The effects of dynamic optical properties during interstitial laser photocoagulation.

摘要

Lasers can be used to heat and destroy cancer cells by delivering light via fiber directly into a tumour, in a novel and promising procedure called Interstitial Laser Photocoagulation (ILP). Thermal lesion formation during ILP is a dynamic process involving many heat induced alterations of tissue such as changes in optical properties and blood perfusion.; The aim of our work is to propose and validate a model which incorporates heat induced changes of optical properties due to coagulation by solving the nonlinear bioheat equation. The dynamic effects are modeled based on the Arrhenius damage formulation which describes thermal damage as an irreversible rate process. The validity of the model assumptions was investigated experimentally by developing novel opto-thermal phantoms with properties similar to those of tissue. An albumen based phantom was used to represent the case when optical properties change with heat. Polyacrylamide phantoms, designed with static optical properties, were used to illustrate the difference in temperature rise when dynamic optical properties are not taken into account. The influence of these changing optical properties on fluence, temperature and damage predictions were then examined theoretically for the case of ILP of the liver. (Abstract shortened by UMI.)