Towards true volumetric refractive index investigation in tomographic phase microscopy at the cellular level

Abstract

Tomographic phase microscopy (TPM) is one of the most widely used quantitative phase imaging techniques. It is a non-invasive, label-free technique that allows high-resolution imaging. It enables the morphology of a living cell to be captured without chemical treatment, by using the refractive index (RI) as a contrast parameter to image internal structures. In this paper, we demonstrate that due to the fact that biological cells are highly heterogeneous structures, it is crucial to use full volumetric data to calculate the average RI values of biological samples and their organelles. To prove our point, we present tomographic reconstructions of 3 cell types: neuroblastoma SH-SY5Y, adenocarcinoma A549 and leukemia HL-60, from which we calculate the average RI value from the 3D volumetric data and compare it to the average RI values calculated from each 2D section.