NSF/FDA SIR: Assessment of derating procedure using remote temperature measurements during HIFU sonication

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1137166BanerjeeHigh Intensity Focused Ultrasound (HIFU) is a minimally invasive surgical technique that has potential in interventional medicine, with applications that include tumor and fibroid ablation, vessel cauterization, and clot lyses. In the pre-clinical regulatory review of HIFU devices, characterization of devices involves multiple assessments, including prescription of the intensity field in a liquid me-dium, determination of temperature rise and lesion volume in a tissue-mimicking material or excised animal organ, and obtaining beam focus relative to the desired target. Characterization of HIFU beams is difficult at clinically relevant power levels due to the destructive potential of beams to expe-rimental sensors, as well as the possibility of interference of the sensors with the beam and the intro-duction of potential cavitation sites by these sensors. For higher intensities and powers, which are characteristics of HIFU devices, the acoustic pressure, measured in the liquid medium, can't be re-duced or ?derated? to estimate the pressure in a tissue medium. The gap in this research is that only a few HIFU devices are currently marketed in the US despite many technical advantages of HIFU. One obstacle impeding a faster path to market for HIFU devices is the lack of standardized and inex-pensive test methods for establishing the safety and efficacy of the devices. This, in turn, compli-cates the path to HIFU device commercialization, thereby limiting wider use of the devices clinically. The long-term goal of this research is to improve characterization of HIFU transducers. The ob-jective is to test a nonlinear derating method that can evaluate the thermal effects of HIFU beams. The central hypothesis is that the derated pressure, obtained from measurements in water, can deter-mine temperatures and thermal doses for assessing bioeffects in tissues.