Invasion depth estimation of gastric cancer in early stage using circularly polarized light scattering: Phantom studies

Abstract

Depolarization of circularly polarized light due to multiple scattering in turbid media provides size distributions of scatterer. Applied it to the biological tissues as turbid media, scatters correspond to cell nuclei, which is abnormally grown in cancerous tissues. Therefore, the invasion depth of early-staged cancer can be estimated by comparisons of circular polarization of scattered light. In this study, we fabricated the optical phantoms made of resin and polystyrene beads to verify this technique by systematic experiments. The single-layered phantoms containing only one size of beads exhibits uniform monodispersed scattering media. Polarization images taken by a circular polarization imaging camera show systematically changes to the numerical density of scatters. Healthy and cancerous tissue phantoms exhibiting the lengths of mean free paths close to actual biological tissues were stacked to be bi-layered phantoms which imitates early-staged cancers. The averaged circular polarization values obtained from the images captured with the polarization camera are indicative of obvious changes depending on the thickness of cancerous layer of phantoms.