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Source model for Immunostimulating Interstitial Laser Thermotherapy dosimetry

Emilsson, Emily LU (2017) FYSM30 20162
Department of Physics
Atomic Physics
Abstract
A common tool for tissue ablation is the use of heat. For the imILT technique investigated in this project, the heat is induced by the usage of laser light. The light is absorbed by the tissue and is thus turned into heat, the amount absorbed depends on the optical properties of the tissue, such as absorption and scattering. In imILT such as in other laser based ablation techniques, optical fibers are used to deliver the laser light to the treatment volume. The main aim of this project was to develop a source model for the imILT technique using COMSOL Multiphysics. This was done in three steps, first ray tracing inside the different fiber models, then light distribution in tissue and last heat distribution in tissue due to the introduced... (More)
A common tool for tissue ablation is the use of heat. For the imILT technique investigated in this project, the heat is induced by the usage of laser light. The light is absorbed by the tissue and is thus turned into heat, the amount absorbed depends on the optical properties of the tissue, such as absorption and scattering. In imILT such as in other laser based ablation techniques, optical fibers are used to deliver the laser light to the treatment volume. The main aim of this project was to develop a source model for the imILT technique using COMSOL Multiphysics. This was done in three steps, first ray tracing inside the different fiber models, then light distribution in tissue and last heat distribution in tissue due to the introduced laser light. A second aim of this project was to simulate the heat induced in the different fiber layers during an imILT treatment for the different fiber designs as well as comparing two fibers of the same design but of different thicknesses. The two fiber designs used were bare end and radial. The results from the developed simulation model are in large, in agreement with the validation experiments performed. The intensity profiles of the bare end fiber is approximately the same for both simulation and experiment, but differs slightly for the radial fibers. The results from the heat distribution simulation models does agree with the validation experiments but overall, the temperatures received in the simulation may be lower than for the validations. This is most likely due to the main source of error in the simulations, the optical properties of the simulated tissue. When comparing the two fibers of the same model but different thicknesses, it was concluded that different parameters limit the maximum power and treatment time that can be used for the different fiber thicknesses. (Less)
Popular Abstract (Swedish)
Den teknik som undersöks i detta projekt kallas Immunostimulating Interstitial Laser Thermotherapy (imILT), och är en teknik ämnad åt destruktion av cancertumörer. Denna teknik, så som många andra, baseras på hur värme genereras då ljus absorberas
i vävnad.

Målet med imILT-tekniken är att öka temperaturen vid tumörens kant till 46°C och bibehålla denna under en förutbestämd tid. På detta sätt dör tumören och en immunologisk respons kan därigenom aktiveras. Detta görs genom att placera en optisk fiber i mitten av tumören samt en temperaturmätare vid tumörens kant.

Detta projekt är centrerat kring utvecklingen av en simuleringsmodell för denna teknik, som beskriver både tillförseln av ljus till vävnaden och värmeutbredningen i... (More)
Den teknik som undersöks i detta projekt kallas Immunostimulating Interstitial Laser Thermotherapy (imILT), och är en teknik ämnad åt destruktion av cancertumörer. Denna teknik, så som många andra, baseras på hur värme genereras då ljus absorberas
i vävnad.

Målet med imILT-tekniken är att öka temperaturen vid tumörens kant till 46°C och bibehålla denna under en förutbestämd tid. På detta sätt dör tumören och en immunologisk respons kan därigenom aktiveras. Detta görs genom att placera en optisk fiber i mitten av tumören samt en temperaturmätare vid tumörens kant.

Detta projekt är centrerat kring utvecklingen av en simuleringsmodell för denna teknik, som beskriver både tillförseln av ljus till vävnaden och värmeutbredningen i vävnaden. Den sortens simuleringar som utvecklas under detta projekt kan användas för planering och optimering av fiberplacering inför en behandling. Simuleringar kan även minska utvecklingskostnader då antalet djurförsök och fiberprototyper kan reduceras till följd av optimering. Detta betyder att användandet av simuleringar både är kostnadseffektivt och etiskt relevant.

Modellen utvecklades med hjälp av mjukvaran COMSOL Multiphysics och validerades även experimentellt med hjälp av systemet utvecklat av Clinical Laserthermia Systems. Resultaten från simuleringarna och experimenten överensstämmer till stor del, vilket betyder att den utvecklade modellen är en bra approximation av verkligheten. Denna modell behöver dock ytterligare justeringar samt att valideras till högre grad. En av huvudfelkällorna i modellen är de optiska egenskaperna för den undersökta vävnadstypen, som för framtida projekt bör bestämmas mer exakt. Andra aspekter som bör tas hänsyn till är förändringar i de optiska egenskaperna på grund av koagulering och förkolning av vävnad. (Less)
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author
Emilsson, Emily LU
supervisor
organization
course
FYSM30 20162
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8905110
date added to LUP
2017-04-25 11:26:11
date last changed
2017-04-25 11:26:11
@misc{8905110,
  abstract     = {A common tool for tissue ablation is the use of heat. For the imILT technique investigated in this project, the heat is induced by the usage of laser light. The light is absorbed by the tissue and is thus turned into heat, the amount absorbed depends on the optical properties of the tissue, such as absorption and scattering. In imILT such as in other laser based ablation techniques, optical fibers are used to deliver the laser light to the treatment volume. The main aim of this project was to develop a source model for the imILT technique using COMSOL Multiphysics. This was done in three steps, first ray tracing inside the different fiber models, then light distribution in tissue and last heat distribution in tissue due to the introduced laser light. A second aim of this project was to simulate the heat induced in the different fiber layers during an imILT treatment for the different fiber designs as well as comparing two fibers of the same design but of different thicknesses. The two fiber designs used were bare end and radial. The results from the developed simulation model are in large, in agreement with the validation experiments performed. The intensity profiles of the bare end fiber is approximately the same for both simulation and experiment, but differs slightly for the radial fibers. The results from the heat distribution simulation models does agree with the validation experiments but overall, the temperatures received in the simulation may be lower than for the validations. This is most likely due to the main source of error in the simulations, the optical properties of the simulated tissue. When comparing the two fibers of the same model but different thicknesses, it was concluded that different parameters limit the maximum power and treatment time that can be used for the different fiber thicknesses.},
  author       = {Emilsson, Emily},
  language     = {eng},
  note         = {Student Paper},
  title        = {Source model for Immunostimulating Interstitial Laser Thermotherapy dosimetry},
  year         = {2017},
}