Experimental Measurements and Numerical Modeling Validation of Temperature Distribution in Tissue Medium During Short Pulse Laser Irradiation

2007 ◽  
Author(s):  
Ashim Dutta ◽  
Kyunghan Kim ◽  
Kunal Mitra ◽  
Zhixiong Guo
Keyword(s):  
Numerical Modeling ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Laser Beam ◽  
Pulse Laser ◽  
Short Pulse ◽  
Hyperbolic Heat Conduction ◽  
Experimental Measurements ◽  
Conduction Model ◽  
Short Pulse Laser

The objective of this paper is to analyze the temperature distributions and heat affected zone in skin tissue medium when irradiated with either a collimated or a focused laser beam from a short pulse laser source. Single-layer and three-layer tissue phantoms containing embedded inhomogeneities are used as a model of human skin tissue having subsurface tumor. Q-switched Nd:YAG laser is used in this study. Experimental measurements of axial and radial temperature distribution in the tissue phantom are compared with the numerical modeling results. For numerical modeling, the transient radiative transport equation is first solved using discrete ordinates method for obtaining the intensity distribution and radiative heat flux inside the tissue medium. Then the temperature distribution is obtained by coupling the bio-heat transfer equation with either hyperbolic non-Fourier or parabolic Fourier heat conduction model. The hyperbolic heat conduction equation is solved using MacCormack’s scheme with error terms correction. It is observed that experimentally measured temperature distribution is in good agreement with that predicted by hyperbolic heat conduction model. The experimental measurements also demonstrate that converging laser beam focused directly at the subsurface location can produce desired high temperature at that location as compared to that produced by collimated laser beam for the same laser parameters.

A smoothing spline-based regularization of the initial inverse problem in a two-dimensional heat equation

2008 ◽  
Vol 223 (2) ◽  
pp. 439-449 ◽  
Author(s):  
K Masood ◽  
M T Mustafa
Keyword(s):  
Inverse Problem ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Smoothing Splines ◽  
Smoothing Spline ◽  
Hyperbolic Heat Conduction ◽  
Parabolic Model ◽  
Initial Profile ◽  
Conduction Model ◽  
Heat Conduction Model

A smoothing spline-based method and a hyperbolic heat conduction model is applied to regularize the recovery of the initial profile from a parabolic heat conduction model in two-dimensions. An ill-posed inverse problem involving recovery of the initial temperature distribution from measurements of the final temperature distribution is investigated. A hyperbolic heat conduction model is considered instead of a parabolic model and smoothing splines are applied to regularize the recovered initial profile. The comparison of the proposed procedure and parabolic model is presented graphically by examples.

Mathematical Models for Analyzing Tissue Ablation Using Short Pulse Lasers

2009 ◽  
Author(s):  
Ogugua Onyejekwe ◽  
Amir Yousef Sajjadi ◽  
Ugur Abdulla ◽  
Kunal Mitra ◽  
Michael Grace
Keyword(s):  
Temperature Distribution ◽  
Laser Beam ◽  
Heat Equation ◽  
Surface Temperature ◽  
Mathematical Models ◽  
Short Pulse ◽  
Ablation Depth ◽  
Tissue Ablation ◽  
Surface Temperature Distribution ◽  
Short Pulse Laser

Mathematical modeling of biological tissue ablation performed using a short pulse laser and the corresponding experimental analysis is of fundamental importance to the understanding and predicting the temperature distribution and heat affected zone for advancing surgical application of lasers. The objective of this paper is to use mathematical models to predict the thermal ablated zones during irradiation of freshly excised mouse skin tissue samples by a novel approach using a focused laser beam from a short pulse laser source. Suggested mathematical model is Stefan kind free boundary problem for the heat equation in unknown region. Temperature of the skin satisfies the classical heat equation subjected to Neumann boundary condition on the known boundary, while along the time-dependent unknown boundary, which characterizes the ablation depth, two conditions are met: (1) temperature is equal to the ablation temperature and (2) classical Stefan condition is satisfied. The latter expresses the conservation of energy at the ablation moment. A method of integral equations is used to reduce the Stefan problem to a system of two Volterra kind integral equations for temperature and ablation depth. MATLAB is used subsequently for the numerical solution. Experiments are performed using two lasers—a diode laser having a wavelength of 1552 nm and pulsewidth of 1.3 ps. The surface temperature distribution is measured using an imaging camera. After irradiation, histological studies of laser irradiated tissues are performed using frozen sectioning technique to determine the extent of thermal damage caused by the laser beam. The ablation depth and width is calculated based on the interpolated polygon technique using image processing software. The surface temperature distribution and the ablation depth obtained from the mathematical models are compared with the experimental measurements and are in very good agreement. A parametric study of various laser parameters such as time-average power, pulse repetition rate, pulse energy, and irradiation time is performed to determine the necessary ablation threshold parameters.

Analysis of dual-phase-lag heat conduction in short-pulse laser heating of metals with a hybrid method

2013 ◽  
Vol 52 (2) ◽  
pp. 275-283 ◽  
Author(s):  
Haw-Long Lee ◽  
Wen-Lih Chen ◽  
Win-Jin Chang ◽  
Eing-Jer Wei ◽  
Yu-Ching Yang
Keyword(s):  
Heat Conduction ◽  
Pulse Laser ◽  
Hybrid Method ◽  
Laser Heating ◽  
Short Pulse ◽  
Phase Lag ◽  
Dual Phase ◽  
Short Pulse Laser ◽  
Pulse Laser Heating

scholarly journals STUDY OF FOCUSING INTO CLOSELY SPACED SPOTS VIA ILLUMINATING A DIFFRACTIVE OPTICAL ELEMENT BY A SHORT-PULSE LASER BEAM

2015 ◽  
Vol 39 (2) ◽  
pp. 187-196 ◽  
Author(s):  
S. N. Khonina ◽  
S. A. Degtyarev ◽  
A. P. Porfirev ◽  
O. Yu. Moiseev ◽  
S. D. Poletaev ◽  
...  
Keyword(s):  
Laser Beam ◽  
Pulse Laser ◽  
Short Pulse ◽  
Optical Element ◽  
Diffractive Optical Element ◽  
Pulse Laser Beam ◽  
Short Pulse Laser

Experimental and Numerical Analysis of Temperature Distribution in Layered Tissue Media Due to Short Pulse Laser Irradiation

Volume 4 ◽  
2004 ◽  
Author(s):  
Ashish Trivedi ◽  
Soumyadipta Basu ◽  
Kunal Mitra ◽  
Sunil Kumar
Keyword(s):  
Pulse Laser ◽  
Lower Layer ◽  
Short Pulse ◽  
Skin Layer ◽  
Laser Source ◽  
Fatty Tissue ◽  
Measured Temperature ◽  
Conduction Model ◽  
Pulse Laser Irradiation ◽  
Short Pulse Laser

Use of short pulse laser for minimally invasive therapeutic treatment has become an indispensable tool in the technological arsenal of modern medicine and biomedical engineering. The objective of this paper is to analyze both numerically and experimentally the heat affected zone in tissue phantoms irradiated with a mode-locked short pulse laser source. It is only by being able to predict reliably the resultant temperature field that necessary dose for desired therapeutic outcomes can be ensured. A multi layer model of the skin consisting of the outer skin layer (epidermis), the lower layer (dermis) and fatty tissue underneath is considered in this study. Each layer of tissue has different optical properties. The experimentally measured temperature profiles for layered phantoms are compared with the homogenous phantoms using the non-Fourier hyperbolic and Fourier parabolic heat conduction model.

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