Calculated power absorption patterns for hyperthermia applicators consisting of electric dipole arrays.

We have applied the plane-wave spectrum method to obtain a technique for calculating the internal fields in a lossy dielectric half-space irradiated by rather arbitrary sources. We used the technique to calculate power absorption profiles of some idealized aperture sources to gain insight into how the source parameters affect the power absorption profile. With this insight, we next calculated power absorption profiles of some linear electric dipole antenna arrays. From these results we developed a simpler method of optimizing the antenna parameters by calculating their field pattern in an infinite water medium, which does not require the PWS method and is therefore faster and cheaper. Using this technique, we found an antenna array with reasonably practical parameters that produces an appealing calculated power absorption profile. We also made some calculations based on a simple approximate model that indicate that a three-element dipole array on the front of a patient and a similar one on the back could produce deep central heating. Although our calculations are based on a somewhat crude dielectric half-space model of the body, the results provide valuable insight about power absorption profiles and indicate that practical systems for producing deep internal heating without overheating the surface of the body could be developed.