The depth of the banana and the impulse stripe illumination for diffuse optical tomography

TL;DR

This paper investigates the depth of the banana-shaped light paths in diffuse optical tomography under stripe illumination and demonstrates absorption coefficient reconstruction using time-resolved Monte Carlo simulations.

Contribution

It provides a quantitative analysis of banana depth under stripe illumination and applies time-resolved diffuse optical tomography for target absorption reconstruction.

Findings

Banana depth is approximately 0.2 times the source-detector distance.

Depth depends on optical properties and boundary conditions.

Successful absorption reconstruction via Monte Carlo simulations.

Abstract

The stripe illumination lies between the illumination in the spatial-frequency domain and the point illumination. Although the stripe illumination has a periodic structure as the illumination in the spatial-frequency domain, light from the stripe illumination can reach deep regions in biological tissue since it can be regarded as an array of point illuminations. For a pair of a source and a detector, the shape of light paths which connect the source and detector is called the banana shape. First, we investigate the depth of the banana. In the case of the zero boundary condition, we found that the depth of the center of the banana is about $0.2d_{\rm SD}$ for typical optical parameters, where $d_{\rm SD}$ is the distance between the source and detector on the boundary. In general, the depth depends on the absorption and diffusion coefficients, and the ratio of refractive indices on the boundary. Next, we perform diffuse optical tomography for the stripe illumination against forward data taken by Monte Carlo simulation. We consider an impulse illumination of the shape of a stripe. By this time-resolved measurement, the absorption coefficient of a target is reconstructed.