Monte-carlo Simulation of Light Propagation considering Characteristic of Near-infrared LED and Evaluation on Tissue Phantom

Currently, there are many techniques to measure subcutaneous fat of skin layers on clinical fields. Among many kinds of methods to measure subcutaneous fat, an optical method has especially many advantages. Moreover, it is appropriate to use during a surgery like liposuction. To implement the optical method, a simulation by LEDs is frequently performed. In the field of optics, there are several methods to simulate diffuse light, such as Monte-carlo simulation. Although the basic Monte-carlo simulation for light propagation is only based on using beam typed light source, we consider characteristics of a LED source and suggest a method to simulate the light propagation by the LED source. To make the Monte-carlo simulation for a LED source, we modify the step of initializing photon in the simulation. First, we expand an initial area launching photons. Second, we apply stochastically the incident angle of photons. Third, we make the method performed differently according a contact area between LED source and turbid medium. Finally, we check the verification of our simulation compared with experimental results. The correlation coefficient between the simulation and the experimental results is 0.9771. In this study, for developments of devices to measure the subcutaneous fat using a LED source, we make the valid method to simulate diffuse light. In the future, we will develop the equipment to measure a fat thickness and an irregularity of it during liposuction surgery, based on the simulation method we proposed. (C) 2013 The Authors. Published by Elsevier B.V.