MICROWAVE INTERSTITIAL SENSORS AND HYPERTHERMIA PROBES

ELECTROMAGNETIC INTERSTITIAL APPLICATORS CAN BE AN EFFECTIVE WAY OF HEATING CANCER. WHEN HEATED TO 42OC TO 50OC, THE CELLS LOSE THEIR ABILITY TO DIVIDE. IN SPITE OF THE INVASIVE NATURE OF INTERSTITIAL THERAPEUTIC TREATMENT, THESE PROBES OFFER THE OPPORTUNITY TO CUSTOMIZE POWER DEPOSITION LOCALLY WITHIN TUMORS. THE FIRST AIM OF THIS RESEARCH IS TO DEMONSTRATE THE FEASIBILITY OF USING AN INDUCTIVELY COUPLED RESONANT MICROWAVE INTERSTITIAL PROBE AS A HYPERTHERMIA APPLICATOR FOR CONTROLLED DEPOSITION OF MICROWAVE POWER PATTERNS. ATTENTION WILL FOCUS ON THE MANNER IN WHICH THE PROBE IS FED TO ACHIEVE UNIFORM POWER COUPLING TO THE TISSUE ALONG THE LENGTH OF THE PROBE. TO MAXIMIZE FIELD PENETRATION INTO THE TISSUE, SPECIAL LOADING TECHNIQUES ARE USED TO MINIATURIZE THE PROBE FOR OPERATION IN THE 700 TO 900 MHZ RANGE, OR LOWER. POWER DEPOSITION PATTERS WILL BE EXPERIMENTALLY VALIDATED USING INNOVATIVE FIELD MAPPING TECHNIQUES AND LIQUIDS WHICH SIMULATE THE LOSS PROPERTIES OF TISSUE. THE SECOND OBJECTIVE IS TO DEMONSTRATE THE FEASIBILITY OF USING INTERSTITIAL SENSORS, OPERATING IN THE 3 TO 5 GHZ RANGE, FOR SENSING THE LOCAL PERMITTIVITY WITHIN THE TUMOR. BECAUSE TUMORS ARE KNOWN TO CONTAIN SIGNIFICANTLY MORE BOUND WATER THAN NORMAL TISSUE, BOTH THE REAL DIELECTRIC CONSTANT AND THE CONDUCTIVITY OF TUMORS ARE SIGNIFICANTLY LARGER. BY USING SUCH A SENSOR TO DISTINGUISH THE LOCAL REAL DIELECTRIC CONSTANT, A CATHETER CAN BE PROPERLY POSITIONED IN THE TUMOR FOR BEST TREATMENT BY AN INTERSTITIAL HYPERTHERMIA APPLICATOR.