915 MHZ MICROWAVE INTERSTITIAL HYPERTHERMIA .2. ARRAY OF PHASE-MONITORED ANTENNAS

In order to heat the whole volume of a tumour by microwave interstitia l hyperthermia it is necessary to use an antenna array. The antenna mo delization and the numerical solution of the bidimensional bioheat tra nsfer equation allow determination of temperature evolution during a h eating session. The calculations are taken for four antennas fed in ph ase and the theory is then proven by experiments on gel and on patient s. Results are presented on cross-section heating patterns and their t ime evolution. Temperature distribution is calculated when feeding one antenna by a feeding current out of phase with the other currents. Th e phase difference value is optimized and it is then demonstrated that the heated volume is increased by successively feeding each antenna w ith an out-of-phase current. The time taken to feed each antenna one a fter the other is optimized.