Optimization for Brain Activity Monitoring with near Infrared Light in a Four-layered Model of the Human Head

We describe a four-layered model for near infrared light propagation in a human head based on the Monte Carlo method. With the use of three-dimensional voxel-based media discretization, photon migration in the brain is analyzed by both the time-of-flight measurement and the spatial sensitivity profile. In the measurement of brain activity, the selection of light wavelength and the distance between the source and the detector have a great influence on the detected signal. In this study, we compare the detected signals from the detectors with different source-detector spacing at wavelengths of 690 nm, 800 nm and 1300 nm, and find that in our model, the wavelength of 1300 nm is more appropriate for the measurement of brain activity because the signals at 1300 nm get better detection sensitivity and spatial resolution. Source-detector spacing is also optimized. Received 2 April 2013, Accepted 10 May 2013, Scheduled 4 June 2013 * Corresponding author: Sailing He ([email protected]). † These authors contribute equally to this study. 278 Guo, Cai, and He