*1.3.1. Radiofrequency ablation*

The different manufacturers employed various strategies to obtain larger ablation zones [7]; there are currently three different manufacturers that offer commercial radiofrequency tumor ablation devices in the USA (Boston Scientific, Rita Medical and Valleylab) and an additional one in Europe (Celon). Two manufacturers (Boston Scientific and Rita Medical) employ multitined electrodes, to increase electrode surface area and volume of tissue heating. For multitined electrodes typically an incremental deployment of the tines in stages is used, with ablation at each deployment stage for a certain amount of time or until the target temperature is achieved to ensure complete ablation of the target volume. Two manufacturers use internal electrode cooling via circulation of water or saline to increase ablation zone size (Valleylab and Celon). By cooling the electrode, the tissue surrounding the electrode is also cooled. The location of maximum temperature is 'pushed' further into the tissue, resulting in a larger ablation zone size. A similar effect is obtained by infusing saline into the tissue via ports in the electrode this method is used by the Starburst Xli™ electrode [8].
