Heating patterns generated by phase modulation of a hexagonal array of interstitial antennas

An array of six interstitial microwave antennas used for hyperthermia cancer treatment is investigated. The purpose is to generate both uniform and controlled nonuniform heating patterns in biological tissue by phase modulating the signals applied to each antenna. The array consists of six antennas positioned on the corners of a hexagon. The distance between two diagonal antennas is 4 cm. The distributions of absorbed power per unit mass within the array are computed and converted into temperature distributions through a thermal conduction simulation. The specific absorption rate and temperature patterns are presented in the lateral plane (perpendicular to the antennas) and the axial plane (parallel with the antennas). By proper phase modulation of microwave signals applied to each antenna, a uniform heating pattern can be produced within the entire array volume. A peripheral heating pattern can also be generated around the array by using the proper phase modulation. The modulation schemes for generating both types of heating patterns are discussed.