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Measurement of the Optical Properties of the Adult Human Head with Spatially Resolved Spectroscopy and Changes of Posture

  • Terence S. Leung
  • Clare E. Elwell
  • Ilias Tachtsidis
  • Julian R. Henty
  • David T. Delpy
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 540)

Abstract

Absolute optical properties (i.e., absorption and reduced scattering coefficients, µ a and µ s ’) of human tissues such as the head, calf and arm have been measured using near-infrared (NIR) phase1, time2 or spatially3 resolved spectroscopy (SRS) systems. While a simple continuous-wave (CW) system can measure Δµ a , absolute µ a cannot be easily measured because of the complex geometry in which measurements are made in tissues. It has been shown that the SRS technique can be used to calculate a scaled absolute µ a , i.e. µ s ’ µ a where µ s ’ is considered as a time-invariant scaling factor4. This paper suggests a way to use a commercially available spectrometer, namely the NIRO-300 (Hamamatsu KK.) which has both CW and SRS capabilities, to calibrate an absolute µ a based on the changes of µ a (i.e., Δµ a , calculated from the CW data and a modified Beer-Lambert law) and the scaled µ a (i.e., µ s ’ µ a calculated from the SRS data). Using changes of posture from the supine to the head up position, the absolute optical properties of 15 adult human heads were calculated. Issues of errors due to the inhomogeneity in real tissues and methods to minimise them are also discussed.

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Copyright information

© Springer Science+Business Media New York 2003

Authors and Affiliations

  • Terence S. Leung
    • 1
  • Clare E. Elwell
    • 1
  • Ilias Tachtsidis
    • 1
  • Julian R. Henty
    • 1
  • David T. Delpy
    • 1
  1. 1.Department of Medical Physics & BioengineeringUniversity College LondonLondonUK

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