Modeling of Laser Coagulation of Tissue With MRI Temperature Monitoring

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Xin Chen ◽  
Gerald M. Saidel
Keyword(s):  
Temperature Distribution ◽  
Magnetic Resonance ◽  
Laser Heating ◽  
Laser Energy ◽  
Magnetic Resonance Images ◽  
Laser Source ◽  
Laser Coagulation ◽  
Thermal Coagulation ◽  
Minimal Invasiveness ◽  
Coagulation Process

Light energy from a laser source that is delivered into body tissue via a fiber-optic probe with minimal invasiveness has been used to ablate solid tumors. This thermal coagulation process can be guided and monitored accurately by continuous magnetic resonance imaging (MRI) since the laser energy delivery system does not interfere with MRI. This report deals with mathematical modeling and analysis of laser coagulation of tissue. This model is intended for “real-time” analysis of magnetic resonance images obtained during the coagulation process to guide clinical treatment. A mathematical model is developed to simulate the thermal response of tissue to a laser light heating source. For fast simulation, an approximate solution of the thermal model is used to predict the dynamics of temperature distribution and tissue damage induced by a laser energy line source. The validity of these simulations is tested by comparison with MRI-based temperature data acquired from in vivo experiments in rabbits. The model-simulated temperature distribution and predicted lesion dynamics correspond closely with MRI-based data. These results demonstrate the potential for using this combination of fast modeling and MRI technologies during laser heating of tissue for online prediction of tumor lesion size during laser heating.

Thermal Stress Associated With Non-Fourier Heat Conduction in Femtosecond Laser Heating of Multilayer Metallic Films

2018 ◽  
Author(s):  
Swarup Bag ◽  
M. Ruhul Amin
Keyword(s):  
Thin Film ◽  
Heat Conduction ◽  
Thermal Stress ◽  
Temperature Distribution ◽  
Pulse Laser ◽  
Laser Heating ◽  
Laser Source ◽  
Phase Lag ◽  
Dual Phase ◽  
Fourier Heat Conduction

In the present work, the deformation behavior in metallic film subjected to ultra-short laser heating is investigated. Static thermo-elastic behavior is predicted for 100 nm thin film of either single layer or multiple layers. The temperature distribution is estimated from dual-phase lag non-Fourier heat conduction model. The maximum temperature after single pulse is achieved 730 K. The temperature profile for this pulse laser is used to compute elastic stress and distortion field following the minimization of potential energy of the system. In the present work, the simulation has been proposed by developing 3D finite element based coupled thermo-elastic model using dual phase lag effect. The experimental basis of transient temperature distribution in ultra-short pulse laser is extremely difficult or nearly impossible, the model results have been validated with literature reported thermal results. Since the temperature distribution due to pulse laser source varies with time, the stress analysis is performed in incremental mode. Hence, a sequentially coupled thermo-mechanical model is developed that is synchronized between thermal and mechanical analysis in each time steps of transient problem. The maximum equivalent stress is achieved 0.3 GPa. Numerical results show that the predicted thermal stress may exceeds the tensile strength of the material and may lead to crack or damage the thin film.

scholarly journals Investigation of Laser-material Interaction in Case of Aluminium Brazing Process

2018 ◽  
Author(s):  
Tamás Markovits ◽  
András Jászberényi
Keyword(s):  
Co2 Laser ◽  
Laser Heating ◽  
Laser Energy ◽  
Research Work ◽  
Base Material ◽  
Laser Source ◽  
Laser Material ◽  
Heating Source ◽  
Laser Absorption ◽  
Material Interaction

This research work is connected to the applicability of laser source in case of brazing of aluminium materials. Based on our earlier research results it become clear that the brazing flux material is able to improve the laser absorption in case CO2 laser source. A new brazing flux material (Fontargen F 400 MD EVO2) and the CO2 laser interactions were investigated to determine the applicability of laser as a heating source. The application of laser strongly depend on the value of absorption of laser energy into the aluminium base material. From our new result it can be seen that the applied flux can improve the laser absorption, thus the laser heating, but the implementation of brazing process with this flux material brings further challenges.

An emerging technology: Nuclear magnetic resonance microscopy

1988 ◽  
Vol 46 ◽  
pp. 1000-1001
Author(s):  
M.J. Hennessy ◽  
E. Kwok
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Basic Research ◽  
Local Environment ◽  
Magnetic Resonance Images ◽  
Nmr Microscopy ◽  
Mri Scans ◽  
Temperature Relaxation ◽  
Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

Functional information from magnetic resonance imaging

1995 ◽  
Vol 53 ◽  
pp. 84-85
Author(s):  
Alan P. Koretsky ◽  
Afonso Costa e Silva ◽  
Yi-Jen Lin
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Cancer Biology ◽  
Imaging Modality ◽  
Magnetic Resonance Images ◽  
Great Success ◽  
Functional Information ◽  
Resonance Imaging ◽  
High Resolution Mri

Magnetic resonance imaging (MRI) has become established as an important imaging modality for the clinical management of disease. This is primarily due to the great tissue contrast inherent in magnetic resonance images of normal and diseased organs. Due to the wide availability of high field magnets and the ability to generate large and rapidly switched magnetic field gradients there is growing interest in applying high resolution MRI to obtain microscopic information. This symposium on MRI microscopy highlights new developments that are leading to increased resolution. The application of high resolution MRI to significant problems in developmental biology and cancer biology will illustrate the potential of these techniques.In combination with a growing interest in obtaining high resolution MRI there is also a growing interest in obtaining functional information from MRI. The great success of MRI in clinical applications is due to the inherent contrast obtained from different tissues leading to anatomical information.

Anatomical Description of an Infant Bottlenose Dolphin (Tursiops truncatus) Brain from Magnetic Resonance Images

2004 ◽  
Vol 30 (2) ◽  
pp. 315-326 ◽  
Author(s):  
Lori Marino ◽  
Keith Sudheimer ◽  
D. Ann Pabst ◽  
William A. Mclellan ◽  
Saima Arshad ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
Magnetic Resonance Images
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