Performance Test Of A Portable NIR Instrument For Brain Function Imaging

Near-infrared Spectroscopy (NIRS) technology, which can fulfill the real-time and non-invasive in-vivo measurements of blood oxygen metabolizing, was widely used in biomedical field and many equipment and measure means about the technology were developed. Thus, a set of NIRS blood oxygen measure system using three-wave length and continuous wave was designed in our lab. Before this system was applied, we must test the performance of the system with experiment to insure the security, credibility and validity.The content of this paper is, a series of test was carried on, basing on the NIRS blood oxygen system, mainly including the basic performance test of the system and experiment of the model and in the body. We made sure the right scope of the light source power by measuring the system in the P -I characteristic of the light source, and also verify the safety of the system light source. In the dark room, the noise and the long-time stability of the system was carried on .The result showed the stability is good according to the psychology experiment mode. The interference test, including background light interference and between the channels, the experiment proved the interference suffered from the background light and the voltage variety scope is very small, so we can know that interference is very small. Because that system included many detectors, so weather the respond of each channel to changes is the same is very important, when the different district was activated to the same stimulation. The experiment showed that the system had the good consistency to respond between the channels.The detector ability of system was an impossible parameter. Imitating the optical characteristic parameter of the homogeneous biological tissue, make use of Monte Carlo Simulations (MCS) firstly to carry on theoretically, then make use of this system to carry on the actual measurement, we can know that the depth in the homogeneous biological tissue is about 14mm by comparison, the test showed that we can get the information of the HbO2, Hb and HbT change accurately with the system. When set the system into the in clinical application, the NIRS blood oxygen measure system must can adapt to measure in the body. By measuring the forearm blood oxygen concentration change in real-time, observed the light intensity change was in accordance with the blood concentration change in the tissue, showed the validity of system in detecting the blood oxygen characteristic biological tissue.