Exploring 434 MHz phased array for hyperthermia heating of semi-deep targets

The problem of effective power delivery to a semi-deep tumor by a near-field phased array is addressed with reference to hyperthermia treatments. Phased array are evaluated on the basis of their ability to deliver the largest fraction of the available power from the generators to a target. With this aim, some efficiencies and an array factor are estimated for each cell of the body segment, when that cell is considered as target. The results are presented as color maps of heating efficiency and array factor. A model of tumor is the union of some of these cells. The maps may help in appreciating its heatability by the phased array. Different arrays can thus be numerically experimented to select the one which delivers most power to the tumor. Field polarization is taken into account and loss of efficiency related to polarization mismatch is considered, too. As an example, an array of 8 antennas, operating at 434 MHz, is positioned around a numerical modelling of a human head. The following figures show, for this example,: a) the Array Factor (each pixel of this image shows the Array Factor when the same pixel is the target of the optimization process); b) the polarization status for the Electric field inside the head, when one of the antennas is energized.