Deep dive into optical properties of SiliGlass tissue phantoms*

Tissue mimicking phantoms for optical applications are an important step in developing imaging systems, light-tissue models, and data analysis algorithms. The phantoms strive to provide a well-controlled set of scattering and absorption properties that are similar to those in real tissues. Majority of phantoms currently in use are either unstable or prohibitively expensive. In this contribution, we present a detailed study of a polymer-based, stable, and affordable phantom, based on the SiliGlass polymer, black pigment, and glass microspheres.

We studied the optical properties of the phantom using hyperspectral imaging in the VIS-NIR region (450 nm – 950 nm) and analyzed the microstructure of the scattering component using a scanning electron microscopy. Based on the microscopic data we evaluated the phantom scattering coefficient using Mie theory. The model of phantom scattering is used to determine concentrations of the scattering and absorption components in an inverse Monte Carlo algorithm, enabling determination of mass fractions of both absorbing and scattering phantom components. The evaluation using Mie theory also explained subtle spectral features present in the reflectance spectra of the phantoms.

Findings of this study could help in development of a well standardized optical phantom for future standardization of imaging modalities and light-tissue interaction models.