Information on thermal history of skin tissue and iceball formation is critical for successful cutaneous cryosurgery. This paper presents a numerical analysis of tissue freezing during skin cancer treatment with liquid nitrogen (LN_2). A simplified mathematical model is constructed by including the bio-physical processes of the freezing tissues and quantifying LN_2 spray cooling with a convective heat transfer coefficient. Propagations of iceball fronts as well as lethal temperature isotherms are illustrated and quantitatively examined under various spray cooling conditions. The injury mechanisms of skin cells at different locations are also investigated based on corresponding thermal history and cooling rates during cryosurgery. These quantitative evaluations will be useful for pretreatment planning and optimization of LN_2 spray cryosurgical protocols.
展开▼
