Tap water has conventionally been used as the overlay bolus circulation liquid in hyperthermia using an 8MHz radiofrequency (RF) capacitive heating device. Tap water absorbs RF thus decreasing the efficiency of deep heating. We used 0.5% NaCl as the circulation liquid to improve the efficiency of deep hyperthermia.
In phantom experiments, the deep heating efficiency increased by 1.5 °C per 5 min using 0.5% NaCl and the increase of heating efficiency was about 40%. In clinical cases, 43 °C of the intraesophageal temperature was obtained by a lower output power of 180W.
A higher deep-seated temperature can be obtained at an equal RF output using 0.5% NaCl for the overlay bolus circulation liquid.
View full abstract