The mean number of treatment sessions for the 162 PRFA treated patients was 1.80 ± 0.37. Target biopsy prior to PRFA was not performed on any of the patients because of the specific complication of tumor seeding. We confirmed that all of the PRFA treated patients achieved complete ablation (ablated zone totally enveloped the tumor without enhancement) using dynamic CT prior to patient discharge and 1 month after PRFA.