[Estimation of the extent of malignant tumor damage in laser interstitial thermal therapy].

A one-dimensional mathematical model has been developed for the thermal malignant tumor damage caused by Nd:YAG laser infrared radiation through a light guide. The model is based on the transient thermal conduction equation and considers the effects of intratissue blood flow, tissue radiation absorption, phase transition (evaporation) and varying tissue thermal tolerance. Examples of computer-aided numerical calculations are presented. A relation of the sizes of the specific areas of thermal tumor tissue damage to the magnitude of radiation, treatment time, blood flow rates, and tissue thermal tolerance is shown. The calculation results are compared with the experimental data obtained on laboratory animals. The calculation model and programme are proposed to be clinically used while planning laser interstitial thermal therapy for human malignant tumors.