Three-dimensional biological tissue under high-order effect of two-temperature thermal lagging to thermal responses due to a laser irradiation

Using the lasers and heat transfer through biological skin tissue is essential for the processes of the medical treatment. Thus, two-temperature bio-heat transfer equations were introduced and used to discuss the variation of temperature in a laser-irradiated biological tissue. As a result, the Laplace and Fourier transform techniques have been applied, and the solutions of the conductive temperature have been represented in figures. The two-temperature parameter, the penetration depth parameter, the dimensions of the rectangular laser pulse, and the power density of laser irradiation parameter have significant effects on the thermal waves through the skin tissue.


Introduction
In the medical applications, the use of lasers has increased over the past half-century.For increasing the therapy quality, the observation of thermal damage is important.Effect of the laser irradiation on the biological tissues takes different types.The most common of those applications include the thermal effects.The thermal interaction is the most important since temperature rising due to thermal effects is a final factor to produce thermal damage.Due to lack of knowledge about the thermal reaction and response, the clinical doctors could not control the times of using the laser power [1][2][3][4].To predict the thermal damage quantity, it is required to study the thermal response caused by the laser energy deposition.As a result, the analysis of thermal transport is essential to make an improvement to the treatment qualification and for more safety.The experiment is an essential method to know the medical treatment problems [4,5].The most famous researchers studied the bioheat transfer in the biological skin tissues are Pennes [6], Abramson [7].The Pennes bio-heat transfer equation is used to simulate and model the thermal behavior in the biological bodies.The review paper [8] represented many attempts to model the thermal behavior of the human body.Xu et al. [9,10] presented a system discussion to the DPL effects on the bio-thermo-mechanical behavior of skin tissues.The linear DPL equation has been used in various theoretical studies [11][12][13].Youssef applies the two-temperature heat conduction in many applications [14,15].

Materials and method
Consider homogeneous skin tissue in three-dimensional fills the region Ψwhich is defined by Ψ = , , : 0 ≤  ∞, −∞  ∞, −∞  ∞ where the skin is initially at rest and has been thermally shocked by laser irradiation with a rectangular pulse at the bounding plane to the surface.Tzou proposed the DPL model in the classical heat flux model as [16].Youssef proposed the two-temperature model to differentiate between the conductive temperature and the dynamical temperature as [17].
where  is the temperature,  the heat conductivity,  is the time,  ,  are the phase lag of the heat flux and the phase lag of the temperature gradient, respectively,  is the density,  is the specific heat,  and  are the specific heat and perfusion rate of blood. is the metabolic heat generation and  is the heat source for spatial heating,  is the arterial temperature,  is the conductive temperature, and  is the dynamical temperature: where  is a non-negative parameter which is called two-temperature parameter.
The term    −  expresses the heat caused by convection within the head per unit mass of the tissue and it is considered to be homogenous.
Due to the chemical reactions within the tissues, the metabolic heat source is valid, and it is assumed to be a constant  = 368.1 W/m 3 .When the laser beam shocked the skin surface, the laser energy is absorbed, scattered, and transmitted.Lambert expresses the laser power intensity along the tissue depth-Beer's law, as follows [2]: Heat generation due to scattering is assumed to be negligible; therefore, the specific absorption rate in the target zone can be expressed as follows: In the Eq. ( 6),  (W/m 2 ) represents the power density of laser irradiation and   is the Heaviside unit step function.The parameter  represents the penetration depth.It means, the rectangular thermal pulse of the laser irradiation acts on a band of width 2 centered on the -axis and 2 centered around the -axis on the surface of the half-space  = 0 and is zero elsewhere: Applying the Laplace transform for Eqs. ( 5), ( 7) and ( 8) defined as: where: Thus, we get: where ℎ = 1 +  − , ℎ = 1 +  − .

The governing equations in the Fourier transform domain
Using double Fourier transform for any function  ,  which is defined as follows: ̅ , , ,  =  ̅ , , ,  = 1 2  ̅ , , ,    , where the inversion transform of the double Fourier transform takes the form: Hence, we have: By eliminating  ̅ from Eqs. ( 15) and ( 16), we get the following differential equation: where: 1 1 5 The general solution of the differential Eq. ( 17) takes the form: where  and  are some parameters which have to be determined.Apply the boundary conditions: Hence, we obtain: where:

Results
The values of the relevant thermal parameters used in the present calculations are as follows in Table 1 [4,9,13,18].

Discussion
Fig. 1 shows the conductive temperature increment with a range of  -axis and various positions of  and .The values of both  and  have significant effects.When the values of  and  are increasing, the value of the conductive temperature increment is decreasing.Fig. 2 shows the conductive temperature increment with a range of -axis and various value of  and  =  = 0.0.The value of  has a significant effect.When the value of  is increasing, the value of the conductive temperature is increasing.Fig. 3 shows the conductive temperature distribution with a range of -axis and various value of  when  =  = 0.0.The value of  has a significant effect.When  is decreasing, the value of the conductive temperature is decreasing.Fig. 4 shows the conductive temperature distribution with a range of -axis and various ,  and  =  = 0.0.The values of  and  have significant effects.When the values of  and  are increasing, the VIBROENGINEERING PROCEDIA.MARCH 2019, VOLUME 22 value of the conductive temperature is increasing.Fig. 5 shows the conductive temperature distribution with a range of -axis and various value of  when  =  = 0.0.The value of  has a significant effect.When the value of  is increasing, the value of the conductive temperature is increasing.

Conclusions
The two-temperature parameter, the dimensions of the rectangular laser pulse, the penetration depth parameter, and the power density of laser irradiation have significant effects on the conductive temperature.

Table 1 .
The material properties of the skin tissue