Estimation of temperature distribution in biological tissue by using solutions of bioheat transfer equation

2008 ◽  
Vol 37 (6) ◽  
pp. 374-386 ◽  
Author(s):  
Shigenao Maruyama ◽  
Junnosuke Okajima ◽  
Atsuki Komiya ◽  
Hiroki Takeda
Keyword(s):  
Temperature Distribution ◽  
Biological Tissue ◽  
Transfer Equation ◽  
Bioheat Transfer ◽  
Bioheat Transfer Equation

Experimental and Numerical Evaluation of Small-Scale Cryosurgery Using Ultrafine Cryoprobe

2013 ◽  
Author(s):  
Junnosuke Okajima ◽  
Atsuki Komiya ◽  
Shigenao Maruyama
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Biological Tissue ◽  
Bioheat Transfer ◽  
Small Scale ◽  
Outer Diameter ◽  
Two Phase ◽  
Inner Diameter ◽  
Surgical Treatments ◽  
Tube Structure

Cryosurgery is one of the surgical treatments using a frozen phenomenon in biological tissue. In order to reduce the invasiveness of cryosurgery, the miniaturization of cryoprobe, which is a cooling device for cryosurgery, has been required. The authors have developed a ultrafine cryoprobe for realizing low-invasive cryosurgery by the local freezing. The objective of this study is to evaluate the small-scale cryosurgery using the ultrafine cryoprobe experimentally and numerically. The ultrafine cryoprobe has a double-tube structure and consists of two stainless microtube. The outer diameter of ultrafine cryoprobe was 550 μm. The inner tube, which has 70 μm in inner diameter, depressurizes the high-pressure liquidized refrigerant. Depressurized refrigerant changes its state to two-phase and passes through the gap between outer and inner tube. The alternative Freon of HFC-23 was used as a refrigerant, which has the boiling point of −82°C at 0.1 MPa. The cooling performance of this ultrafine cryoprobe was tested by the freezing experiment of the gelated water kept at 37°C. The gelated water at 37°C is a substitute of the biological tissue. As a result of the cooling in 1 minute, the surface temperature of the ultrafine cryoprobe was reached at −35°C and the radius of frozen region was 2 mm. In order to evaluate the temperature distribution in the frozen region, the numerical simulation was conducted. The two-dimensional axisymmetric bioheat transfer equation with phase change was solved. By using the result from the numerical simulation, the temperature distribution in the frozen region and expected necrosis area is discussed.

Theoretical Analysis of Transient Bioheat Transfer in Multi-Layer Tissue

2015 ◽  
Author(s):  
Daipayan Sarkar ◽  
A. Haji-Sheikh ◽  
Ankur Jain
Keyword(s):  
Transfer Equation ◽  
Physical Phenomenon ◽  
Separation Of Variables ◽  
Blood Perfusion ◽  
Bioheat Transfer ◽  
Skin Tissue ◽  
Transient Temperature ◽  
Theoretical Understanding ◽  
Transient Model ◽  
Bioheat Transfer Equation

Heat conduction in skin tissue is a problem of significant technological importance. A theoretical understanding of such a problem is essential as it may lead to design potential therapeutic measures for needed cancer therapy or novel medical devices for various applications including hyperthermia. To understand the physical phenomenon of energy transport in biological systems a transient model is chosen for this study. The most common transport equation to estimate temperature distribution in humans was developed by H.H. Pennes and is popularly known as the Pennes bioheat transfer equation. A generalized Pennes bioheat transfer equation accounts for the effect of various physical phenomena such as conduction, advection, volumetric heat generation, etc. are considered. In this paper, a general transient form of the Pennes bioheat transfer equation is solved analytically for a multilayer domain. The boundary value problem considers the core of the tissue is maintained at uniform temperature of 37°C, convective cooling is applied to the external surface of the skin and the sidewalls are adiabatic. The computation of transient temperature in multidimensional and multilayer bodies offers unique features. Due to the presence of blood perfusion in the tissue, the reaction term in the Pennes governing equation is modeled similar to a fin term. The eigenvalues may become imaginary, producing eigenfunctions with imaginary arguments. In addition the spacing between the eigenvalues between zero and maximum value varies for different cases; therefore the values need to be determined with precision using second order Newton’s method. A detailed derivation of the temperature solution using the technique of separation of variables is presented in this study. In addition a proof of orthogonality theorem for eigenfunctions with imaginary eigenvalues is also presented. The analytical model is used to study the thermal response of skin tissue to different parameters with the aid of some numerical examples. Results shown in this paper are expected to facilitate a better understand of bioheat transfer in layered tissue such as skin.

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