Okada, Eiji

写真a

Affiliation

President and Vice-Presidents (Mita)

Position

Vice-President

Related Websites

External Links

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

Academic Degrees 【 Display / hide

  • Ph.D, Keio University, Coursework, 1990.09

 

Research Areas 【 Display / hide

  • Optical and Image Engineering

  • Biomedical Optics

  • Measurement engineering (Electronic Measurements)

 

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

  • 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.

  • 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

     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

  • Non-contact acquisition of brain function using a time-extracted compact camera

    Ando T., Nakamura T., Fujii T., Shiono T., Nakamura T., Suzuki M., Anzue-Satoi N., Narumi K., Watanabe H., Korenaga T., Okada E., Inoue Y.

    Scientific Reports (Scientific Reports)  9 ( 1 )  2019.12

     View Summary

    A revolution in functional brain imaging techniques is in progress in the field of neurosciences. Optical imaging techniques, such as high-density diffuse optical tomography (HD-DOT), in which source-detector pairs of probes are placed on subjects’ heads, provide better portability than conventional functional magnetic resonance imaging (fMRI) equipment. However, these techniques remain costly and can only acquire images at up to a few measurements per square centimetre, even when multiple detector probes are employed. In this study, we demonstrate functional brain imaging using a compact and affordable setup that employs nanosecond-order pulsed ordinary laser diodes and a time-extracted image sensor with superimposition capture of scattered components. Our technique can simply and easily attain a high density of measurement points without requiring probes to be attached, and can directly capture two-dimensional functional brain images. We have demonstrated brain activity imaging using a phantom that mimics the optical properties of an adult human head, and with a human subject, have measured cognitive brain activation while the subject is solving simple arithmetical tasks.

  • 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 )  2019.12

     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

  • Time-domain diffuse optical tomography with l<inf>p</inf> sparsity regularization for thyroid cancer imaging

    Okawa S., Mimura T., Fujii H., Kawaguchi H., Tanikawa Y., Machida M., Okada E., Hoshi Y.

    Optics InfoBase Conference Papers (Optics InfoBase Conference Papers)  Part F142-ECBO 2019 2019

    ISSN  9781557528209

     View Summary

    Diffuse optical tomography (DOT) images the distribution of the optical properties, such as the absorption and scattering coefficients, via the image reconstruction from the light intensities measured at the surface of the biological medium. The changes in the optical properties reflect the conditions of the tissues. Therefore, DOT image can provide the information which is not obtained from the other modalities and is useful for medical diagnoses. In this study, the application of the DOT to thyroid cancer diagnosis was investigated. The ultrasound technique is usually carried out for the thyroid cancer diagnosis. It is, however, difficult to distinguish follicular carcinoma from adenoma of thyroid. The optical properties may be helpful for the diagnosis. The image reconstruction algorithm employing the regularization minimizing l -norm (0 < p < 2) of the reconstructed image was developed. The image was reconstructed from the time-resolved measurement data. The numerical simulations of the image reconstruction were tried. The numerical simulation demonstrated that the developed algorithm was able to image the changes in the optical properties in the medium. Additionally, the image reconstruction of the numerical neck phantom was simulated. The thyroid cancer region was reconstructed successfully. It was demonstrated that the developed algorithm had the possibility to image thyroid cancer. p

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Papers, etc., Registered in KOARA 【 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

    Introduction and explanation (commerce magazine), 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

    Introduction and explanation (commerce magazine), 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

    Introduction and explanation (scientific journal), Joint Work

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 (general)

  • 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 (general)

  • 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 (general)

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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, 岡田 英史, Grant-in-Aid for Scientific Research (C), Principal Investigator

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: Awards of Publisher, Newspaper Company and Foundation

  • 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

  • RECITATION IN ELECTRONICS AND INFORMATION ENGINEERING

    2021

  • NUMERICAL ANALYSIS

    2021

  • LABORATORIES IN ELECTRONICS AND INFORMATION ENGINEERING(2)

    2021

  • INDEPENDENT STUDY ON INTEGRATED DESIGN ENGINEERING

    2021

  • GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 2

    2021

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Courses Previously Taught 【 Display / hide

  • Information Optics and Optical Measurements

    Keio University, 2018, Major subject, Lecture, Within own faculty

  • 応用数学

    Keio University, 2014, Autumn Semester, Major subject, Lecture

  • 電気電子工学実験第2

    Keio University, 2014, Autumn Semester

  • 電気電子工学実験第1

    Keio University, 2014, Spring Semester

  • Information Optics and Optical Measurements

    Keio University, 2014, Spring Semester, Major subject, Lecture, Within own faculty

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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
    -
    Present

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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
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    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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