5.13 Analysis of Spectral Characteristics of Radiation Scattered by …
457
skin [272, 273] amounts to approximately 4–7% of the power of incident radiation.
Consequently, in the inner skin layers, approximately 93–96% of the incident on its
radiation is absorbed and scattered. The diffuse component of scattered radiation is
a function of the processes of absorbing and scattering from the inner skin layers,
which are reached by the incident radiation.
The results of the measurements of the radiation reflected from the skin on certain
selected wavelengths can be used for the quantitative estimation of the changes of
pigments of skin. As the penetration depth of optical radiation into the tissue depends
on the wavelength of the incident radiation, the allocation of pigments in various skin
layers influences the spectral composition of the radiation, which reaches this layer.
Absorbing regions corresponding to each of the main dermal chromophores can
be determined as minima of spectral reflection in vivo [274–276]. The possibilities of
this method include the determination of vasodilation conditions, oxygen saturation
of skin blood flow, levels of bilirubin and melanin pigmentation.
The measurements of bilirubin levels, skin chromophores, hemoglobin and oxyhemoglobin in skin blood flow have great importance for the diagnostics of the peripheral vascular diseases and, vasomotor disorders [270–273]. The studies of the absorption areas of oxyhemoglobin and hemoglobin at the registration of spectra of radiation
scattered by skin allow estimating the concentration of given chromophores in skin
blood flow.
5.13.1 Measurement of Spectral Reflection Coefficients
of Human Skin
The experimental studies of spectral reflection coefficient of skin preparation
(epidermis and dermis) in vitro and skin in vivo showed considerable differences
in curves of the reflection coefficient. In particular, for the skin in vivo the presence
of typical absorption peaks at wavelengths of 542.577 nm is registered [277, 278].
We have carried out the studies of spectral reflection coefficient of skin in vivo
on the inner side of a thumb of 8 people (4 men and 4 women) at the age from 20
to 40. For more precise measurements of the reflection coefficient, the spectrophotometer “Specord M-40” with the attachment for the measurement of reflection with
photometric sphere was used, as the reflection of skin is diffusive. Beforehand, the
reproducibility of the results of measurements was studied. Repeatedly spectral ratio
of reflection coefficients K and mean-square deviation σ for various spectral intervals
(Table 5.1) were recorded.
In the works of foreign researchers [279], it was stated that the tendency of
measurement of curves of reflection coefficients of skin of fingers in vivo of men
and women is the same; however, the curves of reflection coefficient of women have
bigger amplitude than the corresponding curves of men.
With the aim of conducting the comparative analysis of spectral curves (Fig. 5.59)
at wavelengths of 400, 450, 500, 560, 600, 650, 750 nm, the calculations of average
457
skin [272, 273] amounts to approximately 4–7% of the power of incident radiation.
Consequently, in the inner skin layers, approximately 93–96% of the incident on its
radiation is absorbed and scattered. The diffuse component of scattered radiation is
a function of the processes of absorbing and scattering from the inner skin layers,
which are reached by the incident radiation.
The results of the measurements of the radiation reflected from the skin on certain
selected wavelengths can be used for the quantitative estimation of the changes of
pigments of skin. As the penetration depth of optical radiation into the tissue depends
on the wavelength of the incident radiation, the allocation of pigments in various skin
layers influences the spectral composition of the radiation, which reaches this layer.
Absorbing regions corresponding to each of the main dermal chromophores can
be determined as minima of spectral reflection in vivo [274–276]. The possibilities of
this method include the determination of vasodilation conditions, oxygen saturation
of skin blood flow, levels of bilirubin and melanin pigmentation.
The measurements of bilirubin levels, skin chromophores, hemoglobin and oxyhemoglobin in skin blood flow have great importance for the diagnostics of the peripheral vascular diseases and, vasomotor disorders [270–273]. The studies of the absorption areas of oxyhemoglobin and hemoglobin at the registration of spectra of radiation
scattered by skin allow estimating the concentration of given chromophores in skin
blood flow.
5.13.1 Measurement of Spectral Reflection Coefficients
of Human Skin
The experimental studies of spectral reflection coefficient of skin preparation
(epidermis and dermis) in vitro and skin in vivo showed considerable differences
in curves of the reflection coefficient. In particular, for the skin in vivo the presence
of typical absorption peaks at wavelengths of 542.577 nm is registered [277, 278].
We have carried out the studies of spectral reflection coefficient of skin in vivo
on the inner side of a thumb of 8 people (4 men and 4 women) at the age from 20
to 40. For more precise measurements of the reflection coefficient, the spectrophotometer “Specord M-40” with the attachment for the measurement of reflection with
photometric sphere was used, as the reflection of skin is diffusive. Beforehand, the
reproducibility of the results of measurements was studied. Repeatedly spectral ratio
of reflection coefficients K and mean-square deviation σ for various spectral intervals
(Table 5.1) were recorded.
In the works of foreign researchers [279], it was stated that the tendency of
measurement of curves of reflection coefficients of skin of fingers in vivo of men
and women is the same; however, the curves of reflection coefficient of women have
bigger amplitude than the corresponding curves of men.
With the aim of conducting the comparative analysis of spectral curves (Fig. 5.59)
at wavelengths of 400, 450, 500, 560, 600, 650, 750 nm, the calculations of average