大鼠创伤性脑水肿模型中近红外光有效检测深度研究

Near Infrared Effective Detection Depth in Mouse Traumatic Brain Edma Model

采用近红外光谱技术实现颅脑损伤的无损监测过程中,存在着检测深度不明确的问题.利用Monte Carlo模拟光子在生物组织中的传输过程,建立有效检测深度模型,对光纤探头在大鼠创伤性脑水肿模型中的有效检测深度规律进行了研究.采用不依赖于模板的阈值分割和窄带水平集分割方法,将大鼠头部MRI图像分为头皮、头骨、脑脊液、灰质和白质五部分,建立真实的大鼠脑组织三维模型,使Monte Carlo仿真结果更加准确.改进复杂组织光场分布仿真的t MCi mg软件,使其能够实时记录光子在组织中的位置和光子被检测器接收时的能量,从而计算出探头在组织中的有效检测深度.分析了不同光源和检测器的中心距、光源芯径对有效检测深度的影响,结果表明光在大鼠脑组织中的有效检测深度小于或者等于光源和检测器中心距的一半,并随光源芯径的增大逐渐增大.建立大鼠脑水肿模型,验证了仿真结果的正确性.研究结果对于无创脑水肿模型的光纤探头的设计和脑水肿区域的判定有着重要的意义.

In the research of mouse traumatic brain edema,the near infrared spectroscopy effective detection depth is not clear.Aiming at that problem,Monte Carlo method was used to simulate the photon distribution in biological tissue.The photon′s effective detection depth was calculated from the photon distribution.The multi-layer model of mouse brain was obtained by the segmentation of MRI.The advanced value segmentation,narrowband level set were used to segment the scalp,the skull,cerebrospinal fluid,gray and white matter from the whole brain MRI.This segmentation method does not depend on templates.The tMCimg software,which is used to simulate the photons′ optical distribution in complex tissues,was modified to record the photons′ position and the photons′ energy used in the calculation of the effective detection depth.The effective detection depth was discussed with the different center distance of source and detector and radius of source.Effective detection depth in tissue is less than or equal to half of the distance source and detector and it increases with the radius of the source.The mouse brain edema model was built to verify the simulation.The result is important to the design of source and detector probe and the detection of the edema region.