Monitoring of tissue optical parameters using compact sapphire probe based on diffuse reflectance analysis

Abstract

Integrating optical monitoring methods with optically based instrumentation in surgical operations may improve the efficiency of such clinical issues as intraoperative microcirculation control, cryodestruction and possible diabetes complications. Such instruments must ensure high durability, bioinertness, biocompatibility, resistance to sterilization and disinfection processes, along with high sensitivity, compact design, rapid and relatively simple quantitative determination of biological tissues’ optical parameters. To address these issues, we propose a multichanneled sapphire probe based on the principles of diffuse reflectance spectroscopy.
This probe is based on the analysis of the intensity of diffusely scattered radiation from the sample. The latter is irradiated by four emission fibers with a switching frequency of 3 Hz between channels, and the backscattered optical response is detected by an avalanche photodiode. The intensity of this signal is influenced by the tissue’s optical properties – the effective attenuation coefficient. This coefficient varies with tissue type, composition, and structure, providing diagnostic information. Thanks to its compact design, with a diameter of just 12 mm, the sapphire applicator can be used as an auxiliary instrument.
To experimentally assess the feasibility of the presented probe, liquid tissue-mimicking phantoms with varying intralipid concentration and solid two-layer phantoms with different thicknesses of the upper layer were fabricated. For liquid phantoms the probe demonstrated the measurement error less than 1% in strongly scattering media, and in tests with two-layered phantoms mimicking layered tissues, the probe exhibited sensitivity to structural variations and inclusions at depths of up to 3 mm.

Speaker

Alina Platonova
Prokhorov General Physics Institute of Russian Academy of Science
Russia

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