Cryogenic Heat Transfer Inside the Tissues with Thermally Significant Blood Vessels During Cryosurgery

To characterize the effect of thermally significant blood vessels (TSBV) on heat transfer inside the tissues during cryosurgery, the bioheat transfer equations controlling both the normal and the tumor tissues together with the Navier-Stokes equations controlling the blood flow inside the blood vessel were numerically solved. The tissues were treated as non-ideal materials with temperature dependent thermophysical properties regarding the effects of blood perfusion and metabolic heat generation in the unfrozen region. The blood was regarded as a Newton fluid with thermal dependent viscosity. It was found that the thermally significant blood vessel had much influence on the temperature distributions inside the normal and the tumor tissues, and the critical isotherm was reshaped to be widely different from that of the case without this blood vessel. Therefore, the optimization of the cryosurgery protocol when such TSBV presents becomes very important in order to avoid cure failure.