IEEE

• 安藤博記念 学術奨励賞

  岡田 英史, 1989.06

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Courses Taught 【 Display / hide 】

Courses Taught 【 Display / hide 】

• RECITATION IN ELECTRONICS AND INFORMATION ENGINEERING

  2024

• LABORATORIES IN ELECTRONICS AND INFORMATION ENGINEERING(2)

  2024

• INDEPENDENT STUDY ON INTEGRATED DESIGN ENGINEERING

  2024

• GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 2

  2024

• GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 1

  2024

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Courses Previously Taught 【 Display / hide 】

Courses Previously Taught 【 Display / hide 】

• Information Optics and Optical Measurements

  Keio University

  2018.04

  -

  2019.03

  , 

  Lecture, Within own ｆaculty

• コンピュータシミュレーション同実習／数値解析

  Keio University

  2014.04

  -

  2015.03

  , 

  Lecture

• 総合デザイン工学特別研究第2

  Keio University

  2014.04

  -

  2015.03

  , 

  Full academic year

• 総合デザイン工学特別研究第1

  Keio University

  2014.04

  -

  2015.03

  , 

  Full academic year

• 総合デザイン工学課題研究

  Keio University

  2014.04

  -

  2015.03

  , 

  Full academic year

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Social Activities 【 Display / hide 】

Social Activities 【 Display / hide 】

• 文部科学省　科学技術政策研究所　科学技術動向研究センター

  2012.04

  -

  2014.03

• 一般財団法人光産業技術振興協会 光技術動向調査委員会

  2011.04

  -

  2014.03

• 一般社団法人　電子情報技術産業協会 医用光生体計測に関する国際標準化対応委員会

  2011.04

  -

  2014.03

• 独立行政法人新エネルギー・産業技術総合開発機構

  2011.01

  -

  2012.03

• 日本学術会議国際光学委員会（ICO）分科会光量子化学技術連携委員会

  2010.03

  -

  2011.03

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Memberships in Academic Societies 【 Display / hide 】

Memberships in Academic Societies 【 Display / hide 】

• 日本ヒト脳機能マッピング学会, 

  2012.08

  -

  Present

• 日本シミュレーション学会, 

  2012.06

  -

  Present

• International Conference on Modeling and Simulation Technology, 

  2011.01

  -

  2011.10

• 応用物理学会日本光学会年次学術講演会OPJ2010プログラム委員会, 

  2010.03

  -

  2010.11

• 応用物理学会JJAP編集委員会, 

  2009.04

  -

  2013.03

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Committee Experiences 【 Display / hide 】

Committee Experiences 【 Display / hide 】

• 2017.04

  -

  2017.11

  OPJ2017実行委員長, 日本光学会

• 2016.10

  -

  2017.06

  Program Committee Member, European Conference on Biomedical Optics

• 2016.07

  -

  2017.08

  Program Committee, Category Chair, The 24th Congress of the International Commission for Optics

• 2016.04

  -

  2016.11

  OPJ2016 副実行委員長, 日本光学会

• 2016.02

  -

  2019.12

  International Advisory Board for Physics in Medicine and Biology, Institute of Physics

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