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MODELING THE THERMAL RESPONSE OF LASER-IRRADIATED BIOLOGICAL SAMPLES THROUGH GENERALIZED NON-FOURIER HEAT CONDUCTION MODELS: A REVIEW
Journal
Annual Review of Heat Transfer
ISSN
10490787
Date Issued
2022-01-01
Author(s)
Srivastava, Atul
Kumar, Sumit
Abstract
The ever-increasing mortality rate due to cancer has necessitated the development of new and effective techniques for selective destruction of cancerous cells. Among the various therapeutic methods, photo-thermal therapy has attracted considerable attention. The subject of photo-thermal therapy requires a detailed understanding of light-tissue interaction and the subsequent heat transfer process(es) through biological samples. The present review article focuses on the detailed review of literature on numerical modeling of the phenomena of light-tissue interaction and the resultant thermal response of laser-irradiated biological samples. While a comprehensive review of works of various researchers has been presented as a literature survey, discussion on various numerical models and the corresponding results has been primarily based on the authors’ published works. Following the principles of photo-thermal therapy, the temperature rise of biological tissue depends on the light absorption, which makes it essential to precisely model the phenomenon of laser-tissue interaction. In this context, the transient radiative transfer equation is considered to be the most accurate. Being an integrodifferential equation, complete analytical solution of the radiative transfer equation (RTE) is challenging. Hence, a range of numerical models was developed to determine the light intensity distribution within the laser-irradiated biological samples. In this direction, the transient RTE has been solved using the discrete ordinates method (DOM). The solution of the RTE has then been coupled with various bio-heat transfer models. In order to quantify the influence of convective effects on tissue temperature distribution, the pulsatile nature of blood flow in large blood vessels has been considered. The solution of the RTE has been coupled with the energy equation, and Navier-Stokes equations have been solved for the velocity field. Results of the study revealed a strong influence of the pulsatile blood flow on the temperature distribution in the surrounding tissue region. An increase in temperature due to laser-irradiation is found to be less in the presence of blood flow as compared to that achieved without blood vessels. Limitations of conventional Fourier heat conduction models in accurately predicting the temperatures of laser-irradiated biological samples have been highlighted by various researchers. These limitations arise primarily due to the assumption of the infinite speed of thermal wave propagation. Such assumptions break down in biological samples since they are primarily composed of nonhomogeneous structures. These aspects have emphasized the importance of non-Fourier heat conduction models for photo-thermal applications. With this as the motivation, the solution of the transient RTE has been coupled with the generalized form of non-Fourier heat conduction models to predict the thermal response of the tissue phantoms. The non-Fourier numerical results have also been compared to the corresponding finite integral transform (FIT)-based analytical solutions. The relative influence of relaxation times associated with the temperature gradients (τT ) and heat flux (τq) on the resultant thermal profiles has been studied and discussed. The work reported in this review article holds importance in optimizing the laser parameters for therapeutic applications so that the cell destruction is limited only up to the extent of abnormal/cancerous cells and minimum damage is incurred to the surrounding normal/healthy biological cells.
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