Determining changes in NIR absorption using a layered model of the human head.
A theoretical approach is presented to determine absorption changes in different compartments of a layered structure from distributions of times of flight of photons. In addition resulting changes in spatial profiles of time-integrated intensity and mean time of flight are calculated. The capability of a single-distance, time-domain method to determine absorption changes with depth resolution is tested on a layered phantom. We apply this method to in vivo measurements on the human head (motor stimulation, Valsalva manoeuvre) and introduce a small-sized time-domain experimental set-up suitable for bedside monitoring.
Steinbrink
J
J
Physikalisch-Technische Bundesanstalt, Berlin, Germany.
Wabnitz
H
H
Obrig
H
H
Villringer
A
A
Rinneberg
H
H
D001921:Brain; D003198:Computer Simulation; D006257:Head; D006801:Humans; D009010:Monte Carlo Method; D009043:Motor Activity; D019047:Phantoms, Imaging; D017785:Photons; D019265:Spectroscopy, Near-Infrared; D014636:Valsalva Maneuver