Field focusing and focal heating patterns using a hybrid radiofrequency hyperthermia system

A novel three-element radiofrequency hyperthermia system, consisting of paired multiple-feed inductors positioned between two large capacitor plates and a moveable grounding point, was designed and constructed. The spatial orientation of these elements and the phase of the current flowing through them can be varied to produce asymmetric magnetic field patterns resulting in development of asymmetric eddy current patterns orthogonal to the magnetic lines of force. These patterns could be further focused by manipulation of the capacitor plates and grounding point. Field and eddy current patterns were subsequently correlated with two-dimensional heating patterns at midplane depth in solid phantoms.