Temperature Distribution In Skin Tissues Research Articles

A Study on Non-Linear DPL Model for Describing Heat Transfer in Skin Tissue during Hyperthermia Treatment.

The article studies the simulation-based mathematical modeling of bioheat transfer under the Dirichlet boundary condition. We used complex non-linear dual-phase-lag bioheat transfer (DPLBHT) for analyzing the temperature distribution in skin tissues during hyperthermia treatment of infected cells. The perfusion term, metabolic heat source, and external heat source were the three parts of the volumetric heat source that were used in the model. The non-linear DPLBHT model predicted a more accurate temperature within skin tissues. The finite element Runge–Kutta (4,5) (FERK (4,5)) method, which was based on two techniques, finite difference and Runge–Kutta (4,5), was applied for calculating the result in the case of our typical non-linear problem. The paper studies and presents the non-dimensional unit. Thermal damage of normal tissue was observed near zero during hyperthermia treatment. The effects of the non-dimensional time, non-dimensional space coordinate, location parameter, regional parameter, relaxation and thermalization time, metabolic heat source, associated metabolic heat source parameter, perfusion rate, associated perfusion heat source parameter, and external heat source coefficient on the dimensionless temperature profile were studied in detail during the hyperthermia treatment process.

Skin tissue responses to transient heating with memory-dependent derivative.

In this work, the new concept of "memory dependent derivative" in the Pennes' bio-heat transfer process of skin tissues is employed to investigate the one-dimensional problem of a skin tissue under sinusoidal heat flux conditions. Laplace transform technique is utilized to solve the problem. We investigate, numerically, the bio-heat transfer equation with memory-dependent derivative to find the effect on the tissue temperature of the kernel function and the time-delay parameter which are characteristic of memory dependent derivative heat transfer. Correlations are made with the results obtained in the case of the absence of memory-dependent derivative parameters. The effects of the time-delay on the temperature distribution in skin tissue for different forms of kernel functions are examined.

Numerical simulation of fractional non-Fourier heat conduction in skin tissue.

In this paper, a fractional non-Fourier heat conduction model is employed to simulate the heat diffusion through the skin tissue, as a biological system, upon immediate contact with a heat source. In order to study skin models and different boundary aspects, two problems: the three-layer skin tissue in contact with a hot water source and a single-layer skin tissue exposed suddenly to a heat source generated by a laser are investigated. In both cases, the super-diffusion fractional non-Fourier model is used to simulate the heat transfer diffused through the skin tissue. In the first case, the governing equation is solved using an implicit method, and in the second problem, its governing equation is solved using a finite volume method. In the fractional non-Fourier model, the effect of the model's essential parameters (αand τ) on the prediction of temperature distribution in skin tissue is studied as well as the effect of other parameters such as the blood rate is studied. In addition, grid study has been investigated and the most efficient and appropriate gird is obtained. The results are validated against the DPL (Dual-Phase Lag) model's results. The fractional single-phase-lag model's results indicate that this model is highly precise and encompasses all the results of the dual-phase-lag model. The results also show the high precision of the model, taking into account both the microstructure interactions and the lags.

Numerical simulation of time fractional dual-phase-lag model of heat transfer within skin tissue during thermal therapy

In this paper, we investigated the thermal behavior in living biological tissues using time fractional dual-phase-lag bioheat transfer (DPLBHT) model subjected to Dirichelt boundary condition in presence of metabolic and electromagnetic heat sources during thermal therapy. We solved this bioheat transfer model using finite element Legendre wavelet Galerkin method (FELWGM) with help of block pulse function in sense of Caputo fractional order derivative. We compared the obtained results from FELWGM and exact method in a specific case, and found a high accuracy. Results are interpreted in the form of standard and anomalous cases for taking different order of time fractional DPLBHT model. The time to achieve hyperthermia position is discussed in both cases as standard and time fractional order derivative. The success of thermal therapy in the treatment of metastatic cancerous cell depends on time fractional order derivative to precise prediction and control of temperature. The effect of variability of parameters such as time fractional derivative, lagging times, blood perfusion coefficient, metabolic heat source and transmitted power on dimensionless temperature distribution in skin tissue is discussed in detail. The physiological parameters has been estimated, corresponding to the value of fractional order derivative for hyperthermia treatment therapy.

METHOD OF FUNDAMENTAL SOLUTIONS FOR NONLINEAR SKIN BIOHEAT MODEL

In this paper, the method of fundamental solution (MFS) coupling with the dual reciprocity method (DRM) is developed to solve nonlinear steady state bioheat transfer problems. A two-dimensional nonlinear skin model with temperature-dependent blood perfusion rate is studied. Firstly, the original bioheat transfer governing equation with nonlinear term induced by temperature-dependent blood perfusion rate is linearized with the Taylor's expansion technique. Then, the linearized governing equation with specified boundary conditions is solved using a meshless approach, in which the DRM and the MFS are employed to obtain particular and homogeneous solutions, respectively. Several numerical examples involving linear, quadratic and exponential relations between temperature and blood perfusion rate are tested to verify the efficiency and accuracy of the proposed meshless model in solving nonlinear steady state bioheat transfer problems, and also the sensitivity of coefficients in the expression of temperature-dependent blood perfusion rate is analyzed for investigating the influence of blood perfusion rate to temperature distribution in skin tissues.

A new simplified thermoregulatory bioheat model for evaluating thermal response of the human body to transient environments

Thermal response of the human cutaneous thermoreceptors depends statically upon temperature and dynamically on the temperature change rate at the depth of the thermoreceptors. Therefore, it is very important to estimate the time-dependent thermoreceptors temperature with a good accuracy. On the other hand, the temperature distribution in skin tissue may be significantly affected by thermoregulatory mechanisms such as shivering, regulatory sweating and vasomotion. In the present study, a new simplified thermoregulatory bioheat model is proposed to describe heat transfer in skin tissue. The new model is constructed by combining the well-known Pennes equations with Gagge’s two-node model. In this model, the human skin is subdivided into three layers (epidermis, dermis and subcutaneous) and the time-dependent temperature of skin tissue is obtained by solving the bioheat equations taking into account thermoregulatory mechanisms. The model has been verified by extensive comparisons with the published analytical and experimental results where a good agreement was found. Therefore, the present model can estimate the skin temperature under transient environments with a very good accuracy.

Measurement of Blood Perfusion Using the Temperature Response to Constant Surface Flux Heating

A closed-form analytical solution of the Pennes bio-heat equation was developed for the temperature distribution in skin tissue subjected to a constant surface heat flux. Elevations in the surface temperature were revealed to be related to blood perfusion rates and heating fluxes based on which a new noninvasive approach has been developed to determine the blood perfusion rates. Sensitivities of the temperature elevation to blood perfusion and heating flux were investigated, as was the influence of thermal contact resistance on the perfusion estimate. It has been demonstrated that this influence is relatively small and can be effectively eliminated by application of highly conductive grease. An experimental system for this method was developed, and the blood perfusion rates in various human locations, including forearm, thigh, and calf, were measured using the system. The blood perfusion rate of skin tissue is in the range of 4 to 6 kg⋅s−1⋅m−3, which is in good agreement with those reported in the literature.