Manufacturing of Optical Phantoms and Measurement of Their Optical Properties Using an Integrating Sphere.

Abstract

Noninvasive diagnosis by near-infrared light is widely used because it can provide physiological information about biological tissues. For quantitative measurement, however, estimation of the optical properties of biological tissues is necessary with respect to understanding of photon migration in media which scatter light strongly. The purpose of this study is to fabricate stable, solid phantoms which optically simulate biological tissues, and to measure their optical properties using an integrating sphere and a Monte Carlo simulation. The solid phantoms were fabricated using either polyester or epoxy resin as the base material, and small titanium oxide particles were mixed to provide appropriate scattering of light. Their optical properties were measured by means of spectroscopy using an integrating sphere and numerical simulation using a Monte Carlo method. The reduced scattering coefficients were measured within an uncertainty of approximately 4% and ranged from 0.3 to 1.5 mm-1, which are typical values of biological tissues in the near-infrared wavelength range. The measured absorption coefficients of the phantoms were below 0.0034 mm-1, which are satisfactorily small values.