Bioheat Transfer Model Research Articles

Numerical simulation of the skin tissue subjected to hyperthermia treatment using a nonlinear DPL model

This article deals with the study of simulation-based mathematical modeling of tissue using the non-linear dual-phase-lag bioheat transfer (DPLBHT) model for hyperthermia treatment of tumor or cancer cells with Gaussian distribution type heat source. The metabolic heat source as an exponential variation, blood perfusion rate as a linear variation and thermal conductivity as a linear variation are considered to be temperature-dependent, resulted in a more accurate prediction of the non-linear DPLBHT model. At initial time, τq is more effective than τt in the targeted region. When the infected or cancerous cells increases in width then for effective treatment the value of the antenna constant could be decreased and the value of probe region can be changed according to the tumor location in the skin tissue. When the value of γ, Wbo, a1 and a2 increases, the temperature profile in the target region decreases. The numerical solution is obtained by hybrid scheme using Runge Kutta (4,5) and finite difference technique. This technique is compared for accuracy with an exact analytical result in a particular case as shown in figures and table and found in good compliance. The effect of lagging, metabolic heat source, blood perfusion rate, coefficient of thermal conductivity, external heat source parameter and the other associated parameter are studied in detail and the results are presented graphically.

Modeling heat transfer in humans for body heat harvesting and personal thermal management

The human thermoregulatory system dictates the transfer of heat, produced within organs and skeletal muscles, through body layers and its dissipation to the environment. With the remarkable progress in the field of heat transfer within human beings (bioheat transfer), numerical modeling of the thermal behavior of humans became possible. Such models allow a rough diagnosis of the subject’s health in various clinical conditions (humans undergoing hyperthermia or hypothermia, humans under sleep, newborn infants, etc.) and more accurate estimation of power generated from body heat harvesting devices. In this review, elements that accompany the bioheat transfer models (e.g., heat conduction through body layers, heat generation due to metabolism and blood perfusion, and heat loss mechanisms) are discussed, along with how they have been integrated to develop various numerical methods for estimating the human thermal behavior under different environmental conditions. More importantly, we introduce two representative applications of bioheat transfer models: body heat harvesting and core body temperature measuring devices. The human body is a reliable and continuous heat source that can be used for operating wearable sensors and devices. Accurately determining the amount of heat flowing into the device is crucial for estimating the power output. Furthermore, noninvasive core body temperature sensors based on bioheat transfer mechanisms are explained. Reportedly, the measurements taken with these sensors agree well with the actual core temperatures. This review will be beneficial for heat transfer engineers interested in bioheat transfer as well as for those working in the field of wearable sensors and devices pursuing a reliable energy harvester to operate their sensors.

Analytical Solution of Non Linear DPL Bioheat Transfer Model for Temperature Dependent Metabolic Heat Source During Thermal Therapy

In this research paper, the simulation based modelling of heat transfer in tissue under periodic boundary condition has been considered. The dual phase lag bioheat transfer (DPLBHT) model is implemented for computation of the temperature based thermal therapy treatment. The elements of volumetric heat source such as perfusion of blood, metabolism heat source and external heat source are considered in nonlinear DPL model. In this paper we have taken three cases for metabolic heat source namely, constant, linear and exponential. The combined two numerical methods which are based on finite difference scheme and Runge Kutta (4,5) scheme are exerted to solve the non-linear problem. We compute the exact solution for particular case. Numerical conclusions which are computed by numerical hybrid method are equated with exact result. It has been found that non linear DPL model with exponential metabolic heat source is closed to exact solution. We also expressed the effect of different parameters such as relaxation time, perfusion rate, metabolic heat source parameter, associated blood perfusion heat, heat source because of heat flux and temperature gradient etc.

A Computational Model for Nonlinear Biomechanics Problems of FGA Biological Soft Tissues

The principal objective of this work was to develop a semi-implicit hybrid boundary element method (HBEM) to describe the nonlinear fractional biomechanical interactions in functionally graded anisotropic (FGA) soft tissues. The local radial basis function collocation method (LRBFCM) and general boundary element method (GBEM) were used to solve the nonlinear fractional dual-phase-lag bioheat governing equation. The boundary element method (BEM) was then used to solve the poroelastic governing equation. To solve equations arising from boundary element discretization, an efficient partitioned semi-implicit coupling algorithm was implemented with the generalized modified shift-splitting (GMSS) preconditioners. The computational findings are presented graphically to display the influences of the graded parameter, fractional parameter, and anisotropic property on the bio-thermal stress. Different bioheat transfer models are presented to show the significant differences between the nonlinear bio-thermal stress distributions in functionally graded anisotropic biological tissues. Numerical findings verified the validity, accuracy, and efficiency of the proposed method.

