Mathematical model of local heating hypodermis biological tissue by laser radiation

Abstract

Background. Laser radiation is using in medicine for the diagnosis and treatment of many diseases. It is necessary therefore to know processes that occur at the same time. They are studiing for a long time, but not all know now. The problem of interaction of laser radiation with biological targets is important. Objective. The study of thermal processes in the skin and the lower layers when heated by laser radiation, which is introduced in the fiber tissue. Materials and methods. A mathematical model of the heating region inside the process biological tissue continuous and pulsed laser radiation. The radiation is introduced into the tissue by means of optical fiber. Used heat conduction equation in spherical coordinates with internal heat sources. Taken into account the removal of heat from the heated thermal conductivity region of tissue and blood flow. Results. Regimes of heating of biological tissue by continuous laser radiation, single radiation pulses and a series of radiation pulses. It is find the sizes of the heated region, the settling time and temperature gradients. Found the dimensions of the heat regions. They are determined by the fiber diameter, the depth of radiation penetration into the tissue and the speed of heat propagation in tissue. Thermal time constant of the process time is a few minutes. After heating of the pulse radiation at the same rate the fabric cools. Conclusion. To create a need to use laser light blue or green regions of the spectrum a small local area of heating. This radiation penetrates the biological tissue a few millimeters deep. To create large areas of heating should be used near infrared region of the spectrum, where the depth of light penetration into the tissue is equal to a few tens of millimeters. Heating pulse-modulated radiation different from the heating constant output only when the pulse repetition period longer than 1 minute. Then, during the time between pulses cloth cools. Average (smoothed), the heating temperature is the same as when heating a continuous radiation.