QUANTIFICATION OF HYPERTHERMIA PRETREATMENT PROTOCOL

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DESCRIPTION (Adapted from Applicant's Abstract): This project addresses the development of a quantitative hyperthermia therapy planning protocol. Empirical and analytical models are used to relate local temperature rise and SAR (specific absorption rate) to measurements of local tissue perfusion and thermal properties obtained prior to and during patient hyperthermia therapy. Phase I research confirmed the relation (termed the applicator "characteristic heating curve") between the local rate of thermal dissipation and the ratio of steady-state temperature rise to SAR to each point in the treatment volume. The theoretical work and the experimental results of Phase I further showed that local tissue perfusion is the critical determinant for the ratio delta T to SAR. Phase II will address the continued development of this effort, resulting in a convenient and easily applied therapy planning protocol. Tasks to be undertaken in Phase II include hardware and software development to support each of the required measured parameters (perfusion, thermal properties, temperature and SAR) at multiple tissue sites within a treatment volume. This will be followed by validation and evaluation in controlled experiments by Thermal Technologies in collaboration with our clinical collaborators. In the clinical setting, these characteristic heating curves, combined with pre-treatment measurements of tissue perfusion and thermal properties, can predict the ability to achieve therapeutic heating, or whether excessive heating of intervening tissues is likely to be treatment-limiting. This will be of immediate benefit to hyperthermia therapy: a standard measure of tissue thermal clearance will enable objective comparison and evaluation of applicators and modalities; the spatial distribution of perfusion can be used as a quantitative basis for tailoring the SAR distribution to the tumor; and clearly untreatable regions can be identified to provide the rationale for canceling therapy, for a change of applicator or modality, or for subsequent treatment with a more appropriate applicator.