Three-Phase-Lag Bio-Heat Transfer Model of Cardiac Ablation

Significant research efforts have been devoted in the past decades to accurately modelling the complex heat transfer phenomena within biological tissues. These modeling efforts and analysis have assisted in a better understanding of the intricacies of associated biological phenomena and factors that affect the treatment outcomes of hyperthermic therapeutic procedures. In this contribution, we report a three-dimensional non-Fourier bio-heat transfer model of cardiac ablation that accounts for the three-phase-lags (TPL) in the heat propagation, viz., lags due to heat flux, temperature gradient, and thermal displacement gradient. Finite element-based COMSOL Multiphysics software has been utilized to predict the temperature distributions and ablation volumes. A comparative analysis has been conducted to report the variation in the treatment outcomes of cardiac ablation considering different bio-heat transfer models. The effect of variations in the magnitude of different phase lags has been systematically investigated. The fidelity and integrity of the developed model have been evaluated by comparing the results of the developed model with the analytical results of the recent studies available in the literature. This study demonstrates the importance of considering non-Fourier lags within biological tissue for predicting more accurately the characteristics important for the efficient application of thermal therapies.

Computational modeling of poroelastic brain tumor therapy during heat transfer carrying temperature-dependent blood perfusion

In this research paper, an alternative treatment protocol based on modeling and simulation approach contrary to costly and time-consuming in vivo and in vitro studies is developed for thermal therapy of poroelastic brain tumors. Instead of constant blood perfusion, the time-dependent blood perfusion is incorporated in Penne's bio-heat transfer model to investigate its behavior both in the normal and tumor tissues. The impact of parameters of amplitude and frequency of the applied magnetic field on the heating effect is investigated. All the coupled hyperthermia processes based on finite element method-based models are simulated and analyzed quantitatively using COMSOL Multiphysics software. Temperature-dependent blood perfusion increases in healthy tissue and decreases in cancerous tissue. The infusion pressure, infusion velocity, concentration, tumor temperature, and the fraction of tumor damage are maximum at the tumor center, and these decrease in moving from the center of the tumor to the radial outward direction.

Parameter estimation in high-intensity focused ultrasound therapy.

Hyperthermia using High-Intensity Focused Ultrasound (HIFU) is an acoustic therapy for cancer treatment. This technique consists of an increase in the temperature field of the tumor to achieve coagulative necrosis and immediate cell death. Therefore, for having a successful treatment, the physical problem requires to know several properties due to the high variability from individual to individual, or even for the same individual under different physiological conditions. This article presents a numerical simulation of hyperthermia therapy for cancer treatment using HIFU, as well as the estimation of parameters that influence the physical problem. Two mathematical models were considered to solve the forward problem. The acoustic model based on acoustic pressure performs a frequency-domain study, and the bioheat transfer model a time-dependent study. These models were solved using Comsol Multiphysics® software in a 2D-axisymmetric rectangular domain to determine the temperature field. Parameter estimation was coded in Matlab Mathworks® environment using a Bayesian approach. The Markov Chain Monte Carlo method by the Metropolis-Hastings algorithm was implemented, and the simulated temperature measurements were considered. Results suggest that specific HIFU therapy can be performed for each patient by estimating appropriate parameters for cancer treatment and provides the possibility to define procedures before and during the treatment.

Numerical Modeling of Simultaneous Heat and Moisture Transport in Fire Protective Suits Under Flash Fire Exposure and Evaluation of Second-Degree Burn Time

Abstract An improved numerical model is developed for coupled heat and moisture transport in fire protective suits exposed to flash fire. This model is combined with Pennes' bioheat transfer model and subsequently, second-degree burn time is estimated using Henriques' burn integral. Natural convection is considered inside the airgap present between the multilayer clothing ensemble and the skin. Comparisons of temperature and moisture distribution within the multilayer clothing, airgap, and the skin during the exposure are presented considering combined heat and moisture transport and only heat transport. The effect of moisture transport on the protective performance of the fire protective suits is shown. The impact of both horizontal and vertical airgap orientations on second-degree burn time is studied. The effect of temperature-dependent thermophysical properties, relative humidity, fiber regain, different exposure conditions, and fabric combinations for the fire protective suits on burn time is analyzed.

