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Journal of Biomedical Optics • Open Access

Performance assessment of time-domain optical brain imagers, part 1: basic instrumental performance protocol

Paper Abstract

Performance assessment of instruments devised for clinical applications is of key importance for validation and quality assurance. Two new protocols were developed and applied to facilitate the design and optimization of instruments for time-domain optical brain imaging within the European project nEUROPt. Here, we present the “Basic Instrumental Performance” protocol for direct measurement of relevant characteristics. Two tests are discussed in detail. First, the responsivity of the detection system is a measure of the overall efficiency to detect light emerging from tissue. For the related test, dedicated solid slab phantoms were developed and quantitatively spectrally characterized to provide sources of known radiance with nearly Lambertian angular characteristics. The responsivity of four time-domain optical brain imagers was found to be of the order of 0.1  m2 sr. The relevance of the responsivity measure is demonstrated by simulations of diffuse reflectance as a function of source-detector separation and optical properties. Second, the temporal instrument response function (IRF) is a critically important factor in determining the performance of time-domain systems. Measurements of the IRF for various instruments were combined with simulations to illustrate the impact of the width and shape of the IRF on contrast for a deep absorption change mimicking brain activation.

Paper Details

Date Published: 14 August 2014
PDF: 12 pages
J. Biomed. Opt. 19(8) 086010 doi: 10.1117/1.JBO.19.8.086010
Published in: Journal of Biomedical Optics Volume 19, Issue 8
Show Author Affiliations
Heidrun Wabnitz, Physikalisch-Technische Bundesanstalt (Germany)
Dieter R. Taubert, Physikalisch-Technische Bundesanstalt (Germany)
Mikhail Mazurenka, Physikalisch-Technische Bundesanstalt (Germany)
Oliver Steinkellner, Physikalisch-Technische Bundesanstalt (Germany)
Alexander Jelzow, Physikalisch-Technische Bundesanstalt (Germany)
Rainer Macdonald, Physikalisch-Technische Bundesanstalt (Germany)
Daniel Milej, Institute of Biocybernetics and Biomedical Engineering (Poland)
Piotr Sawosz, Institute of Biocybernetics and Biomedical Engineering (Poland)
Michał Kacprzak, Institute of Biocybernetics and Biomedical Engineering (Poland)
Adam Liebert, Institute of Biocybernetics and Biomedical Engineering (Poland)
Robert Cooper, Univ. College London (United Kingdom)
Jeremy Hebden, Univ. College London (United Kingdom)
Antonio Pifferi, Politecnico di Milano (Italy)
Istituto di Fotonica e Nanotecnologie (Italy)
Andrea Farina, Istituto di Fotonica e Nanotecnologie (Italy)
Politecnico di Milano (Italy)
Ilaria Bargigia, Istituto Italiano di Tecnologia (Italy)
Politecnico di Milano (Italy)
Davide Contini, Politecnico di Milano (Italy)
Matteo Caffini, Politecnico di Milano (Italy)
Lucia Zucchelli, Politecnico di Milano (Italy)
Lorenzo Spinelli, CNR-Istituto di Fotonica e Nanotecnologie (Italy)
Rinaldo Cubeddu, Politecnico di Milano (Italy)
CNR-Istituto di Fotonica e Nanotecnologie (Italy)
Alessandro Torricelli, Politecnico di Milano (Italy)

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