Finite element analysis for simplified thermal dose planning in interstitial laser thermotherapy

Johan Olsrud; Ronnie Wirestam; Bertil R. R. Persson; Karl-Goran Tranberg

doi:10.1117/12.335801

4 January 1999 Finite element analysis for simplified thermal dose planning in interstitial laser thermotherapy

Johan Olsrud, Ronnie Wirestam, Bertil R. R. Persson, Karl-Goran Tranberg

Proceedings Volume 3565, Thermal Therapy, Laser Welding, and Tissue Interaction; (1999) https://doi.org/10.1117/12.335801
Event: BiOS Europe '98, 1998, Stockholm, Sweden

Abstract

The objective was to investigate if diffusing laser fibers can be modeled as conductive heat sources without miscalculating coagulated volumes, and if finite element analysis, disregarding light transport, may be used for 3D treatment planning in interstitial laser thermotherapy (ILT). Temperature distributions and coagulated volumes with a diffusing laser fiber, as compared to a conductive heat source, were numerically calculated at equal output power and with optical tissue properties corresponding to coagulated human liver. Blood flow was absent in the model. The maximum temperature with the diffusing fiber was limited to 100 degree(s)C and 5, 10, 20 and 30 minutes heating time was studied. A 3D finite element model was used to calculate temperatures during heating with four cylindrical heat sources (no light emission) and results were compared to measured temperatures during laser irradiation in gel with known optical properties. Coagulated volumes with a single diffusing or conductive applicator ranged from 3.5 to 12.6 cm³ and differed less than 1% at all studied irradiation times. Calculated and measured temperatures with four applicators agreed excellently. The present study should be relevant to ILT of the human liver, when inflow is occluded.

Citation Download Citation

Johan Olsrud, Ronnie Wirestam, Bertil R. R. Persson, and Karl-Goran Tranberg "Finite element analysis for simplified thermal dose planning in interstitial laser thermotherapy", Proc. SPIE 3565, Thermal Therapy, Laser Welding, and Tissue Interaction, (4 January 1999); https://doi.org/10.1117/12.335801

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