Optical parameter measurement of highly diffusive tissue body phantoms with specially designed sample holder for photo diagnostic and PDT applications

Knowledge of optical properties (absorption coefficients, scattering Coefficients, and anisotropy) is necessary for understanding light tissue interactions. Optical parameters define the behavior of light in the tissues. Intralipid and Indian ink are well-established tissue body phantoms. Quantitative characterization of biological tissues in terms of optical properties is achieved with integrating sphere. However, samples having significantly higher scattering and absorption coefficients such as malignant tissues potentially reduce the signal to noise ratio (SNR) and accuracy of integrating sphere. We have measured the diffuse reflection and transmission of these phantoms by placing them in integrating sphere at 632.8 nm and then applied IAD method to determine the optical properties tissue phantoms composed of Indian ink (1.0%) and Intralipid (20%). We have fabricated a special sample holder with thin microscopic cover slips which can be used to measure signal from highly concentrated intralipid and Indian ink solutions. Experiments conducted with various phantoms reveal significant improvement of SNR for a wide range of optical properties. This approach opens up a field for potential applications in measurement of optical properties of highly diffusive biological tissues. For 20% intralipid μa =0.112±0.046 cm^-1 and μs =392.299±10.090 cm^-1 at 632.8 nm and for 1.0% Indian ink μa =9.808±0.490 cm^-1 and μs =1.258±0.063 cm^-1 at same wavelength. System shows good repeatability and reproducibility within 4.9% error. Work may have important biomedical applications in photo-diagnosis and Photodynamic therapy.