Partial optical path length in the scalp in subject-specific head models for multi-distance probe configuration of near infrared spectroscopy

2018 ◽  
Author(s):  
Taku Yanagisawa ◽  
Eiji Okada ◽  
Hiroshi Kawaguchi ◽  
Takayuki Obata
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Path Length ◽  
Near Infrared ◽  
Optical Path Length ◽  
Optical Path ◽  
Subject Specific

Estimation of partial optical path length in the brain in subject-specific head models for near-infrared spectroscopy

2016 ◽  
Vol 23 (2) ◽  
pp. 316-322 ◽  
Author(s):  
Kotaro Nakamura ◽  
Kazuki Kurihara ◽  
Hiroshi Kawaguchi ◽  
Takayuki Obata ◽  
Hiroshi Ito ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Path Length ◽  
Near Infrared ◽  
Optical Path Length ◽  
Optical Path ◽  
Subject Specific ◽  
The Brain

Measurement of Optical Path Length for Cerebral Near-Infrared Spectroscopy in Newborn Infants

1990 ◽  
Vol 12 (2) ◽  
pp. 140-144 ◽  
Author(s):  
J.S. Wyatt ◽  
M. Cope ◽  
D.T. Delpy ◽  
P. van der Zee ◽  
S. Arridge ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Path Length ◽  
Near Infrared ◽  
Newborn Infants ◽  
Optical Path Length ◽  
Optical Path

scholarly journals Measurement of Cranial Optical Path Length as a Function of Age Using Phase Resolved Near Infrared Spectroscopy

1996 ◽  
Vol 39 (5) ◽  
pp. 889-894 ◽  
Author(s):  
Arlene Duncan ◽  
Judith H Meek ◽  
Matthew Clemence ◽  
Clare E Elwell ◽  
Penny Fallon ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Path Length ◽  
Near Infrared ◽  
Optical Path Length ◽  
Optical Path

scholarly journals Quantification in tissue near–infrared spectroscopy

1997 ◽  
Vol 352 (1354) ◽  
pp. 649-659 ◽  
Author(s):  
D. T. Delpy ◽  
M. Cope
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Path Length ◽  
Near Infrared ◽  
Modulation Depth ◽  
Light Attenuation ◽  
Complex Function ◽  
Optical Path Length ◽  
Optical Path ◽  
Light Transport

In near–infrared spectroscopy (NIRS) of tissue, light attenuation is due to: (i) absorption from chromophores of fixed concentration, (ii) absorption from chromophores of variable concentration, and (iii) light scatter. NIRS is usually concerned with trying to quantify the concentrations of chromophores in category (ii), in particular oxy– and deoxyhaemoglobin (HbO 2 and Hb) and cytochrome oxidase. In the absence of scatter the total light absorption in the medium is a linear sum of that due to each chromophore. In a scattering medium like tissue, this linear summation is distorted because the optical path length at each wavelength may differ. This distorted spectrum is then superimposed upon a further wavelength–dependent attenuation arising from light loss due to scatter, which is a complex function of the tissue absorption and scattering coefficients ( μ a and μ s ), scattering phase function, and tissue and measurement geometry. Consequently, quantification of NIRS data is difficult. Over the past 20 years many differing approaches to quantification have been tried. The development of methods for measuring optical path length in tissue initially enabled changes in concentration to be quantified, and subsequently methods for absolute quantification of HbO 2 and Hb were developed by correlating NIRS changes with an independent measurement of arterial haemoglobin saturation. Absolute determination of tissue optical properties, however, requires additional information over and above the detected intensity at the tissue surface, which must then be combined with a model of light transport to derive μ a and μ s . The additional data can take many forms, e.g. the change in intensity with distance, the temporal dispersion of light from an ultrashort input light pulse, or phase, and modulation depth changes of intensity–modulated light. All these approaches are now being actively pursued with considerable success. However, all the approaches are limited by the accuracy of the light transport models, especially in inhomogeneous media.

Non-Traditional Applications of near Infrared Spectroscopy Based on the Optical Characteristic Models for a Biological Material Having Cellular Structure

1998 ◽  
Vol 6 (1) ◽  
pp. 41-46 ◽  
Author(s):  
Satoru Tsuchikawa
Keyword(s):  
Biological Material ◽  
Path Length ◽  
Cellular Structure ◽  
Process Model ◽  
Near Infrared ◽  
Traditional Approach ◽  
Nir Spectroscopy ◽  
Optical Path Length ◽  
Optical Path ◽  
The Mean

Non-destructive measurements, based on near infrared (NIR) spectroscopy, on biological material with a cellular structure like wood require a non-traditional approach. We have developed new concepts to model the optical properties of a sample having cellular structure, for the illumination conditions of the spectrometer available to us. A set of optical models, which consisted of the directional characteristics models, the light-path models and the equivalent surface roughness model was proposed to clarify the behaviour of light propagation in a wood sample. Furthermore, the mean optical path length, which was derived by incorporating the nth power cosine model of radiant intensity into the diffusion process model in consideration of the parallel beam component of incident light, was calculated. By introducing the concept of equivalent sample thickness, compatible with the mean optical path length, into the Kubelka–Munk theory, generalised input/output equations for radiation were constructed. In this non-traditional application of NIR spectroscopy, these optical concepts make it possible to analyse both the physical condition and chemical composition of a biological material with a cellular structure.

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