Modeling and ex vivo experimental validation of liver tissue carbonization with laser ablation

ObjectiveThe purpose of this study was to model the process of liver tissue carbonization with laser ablation (LA). MethodsA dynamic heat source model was proposed and combined with the light distribution model as well as bioheat transfer model to predict the development of tissue carbonization with laser ablation (LA) using an ex vivo porcine liver tissue model. An ex vivo laser ablation experiment with porcine liver tissues using a custom-made 1064 nm bare fiber was then used to verify the simulation results at 3, 5, and 7 W laser administrations for 5 min. The spatiotemporal temperature distribution was monitored by measuring the temperature changes at three points close the fiber during LA. Both the experiment and simulation of the temperature, tissue carbonization zone, and ablation zone were then compared. ResultsFour stages were recognized in the development of liver tissue carbonization during LA. The growth of the carbonization zone along the fiber axial and radial directions were different in the four stages. The carbonization zone along the fiber axial direction (L2) grew in the four stages with a sharp increase in the initial period and a minor increase in Stage 4. However, the change in the carbonization zone along the fiber radial direction (D2) increased dramatically (Stage 1) to a long-time plateau (Stages 2 and 3) followed by a slow growth in Stage 4. An acceptable agreement between the computer simulation and ex vivo experiment in the temperature changes at the three points was found at all three testing laser administrations. A similar result was also obtained for the dimensions of coagulation zone and ablation zone between the computer simulation and ex vivo experiment (carbonization zone: 2.99± 0.10 vs. 2.78 mm2, 67.39± 0.09 vs. 63.53 mm2, and 90.53± 0.11 vs. 85.15 mm2; ablation zone: 68.95± 0.28 vs. 65.29 mm2, 182.11± 0.24 vs. 213.81 mm2, and 244.80± 0.06 vs. 251.79 mm2 at 3, 5, and 7 W, respectively). ConclusionThis study demonstrates that the proposed dynamic heat source model combined with the light distribution model as well as bioheat transfer model can predict the development of liver tissue carbonization with an acceptable accuracy. This study contributes to an improved understanding of the LA process in the treatment of liver tumors.

Generalized Bio-Heat Transfer Model Combining With the Relaxation Mechanism and Nonequilibrium Heat Transfer

Abstract The heat transport within living biological tissue is a complicated process coupled with various physiological activities. The nonhomogeneous inner anatomical structure leads to an essential difference from classical heat transfer. The generalized model of bioheat transfer involving the relaxation mechanism as well as nonequilibrium heat transfer is first proposed to explore the heat transport properties within living biological tissues. Due to the volume averaging theory, the new local instantaneous energy equations of blood and tissue are constructed separately by introducing the phase lags, in which the delay effect between the heat flux and temperature gradient absent in existing generalized models is considered. The effective phase lags covering the delay effect and nonequilibrium effect are obtained on this basis. A detailed parametric study has been conducted to estimate the values of these effective phase lags and evaluate their contributions on heat transport within living biological tissues. The results state that the effective phase lags depend on the anatomical structure of tissues and its physical properties. The delay effect is dominated in general and has a higher temperature elevation than that induced by nonequilibrium effect only.

A Coupled Bioheat Transfer Model for Customized Whole-Eye Modeling in Retinal Laser Surgery

A Coupled Bioheat Transfer Model for Customized Whole-Eye Modeling in Retinal Laser Surgery

Wavelength optimization for the laser treatment of port wine stains

Based on the well-known principle of selective photothermolysis, laser has been a promising way for the treatment of port wine stains (PWSs). The laser wavelengths used for PWS's clinical treatment include but are not limited to pulsed dye laser (PDL) in 585-600nm, long-pulse 755-nm alexandrite, and 1064-nm Nd:YAG lasers. The objective of this study was to investigate the optimal wavelength for PWS's laser treatment. A two-scale mathematic model was constructed to simultaneously quantify macroscale laser energy attenuation in two-layered bulk skin and microscale local energy absorption on target blood vessels within Krogh unit. The effects of morphological parameters, including epidermal melanin content, epidermal thickness, dermal blood content, blood vessel depth, and diameter on laser energy deposition within target blood vessels, were investigated from the visible to near-infrared bands (500-1100nm). The energy deposition ratio of target blood vessel to epidermal surface was proposed to determine the optimal laser wavelength for PWS with different skin morphological parameters. The bioheat transfer modeling and animal experiment are also conducted to prove our wavelength optimization. The optimal wavelengths for lightly pigmented skin with small and shallow target blood vessels are 580-610nm in the visible band. This wavelength coincides with commercially used PDL. The optimal wavelength shifts to 940nm as the epidermal pigmentation increases or the size and blood vessel depth increases. The optimal wavelength changes to 1005nm as the epidermal pigmentation or the size and burying depth of target blood vessel further increases. Nine hundred forty nanometers can be selected as a general wavelength in PWS treatment to meet the need in most widely morphological structure. Lasers with wavelengths in the 580-610, 940, and 1005nm regions are effective for treating PWS because of their high optical selectivity in blood over the epidermis.

