Introduction
Influence of the pulse wave on the volume of brain and its optical parameters
![](https://academic.hep.com.cn//article\2017\2095-2759/2095-2759-10-3-287/thumbnail/foe-17023-mj-fig1.jpg)
Fig.1 Simplified diagram illustrating the effects of the pulse wave during particular phases of cardiac cycle on the width of the SAS, cerebral arteries and arterioles (indicated by different radii of the wheels), amount of blood in the skin (indicated by dot density), and the transmission of near-infrared radiation in the outer-head tissue layers, where 1, 2, 3, and 4 represent the skin, skull bone, SAS, and surface of the brain covered with cerebral arteries and arterioles (indicated by circles), respectively. S denotes the near-infrared source, PD denotes the proximal detector (used to compensate for a changes of skin absorption), and DD denotes the distal detector (used to detect near-infrared radiation propagating in the SAS or in the brain) [1] |
Numerical modeling of transmission of near-infrared radiation in outer-head tissue layers
Tab.1 Optical parameters of tissues of the head used for numerical modeling [14] |
tissue | thickness /mm | absorption coefficient /mm−1 | reduced scattering coefficient /mm−1 |
---|---|---|---|
skin | 3 | 0.013 | 1.7 |
bone – external compact lamina | 1 | 0.0242 | 0.88 |
bone – spongious layer | 2.5 | 0.01627 | 0.59268 |
bone – internal compact lamina | 1.5 | 0.0242 | 0.88 |
SAS | 0–3.5 | 0.001 | 0.001 |
brain | 10 | 0.037 | 2.0 |