Effect of tissue optical properties on imaging contrast of optical coherence tomography: Monte-Carlo simulations

In order to understand better the imaging contrast of OCT, Monte Carlo technique is applied to simulate the OCT signal from turbid medium with various optical properties. In the simulation, least scattered photons and multiple scattered photons in relation to the desired target depth are scored separately to show the limit of OCT imaging depth. The least scattered photon is termed as the one that is back scattered from the desired target depth, whereas multiple scattered photons are from depths other than the desired depth. The results show that multiple scattered photons are responsible for the decrease of contrast of the OCT image and their contributions become more significant as the depth increases. The anisotropy parameter of the turbid medium plays a significant role in the OCT imaging contrast. With the scattering coefficient fixed, the higher the g values (i.e. more forward scattering), the deeper the depth of OCT imaging capability, but the lower the OCT signal magnitude. The lower the g value, the more the multiple scattered photons contribute to the OCT signal reducing the imaging capability.