QUANTIFICATION OF HYPERTHERMIA PRETREATMENT PLANNING UTILITY

THIS PROJECT ADDRESSES THE DEVELOPMENT OF A QUANTITATIVE HYPERTHERMIA THERAPY PLANNING PROTOCOL. PRELIMINARY EXPERIMENTS SHOW THAT A DISTINCTIVE RELATIONSHIP EXISTS BETWEEN THE RATIO OF STEADY-STATE TEMPERATURE RISE TO SAR AND EFFECTIVE TISSUE THERMAL CONDUCTIVITY. EFFORTS WILL FOCUS ON IMPROVING MEASUREMENT INSTRUMENTATION AND METHODOLOGY FOR APPLICATION TO BOTH ULTRASOUND AND MICROWAVEHYPERTHERMIA DELIVERY SYSTEMS. THE CAPABILITIES OF THE ENHANCED THERMAL DIFFUSION PROBE WILL BE EXTENDED TO YIELD MEASUREMENTS OF TEMPERATURE, THERMAL CONDUCTIVITY, AND SAR AT MULTIPLE TISSUE SITES WITHIN A TREATMENT VOLUME THROUGH DEVELOPMENT OF MULTISENSOR AND CATHETER SENSOR PROBES. CHARACTERISTIC HEATING CURVES RELATING EFFECTIVE THERMAL CONDUCTIVITY TO LOCAL TISSUE HEATING WILL BE DEVELOPED FOR ARANGE OF HYPERTHERMIA APPLICATORS. IN THE CLINICAL SETTING,THESE CURVES, COMBINED WITH PRETREATMENT MEASUREMENTS OF EFFECTIVE THERMAL CONDUCTIVITY, CAN PREDICT THE ABILITY TO ACHIEVE THERAPEUTIC HEATING, OR WHETHER EXCESSIVE HEATING OF INTERVENING TISSUES IS LIKELY TO BE TREATMENT LIMITING. A STANDARD MEASURE OF TISSUE THERMAL CLEARANCE WILL ENABLE OBJECTIVE COMPARISON AND EVALUATION OF APPLICATORS AND MODALITIES. THE SPATIAL DISTRIBUTION OF EFFECTIVE THERMAL CONDUCTIVITY CAN BE USED AS A QUANTITATIVE BASIS FOR TAILORING THE SAR DISTRIBUTION TO THE TUMOR. CLEARLY UNTREATABLE REGIONS CAN BE IDENTIFIED TO PROVIDE THE RATIONALE FOR CANCELING OR CHANGING THERAPY.