Speaker
Description
Light interaction with turbid media has significant biomedical and industrial applications, including non-invasive hemodynamic monitoring and food processing. Light absorption reveals concentrations of chromophores, while scattering informs on the geometry and distribution of microstructures. Broadband continuous-wave spectroscopy (bCWS) is a simple, cost-effective approach for measuring optical attenuation over a broad spectral range. However, due to its limited dimensions of information content, disentangling the contributions of absorption and scattering from the overall attenuated signal remains a challenge. In contrast, more information-rich techniques like time-resolved spectroscopy (TRS) can reliably separate absorption and scattering; however, TRS is complex, costly, and slower than bCWS. We previously developed an algorithm based on the diffusion approximation for modelling single-distance bCWS measurements using chromophore absorption coefficients and Mie theory, which was further refined and validated in this study for estimating absolute optical properties. A series of phantom experiments was conducted, simultaneously acquiring bCWS (wavelengths: 680-920 nm) and TRS (wavelengths: 760, 808, 850, 915 nm) measurements for comparison. First, Intralipid phantoms were prepared by mixing distilled water and increasing concentrations of Intralipid, thereby increasing light scattering while absorption remained constant. Next, an Intralipid phantom was prepared with a buffer solution, and whole animal blood (Hb) and baker’s yeast (CCO) were subsequently added in two separate steps to change absorption. In the first set of phantoms, scattering increased linearly at each step, while absorption remained constant at that of pure water. In the second set of phantoms, scattering increased at each step, while absorption increased from that of pure water to the summed absorption of pure water, Hb, and CCO. The bCWS-estimated optical values demonstrated high agreement with TRS. These findings demonstrate that the algorithm reliably estimates optical properties from bCWS measurements at a single distance, providing an accessible approach for assessing optical properties of turbid media.
| Keyword-1 | Continuous-wave spectroscopy |
|---|---|
| Keyword-2 | Time-resolved spectroscopy |
| Keyword-3 | Optical properties |