EFFECT OF PHASE MODULATION ON THE TEMPERATURE DISTRIBUTION OF A MICROWAVE HYPERTHERMIA ANTENNA-ARRAY IN-VIVO

Perfused, canine skeletal muscle and the brain tumour of a cancer pati ent were heated with an array of four parallel, interstitial antennas placed on the corners of a 2-cm square and driven at 915 MHz. The temp erature distributions along the axial and diagonal catheters were meas ured with equal-phase driving of the antennas and with several time-va rying schemes of driving phase differences among the antennas. When eq ual-phase driving was replaced by a rotating scheme of 90 degrees driv ing phase differences, the tissue area in the junction plane heated ab ove a normalized index temperature of 0.6 increased by a factor of abo ut 1.25. With a rotating phase of 135 degrees, the same area increased by a factor of about 1.6. The axial temperature distribution was not affected significantly by driving phase.