Monte Carlo modeling for perfusion monitoring

A Monte Carlo method was developed to model light transport through multi-layered tissue with the application focused on the development of an implantable perfusion monitor. The model was developed and then verified experimentally with a micro perfusion phantom. The program modeled a three-layer (tissue, capillary bed, tissue) scenario to investigate the source-detector separation effects for an implantable sensor. The Monte Carlo code was used specifically to model the effects of absorption and scattering properties of the surrounding tissue, the hemoglobin concentration in the middle layer, the ratio of thickness of the capillary layer to the first layer, and the probe-source separation distance on the propagation of the light through the tissue. The model was verified experimentally, using a simple in vitro system with optical source and detector fibers separated at various distances. The model was also used to investigate fluctuations in luminance as a result of hemoglobin concentrations and the response of the system to various wavelengths. The model was helpful for an ongoing project to develop an implantable perfusion monitor for transplanted organs or skin flaps.