Image of a cool tip RFA probe used in treating benign solid nodules.
RF ablation uses the heat generated from high frequency
alternating electric current oscillating between
200 and 1200 kHz . The RF waves passing through
the electrode agitate tissue ions around the electrode, and
they increase the temperature (by frictional heat) within
the tumor tissue, thus resulting in the destruction of tumor
located very close, that is, within a few millimeters, to the
electrode. In addition to the frictional heat, conduction heat
from the ablated area can result in relatively slower damage
of the tumor or to tissue remote from the electrode tip.
This process of thermal injury secondary to friction and
conduction heat is the basic mechanism of RF ablation
At temperatures between 60 and 100◦C, nearly immediate
tissue coagulation is induced with irreversible damage
caused to tumor tissue, while temperatures greater than 100–
110◦C result in tissue vaporization and carbonization which
serve as an insulator to prevent heat spread and thus reduce
the efficacy of RF ablation [11, 13]. The efficacy of RF
2 International Journal of Endocrinology
ablation can also be reduced due to (1) the heterogeneous
nature of the target tissue in the presence of fibrosis or
calcification by altering electrical and heat conduction or
(2) adjacent blood flow by perfusion-mediated tissue cooling.