Study Of Various Thermal Conductivity Layers in Bioheat Transfer Against Thermal Distribution on Human Skin with Finite Difference Method (FDM)

Development of science are often found with the connection between science and another that forms a brands newscience.one among the new sciences is biomechanics with one among its scientific fields is bioheat transfer which is applied to human skin.one among the factors that influence the heat propagation of skin tissue is thermal conductivity because theability of materials to conduct heat. the aim of this study was to work out the mathematical model of bioheat transfer with a one-dimensional finite difference method and therefore the effect of thermal conductivity on its temperature distribution. The modelis often made with combine the Pennes H.H equation to the steady state then the chosen parameter entered into it. The results of the study were compared between the finite difference method and therefore the analytic method. The results of comparative studies indicate a rise in temperature distribution but between the 2still have differences (error).Changes in environmental temperature affect the temperature distribution in human skin. While the thermal conductivity of various layers has no significant effect, the worth of temperature distributed between points increases regularly from the core of the body to the outer layer of human skin.

A numerical study on nonlinear DPL model for analyzing heat transfer in tissue during thermal therapy

AbstractIn the present paper, therapeutic treatment of infected tumorous cells has been studied through mathematical modeling and simulation of heat transfer in tissues by using a nonlinear dual‐phase lag bioheat transfer model with Dirichlet boundary condition. The components of volumetric heat source in this model such as blood perfusion and metabolism are assumed experimentally validated temperature‐dependent function, which gives more accurate temperature distribution in tissues through this model. We have used the finite difference and RK (4, 5) techniques of numerical methods to solve the proposed problem and obtained the exact solution in a particular case. After comparison, we got a good agreement between them. We have used dimensionless quantities throughout this paper. The effect of relaxation and thermalization time with respect to dimensionless temperature distribution has been analyzed in the treatment process.

A numerical study of space‐fractional three‐phase‐lag bioheat transfer model during thermal therapy

AbstractPrediction of accurate temperature profile and control of temperature are two important factors to treat the cancerous cells effectively in the living tissue during thermal therapy. To deal with this, we have generated a space‐fractional mathematical model of bioheat transfer within the living skin tissue by using three‐phase‐lag constitutive relation. The present model with Dirichlet's boundary condition is investigated in the companionship of the metabolic and external heat source during the thermal therapy. Exponentially decaying (with position) laser heat source is used as an external heating source term. To find out the solution, the model is converted to an initial value problem by using a fractional backward finite difference scheme and then Runge–Kutta (4,5) scheme is applied for determining the temperature profile within the living biological skin tissue. The effect on the dimensionless temperature profile during thermal therapy due to variations in the value of parameters like an order of space‐fractional derivative, relaxation times, blood perfusion coefficient, rate of thermal conductivity, and the external laser heat source incorporated in the current bioheat transfer model is discussed graphically. Results obtained from the study are beneficial in the field of medicine, especially for oncologists.

Fluid–Structure Interaction and Non-Fourier Effects in Coupled Electro-Thermo-Mechanical Models for Cardiac Ablation

In this study, a fully coupled electro-thermo-mechanical model of radiofrequency (RF)-assisted cardiac ablation has been developed, incorporating fluid–structure interaction, thermal relaxation time effects and porous media approach. A non-Fourier based bio-heat transfer model has been used for predicting the temperature distribution and ablation zone during the cardiac ablation. The blood has been modeled as a Newtonian fluid and the velocity fields are obtained utilizing the Navier–Stokes equations. The thermal stresses induced due to the heating of the cardiac tissue have also been accounted. Parametric studies have been conducted to investigate the effect of cardiac tissue porosity, thermal relaxation time effects, electrode insertion depths and orientations on the treatment outcomes of the cardiac ablation. The results are presented in terms of predicted temperature distributions and ablation volumes for different cases of interest utilizing a finite element based COMSOL Multiphysics software. It has been found that electrode insertion depth and orientation has a significant effect on the treatment outcomes of cardiac ablation. Further, porosity of cardiac tissue also plays an important role in the prediction of temperature distribution and ablation volume during RF-assisted cardiac ablation. Moreover, thermal relaxation times only affect the treatment outcomes for shorter treatment times of less than 30 s.

