Computer simulations on multiprobe freezing of irregularly shaped tumors

Cryosurgery is particularly suitable for the treatment of unresectable liver tumors. However, a major bottleneck is encountered during the treatment of large-sized irregularly shaped tumors. Large and complex liver tumors have varying degree of shape irregularity. Adopting a multiprobe freezing model, simulations for an irregularly shaped liver tumor were conducted. The model, validated with both in-vitro data from an experimental setup, showed good agreement of up to 5.8%. The chosen mathematical treatment and simulation technique permit the study of employing multiple cryoprobes to destroy cancer cells in irregularly shaped tumors. Results from our study indicated that multiple cryoprobes can be strategically positioned to form ice-fronts with various contours that adhere to the shape and size of the tumor. The amount of cell-deaths within the tumor after the -50°C ice-front can be quantitatively calculated to determine the efficacy of different multiprobe arrangements in order to maximize cell destruction. The paper also underlines a piecewise approach of using several cryoprobes to quickly 'sculpt' the desired shape of the ice-front based on the physical morphology of an irregular-shaped tumor. This numerical study forms an essential framework in allowing surgeons to make informed decisions on the most effective surgical protocol based on the degree of irregularity in shape and size of tumor.