SUNFEST REU Program Remote Cognosensors: Developing an NIR Imaging Model to Map Brain Function

Near-infrared (NIR) imaging has provided new insight into optical imaging of human tissue. The purpose of this study is to develop an NIR imaging system that could potentially be used to study cognitive function by measuring the optical parameters (μa and μs`) of the human prefrontal cortex. The desired system should be a remote sensing system that does not need direct contact with the subject. It should also be able to work over a distance of 50 cm to 2 m from the subject. This study presents a method of remote sensing via a time resolved spectroscopy approach. Two methods of analysis are used: a single photon counting (SPC) method; and the second being a series of gated integrating circuits (Box Car). System design and initial results are shown for both systems. Actual photon migration patterns, from which values of μa are calculated, were obtained via the SPC method over a distance of 60 cm. Also, experimental results demonstrating pulse shaping are shown from the Box Car system. Finally, noise level reduction in the SPC method is taken into consideration, along with an option for achieving correct Box Car gate timing.