Cryosurgery of a biological tissue with multiprobe: effect of central cryoprobe

In this paper a three-dimensional numerical model for cryosurgery is developed to study the effect of central probe on the cryosurgery process. The irregular boundary resulting due to the presence of cryoprobes is taken care by body-fitted multi-block non-orthogonal grids. The thermo-physical properties of biological tissue are considered as a function of temperature as phase change takes place over a wide temperature range for the biological tissue. It has been found that the cooling power requirement by the single offset cryoprobe is greater than that of the central cryoprobe. However, the presence of central cryoprobe markedly influenced the cryosurgery process, resulting in an increase in the ablation ratio by 57 % with an insignificant increase in cooling power by 4.5 %. This information can be utilised effectively in computerised planning of a cryosurgery protocol.