Thermoelastic behavior of skin tissue induced by laser irradiation based on the generalized dual-phase lag model.

This paper analyzes the thermoelastic responses of skin tissue during laser irradiation based on a generalized dual-phase-lag (DPL) model. The method of separation of variables is utilized to obtain the analytical solutions for thermal and mechanical responses. The influences of some crucial parameters on temperature, displacement and stress evolutions are discussed, including the phase lag of heat flux, the phase lag of temperature gradient and the phase lag of laser pulse, the coupling factor between tissue and blood, the porosity of tissue, the equivalent diameter of tissue and the diameter of blood vessels. The generalized DPL bio-heat transfer model predicts different results from those by the classical DPL model and Pennes model. The equivalent diameter of tissue affects the coupling factor between tissue and blood, while the diameter of blood vessels mainly affects the porosity of tissue.

An integral transform solution for bioheat transfer in skin tissue subjected to surface laser irradiation

Two-dimensional non-Fourier heat conduction in soft skin tissue irradiated by a laser beam on its surface is investigated on the basis of biothermomechanics. A new semianalytic solution to the thermal wave model of bioheat transfer in terms of integrals of a known function is obtained by using Laplace and Hankel transforms as well as their inverse transforms. Based on the obtained semianalytic solution, the result of numerical example indicates the thermal wave behavior caused by the non-Fourier effect is distinct. There is significant difference between the thermal wave and classical Pennes bioheat transfer.

A three-dimensional model of transient bioheat transfer in the lower extremity during cryotherapy.

The purpose of this research was to create a computational model of the human thigh undergoing cryotherapy. The tissue temperatures were measured for five cold pack temperatures of -8°C, -4°C, 0°C, 4°C, and 8°C in addition to six different time intervals of cold application and ice removal. The depth of cold penetration and duration of local tissue cooling were investigated at 10 points during 30 min of application and 7 h of post-application. The model was created in CATIA, using a mid-axial cut of the human thigh MRI without pathology. After validation by the available clinical data, this research applied the finite-volume discretization method to solve bioheat transfer equations. A 16°C decrease in the cold pack temperature reduced the tissue temperatures located 1 and 2 cm below the fat by almost 3.34°C and 1.4°C, respectively, after 30 min of cold application. It took the tissues 10-15 min to start cooling down, and the temperature reached its plateau after 100 min. Thirty minutes of cold application declined the superficial tissue and deep tissue temperatures near the bone by 22.59°C and 0.48°C, respectively. Intense cryotherapy led to an insignificant change in the deep tissue temperature at 2 cm and deeper below the fat tissue. After ice removal, tissues continued cooling down for about 8 min until 40 min, depending on the tissue depth. This study proposed a 100-min cold therapy with 10 min of ice removal to optimize tissue cooling.

Bio-heat transfer analysis based on fractional derivative and memory-dependent derivative heat conduction models

The fractional derivative (FD) and memory-dependent derivative (MDD) are efficient methods to predict the transient thermal responses. In the present paper, for the first time, the FD and MDD are introduced into classical Pennes bio-heat conduction equation with single phase-lag and the corresponding bio-heat transfer models have been formulated with the aids of thermal energy conservation equation. The Laplace transform and numerical inverse transform method are adopted to get access to thermal responses due to temperature shock. Reductions of the present models to classical Pennes and single phase-lag bio-heat transfer models are presented and comparison between different FD and MDD in transient bio-heat transfer is carried out firstly. An approximate formulation of propagation speed of thermal signal in FD models is given according to results firstly. Influences of fractional derivative parameter and tempered parameter in FD, delay time in MDD, phase-lag time and rate of blood perfusion on temperature variation and distribution are carried out numerically. Both fractional derivative and memory-dependent derivative have the ability to predict thermal response between diffusion and wave behavior and CF fractional derivative and MDD with K3 may be suitable methods.