A 2D transmission line matrix model is used to study thermal transfer in living tissues exposed to laser energy. Damage size because of thermal coagulation in thermal treatment of benign prostate hyperplasia is determined quantitatively. Results show a quasilinear dependency of blood perfusion on temperature at the beginning of coagulation. Immediately thereafter, blood perfusion decreases considerably until it shuts down when the tissue under investigation has been coagulated. Increase in perfusion rate (ω) leads to high values of t 100 , which is the time required to reach a primary zone temperature of about 100°C, and reflects the increased cooling created by perfusion. The transmission line matrix numerical model predicts the coagulation damage contours; that way, it has a clinical interest in therapy as an aid for clinicians because damage cannot be easily measured within patients. Results are validated through comparison with other researches.

The transmission line matrix (TLM) method is developed to efficiently solve the bioheat transfer with phase change in freeze-thaw cryoablation. This new design of three dimensional TLM model with an automatic time stepping is based on hyperbolic heat transfer model. It is able to consider many factors such as temperature-dependant thermophysical properties during phase change, blood perfusion and latent heat release/absorption. Thermal analysis of heat transfer in the cryotreated tissue is detailed; with special emphases on lethal temperature isotherms with respect to the cooling rates and duration of freeze-thaw cycle. The basic numerical model is validated through available experimental data on skeletal muscle of rabbit hind-limbs. Nomenclature c Volumetric specific heat (J/m 3 °. C) L Latent heat l Liquid phase ls Liquid-solid phase m Metabolic heat p Perfusion s Solid phase RECEIVED