Okada, Eiji

写真a

Affiliation

President and Vice-Presidents (Mita)

Position

Vice-President

Related Websites

External Links
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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 】

  • 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

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Academic Degrees 【 Display / hide 】

  • Ph.D, Keio University, Coursework, 1990.09

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Research Areas 【 Display / hide 】

  • Biomedical Optics

  • Optical and Image Engineering

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

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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 】

  • Monte Carlo modeling of photoacoustic guided technique in scattering media

    Arisu J., Yamamura N., Nakagawa K., Takagi S., Okada E.

    Proceedings of SPIE - The International Society for Optical Engineering 12628 2023

    ISSN  0277786X

    　View Summary

    The photoacoustic guided (PAG) technique can noninvasively increase light penetration and localization in deep tissue. The mechanism of the PAG technique is considered to be a pressure dependent refractive index change caused by acoustic wave that produces a virtual waveguide, but it is still a highly controversial issue. In this study, light propagation in the models with the PAG region was calculated by a Monte Carlo simulation. We assumed that the change in the refractive index or anisotropy factor of scattering in the PAG region contributes to the light guiding effect. Both the refractive index and anisotropy factor heterogeneities increase the photon density in the PAG region of the deep tissue part. The effect of localization of the photon density in the PAG region with the anisotropy factor heterogeneity is less significant compared to that with the refractive index heterogeneity.

  • Influence of the heterogeneity of extracerebral tissues on scalp-cortex correlation of fNIRS for infants

    Tachikawa R., Okada E.

    Proceedings of SPIE - The International Society for Optical Engineering 12628 2023

    ISSN  0277786X

    　View Summary

    For the prediction of the scalp-cortex correlation (SCC), it is important to consider the influence of the extracerebral tissues on light propagation in the brain. The three-layered infant head models in which the scalp, skull, and cerebrospinal fluid (CSF) are combined as a homogeneous tissue are constructed in order to investigate the influence of the heterogeneity of the thin extracerebral tissues on the prediction of the SCC of infants. The spatial sensitivity profile in the brain calculated by the three-layered model is less broadened than that by the ordinary five-layered model due to the lack of the low scattering CSF layer. However, the influence of the heterogeneity of the extracerebral tissues on the SCC of infants is less significant than that of an adult. The three-layered head model is practically useful to predict the acceptable SCC of the functional near infrared spectroscopy measurements of infants.

  • 3D-printed head surface model of a standard brain template for scalp-cortex correlation of fNIRS

    Kaneko T., Okada E.

    Proceedings of SPIE - The International Society for Optical Engineering 12608 2023

    ISSN  0277786X

    　View Summary

    The scalp-cortex correlation (SCC) is important for the brain activity measurements by functional near-infrared spectroscopy. A physical head surface model was manufactured to accurately determine the probe positions mounted on the probe holder attached to the head. The coordinates of the probe positions measured in the physical space were mapped to the surface of the virtual head model. The light propagation in the virtual head model was calculated to obtain the spatial sensitivity profile and normalized partial optical path length for the evaluation of the SCC.

  • 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

    　View Summary

    Acoustic light waveguides use a technology that employs acoustic waves to create pressure-dependent refractive index distribution and guide light deep into biological tissue similar to an optical fiber. The method by which acoustic optical waveguides increase light transmission in biological tissues occurring inside scattering-dominated medium has not been clarified. To understand the phenomena occurring inside the scattering-dominated medium, we performed Monte Carlo simulations of photon transport in acoustic optical waveguides. The findings indicate that the larger the change in the refractive index in the scattering-dominated media, the greater the effect of photon confinement. In addition, as the refractive index gradient was increased, the near-field internal fluence was found to be greatly enhanced. The transition depth, which indicates the region where the internal fluence is enhanced by the refractive index gradient, was determined as a function of the radius at which the refractive index change is given.

  • 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.

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

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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

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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 】

  • 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

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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 】

  • SEMINAR IN ELECTRONICS AND INFORMATION ENGINEERING(1)

    2025

  • RECITATION IN ELECTRONICS AND INFORMATION ENGINEERING

    2025

  • LABORATORIES IN ELECTRONICS AND INFORMATION ENGINEERING(2)

    2025

  • INDEPENDENT STUDY ON INTEGRATED DESIGN ENGINEERING

    2025

  • GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 2

    2025

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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 】

  • 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 】

  • 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 】

  • 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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