Monte Carlo investigation of separation of two absorbers in topographic image

Near infrared topographic imaging is an effective instrument to image brain-cortex activity. The image is reconstructed by changes in light intensity detected with multi-channel source-detector pairs. However, light scattering in tissue prevents us from improving the spatial resolution of the reconstructed image, hence it is important to evaluate the effect of scattering on the spatial resolution of the reconstructed image. In this study, separation of two absorbers in topographic image is investigated by Monte Carlo simulation to evaluate the spatial resolution of topographic imaging. Because of heterogeneity of tissue, especially presence of low scattering CSF layer affects the light propagation in the adult brain. The adult head model consists of three layers including a low scattering medium. In case where the separation of two absorbers is greater than the distance between adjacent measurment points, the two absorbers can be separated in the topographic image.