Self-localization of laser induced tumor coagulation limited by heat diffusion through active tissue

Abstract

We analyze the necrosis growth due to thermal coagulation induced by laser light absorption and limited by heat diffusion into the surrounding live tissue. The tissue is assumed to contain a certain tumor in the undamaged tissue whereof the blood perfusion rate does not change during the action. By contrast, the normal tissue responds strongly to increase in the tissue temperature and the blood perfusion rate can grow by tenfold. We study in detail the necrosis formation under conditions typical for a real course of thermal therapy treatment, the duration of the action is taken about 5 minutes when a necrosis domain of size about or above 1 cm is formed. In particular, if the tumor size is sufficiently large, it exceeds 1 cm, and the tissue response is not too delayed, the delay time does not exceed 1 min, then there are conditions under which the relative volume of the damaged normal tissue is small in comparison with the tumor volume after the tumor is coagulated totally.