Field concentration at any target point in interstitial hyperthermia

Studies on interstitial hyperthermia have solved the forward problem until now. Namely, the SAR curves of circular arrays of radiators, whose currents had uniform phase shifts were studied. On the other hand, SAR curves of circular arrays, whose numbers were axially shifted were also studied. In this paper the inverse problem is solved. A certain point, which may be inside or outside the array is chosen as the target point. For the target, the phases of the antenna currents are determined to maximize the total field. Also the most suitable axial shift of the radiators is also determined. It is found that, higher field concentrations can be achieved with higher operation frequencies. The maximal increase of SAR obtained is 17 dB