Chapter 11
Simulation of the Thermal Processes
Abstract We propose the mathematical model for calculation of the hyperthymia
of a multilayer biological structure under the action of laser radiation. For the case in
vivo, the dependences of the temperature field on the refractive index and absorption
coefficient of the biological tissue under study (epidermis, the upper derma layer,
the lower derma layer, blood and its corpuscles) are determined. The obtained quantitative estimates can be used to predict the changes in the optical properties of the
biological structure that are caused by the biophysical, biochemical, and physiological processes during the action of a nonpolarized monochromatic radiation flow on
the structure surface.
11.1 Introduction
Laser therapy belongs to promising and dynamically developing fields in modern
medicine. The therapeutic action of laser radiation is related to the hypothermia of
biological tissue, which requires a model for the calculation of the temperature field
in the tissue subjected to low-intensity (noncoagulating) laser radiation. There exist
a number of works dealing with the problems of the mathematical simulation of the
laser radiation distribution in multilayer biological tissue and with the related thermal
processes. In most works [1, 2], researchers have calculated the temperature fields
appearing during the irradiation of biological tissue by a low-intensity laser beam
at various times. For example, to find the depth profile of the absorbed energy in
irradiated tissue, researchers used various numerical methods, including the discrete
coordinate method [3], finite-difference schemes [1], the Green function method [1],
and the Monte Carlo method [4]. The last method is effective for complex geometry
of a biological sample.
However, an analysis of the thermal effect of laser radiation should not be purely
physical, since it has to include biological (biophysical) studies of the response of the
© Springer International Publishing AG, part of Springer Nature 2018
K. Kulikov and T. Koshlan, Laser Interaction with Heterogeneous
Biological Tissue, Biological and Medical Physics, Biomedical Engineering,
https://doi.org/10.1007/978-3-319-94114-1_11
171
Simulation of the Thermal Processes
Abstract We propose the mathematical model for calculation of the hyperthymia
of a multilayer biological structure under the action of laser radiation. For the case in
vivo, the dependences of the temperature field on the refractive index and absorption
coefficient of the biological tissue under study (epidermis, the upper derma layer,
the lower derma layer, blood and its corpuscles) are determined. The obtained quantitative estimates can be used to predict the changes in the optical properties of the
biological structure that are caused by the biophysical, biochemical, and physiological processes during the action of a nonpolarized monochromatic radiation flow on
the structure surface.
11.1 Introduction
Laser therapy belongs to promising and dynamically developing fields in modern
medicine. The therapeutic action of laser radiation is related to the hypothermia of
biological tissue, which requires a model for the calculation of the temperature field
in the tissue subjected to low-intensity (noncoagulating) laser radiation. There exist
a number of works dealing with the problems of the mathematical simulation of the
laser radiation distribution in multilayer biological tissue and with the related thermal
processes. In most works [1, 2], researchers have calculated the temperature fields
appearing during the irradiation of biological tissue by a low-intensity laser beam
at various times. For example, to find the depth profile of the absorbed energy in
irradiated tissue, researchers used various numerical methods, including the discrete
coordinate method [3], finite-difference schemes [1], the Green function method [1],
and the Monte Carlo method [4]. The last method is effective for complex geometry
of a biological sample.
However, an analysis of the thermal effect of laser radiation should not be purely
physical, since it has to include biological (biophysical) studies of the response of the
© Springer International Publishing AG, part of Springer Nature 2018
K. Kulikov and T. Koshlan, Laser Interaction with Heterogeneous
Biological Tissue, Biological and Medical Physics, Biomedical Engineering,
https://doi.org/10.1007/978-3-319-94114-1_11
171