Continuous wave near-infrared spectroscopy (CW-NIRS) can be used to measure cerebral activity because it is noninvasive, simple and portable. However, the performance of the continuous wave near-infrared spectroscopy is distorted by the presence of extracerebral layer. Change of optical parameters in gray matter layer will then be inappropriately converted into the brain activity response. In the current study, a five-layer structure model constitute of scalp, skull, cerebrospinal fluid, gray matter and white matter, have been applied to fabricate human brain tissue. The phantom is made by the mixture of the Intralipid, India ink and agar. The optical parameters of gray matter layer can be flexibly adjusted to simulate the change of the deep brain tissue. The near infrared optical measurement system was designed to detect the changes in the absorption coefficients of the gray matter and quantitative analyze the influence of the extracerebral layers. Monte Carlo technique for the equivalent multi-layered brain tissue models is then performed to compensate partial volume effect introduced by the extracerebral layers. The results of the experiments suggested that the extracerebral layers influence the measurement and the influence of the extracerebral layers can be suppressed by correcting partial volume effect using Monte Carlo simulations.

连续波近红外光谱（CW-NIRS）可用于测量大脑活动，因为它无创、简单且便携。然而，连续波近红外光谱的性能因脑外层的存在而失真。灰质层光学参数的变化将不适当地转化为大脑活动反应。目前的研究中，由头皮、头骨、脑脊液、灰质和白质组成的五层结构模型已被应用于制造人脑组织。该模型由英脱利匹特、印度墨水和琼脂的混合物制成。可以灵活调节灰质层的光学参数，模拟深部脑组织的变化。设计近红外光学测量系统来检测灰质吸收系数的变化并定量分析脑外层的影响。然后对等效多层脑组织模型进行蒙特卡罗技术，以补偿脑外层引入的部分体积效应。实验结果表明，脑外层影响测量，并且可以通过使用蒙特卡罗模拟校正部分体积效应来抑制脑外层的影响。