FIGURE 7.

The challenge of electrode cooling. The figure shows the capacitive solution, but the situation is the same with the radiative solution, only with three-dimensional cooling (water bolus typically wraps around the patient) instead of in the two dimensions of the parallel pads. (A) The forwarded energy dose is compromised by the energy removed by cooling mechanisms. (B) The situation starts a physiological reaction which results in a positive feedback cycle: the cooling causes are reduction in blood flow to the skin, causes electrical isolation in the superficial tissues, requiring an increase in the power (voltage). This in turn increases the burn risk, so more cooling is needed, further decreasing the blood flow. And the cycle continues in a positive, non-linear loop.