Modeling of MR-guided laser-induced interstitial thermotherapy

摘要

Abstract: The accurate prediction of the temperature and damage distribution, respectively, is a prerequisite for the successful application of the laser-induced interstitial thermotherapy of brain tumors. For the precise calculation of the resulting damage, the exact structure of the tissue in the region of interest has to be taken into account. We used the MR images of the respective brain tumor as the starting point for the computation of the light, the heat, and the consecutive damage distribution within the individual tissue structures selected for treatment. The simulation technique is based on the combination of the Monte Carlo method to calculate the light distribution and a finite difference alternative directions implicit scheme to solve the heat transfer equation. The model accounts for the specific geometry of the applicator, the changes of the optical and thermal tissue properties during the heating process, and the blood perfusion. The boundary conditions are determined by the thermal exchange between the tissue, the applicator, and the ambient medium. The predictions of the model were compared with the MR image of the resulting laser lesion induced in a patient. The relative error in the determination of the size of the damage area was found to be within 10 per cent in the direction of the applicator axis and within 20 per cent in the radial direction.!18