Polarization preservation in diffusive scattering from in vivo turbid biological media: effects of tissue optical absorption in the exact backscattering direction
“…13 Vitkin et al have demonstrated in vivo that light that is diffusively scattered by human skin retains significant polarization in exact backscattering directions, and the degree of polarization increases with increased absorption. 14 Sankaran et al have investigated the degree of polarization in five porcine tissues (fat, tendon, blood, myocardium muscle, and artery) of different thicknesses (0.1 to 2 mm) in transmission geometry. They have shown that the Rayleigh-scattering regime is dominant for all the tissues except blood, with the degree of linear polarization exceeding the degree of circular polarization.…”
Abstract. We present a quantitative study of depolarization in biological tissues and correlate it with measured optical properties (reduced scattering and absorption coefficients). Polarized light imaging was used to examine optically thick samples of both isotropic (liver, kidney cortex, and brain) and anisotropic (cardiac muscle, loin muscle, and tendon) pig tissues in transmission and reflection geometries. Depolarization (total, linear, and circular), as derived from polar decomposition of the measured tissue Mueller matrix, was shown to be related to the measured optical properties. We observed that depolarization increases with the transport albedo for isotropic and anisotropic tissues, independent of measurement geometry. For anisotropic tissues, depolarization was higher compared to isotropic tissues of similar transport albedo, indicating birefringence-caused depolarization effects. For tissues with large transport albedos (greater than ∼0.97), backscattering geometry was preferred over transmission due to its greater retention of light polarization; this was not the case for tissues with lower transport albedo. Preferential preservation of linearly polarized light over circularly polarized light was seen in all tissue types and all measurement geometries, implying the dominance of Rayleigh-like scattering. The tabulated polarization properties of different tissue types and their links to bulk optical properties should prove useful in future polarimetric tissue characterization and imaging studies.
“…13 Vitkin et al have demonstrated in vivo that light that is diffusively scattered by human skin retains significant polarization in exact backscattering directions, and the degree of polarization increases with increased absorption. 14 Sankaran et al have investigated the degree of polarization in five porcine tissues (fat, tendon, blood, myocardium muscle, and artery) of different thicknesses (0.1 to 2 mm) in transmission geometry. They have shown that the Rayleigh-scattering regime is dominant for all the tissues except blood, with the degree of linear polarization exceeding the degree of circular polarization.…”
Abstract. We present a quantitative study of depolarization in biological tissues and correlate it with measured optical properties (reduced scattering and absorption coefficients). Polarized light imaging was used to examine optically thick samples of both isotropic (liver, kidney cortex, and brain) and anisotropic (cardiac muscle, loin muscle, and tendon) pig tissues in transmission and reflection geometries. Depolarization (total, linear, and circular), as derived from polar decomposition of the measured tissue Mueller matrix, was shown to be related to the measured optical properties. We observed that depolarization increases with the transport albedo for isotropic and anisotropic tissues, independent of measurement geometry. For anisotropic tissues, depolarization was higher compared to isotropic tissues of similar transport albedo, indicating birefringence-caused depolarization effects. For tissues with large transport albedos (greater than ∼0.97), backscattering geometry was preferred over transmission due to its greater retention of light polarization; this was not the case for tissues with lower transport albedo. Preferential preservation of linearly polarized light over circularly polarized light was seen in all tissue types and all measurement geometries, implying the dominance of Rayleigh-like scattering. The tabulated polarization properties of different tissue types and their links to bulk optical properties should prove useful in future polarimetric tissue characterization and imaging studies.
“…Our estimations give us that the value of y varied in the range of 0.7-1.8 (except one point, where r ≈ 0.1) in the experiment of Vitkin and Studinski (10). We derived this result from their Fig.…”
Section: Relationship Between the Degree Of Polarization And The Diffmentioning
“…Traditional way to measure blood sugar level needs to prick finger to get blood, which is painful, potentially dangerous and expensive to operate. In recent ten years many non-invasive methods [3][4][5][6][7][8] have been studied to measure blood sugar level. The non-invasive methods are fast, painless, safe and convenient, but the measurement accuracy is still a barrier due to the weak signal from blood and interference of other blood components.…”
Regular monitoring of blood sugar level is important for the management of diabetes. The Near-Infra-Red (NIR) spectroscopy method is a promising approach and this involves some form of contact with the body skin. It is noted that the skin temperature does fluctuate with the environment and physiological conditions and the temperature has an influence on the glucose measurement. In this paper, in-vitro and in-vivo investigations on the temperature influence on blood glucose measurement were studied. The in-vitro results from FTIR spectrometer show that sample temperature has significant influence on water absorption, which significantly affects the glucose absorption measurement. The in-vivo results show that when skin temperature around the measurement site is taken into consideration, the prediction of blood glucose level greatly improves.
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