M. R. Bailey

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High-intensity focused ultrasound (HIFU) is a treatment modality that relies on the delivery of acoustic energy to remote tissue sites to induce thermal and/or mechanical tissue ablation. To ensure the safety and efficacy of this medical technology, standard approaches are needed for accurately characterizing the acoustic pressures generated by clinical(More)
Calibration of medical shock wave sources is critical and challenging. Aside from the fiber optic probe hydrophone, there are few if any commercially available hydrophones designed for measuring medical shock waves. We have developed a new PVDF membrane hydrophone and compared it to measurements with a fiber optic probe hydrophone (FOPH) in several(More)
It is currently difficult to assess whether a kidney stone has fractured during shock wave lithotripsy. Here we report the calculation and measurement of shock wave scattering by stone models in water. Calculations were based on linear elastic theory to find pressure in the fluid and stress in the stone models, and on scattering theory to find radiation(More)
Correct measurement of acoustic pressure is crucial in many applications, e.g. medical diagnostics and therapy, where the physical effect of ultrasound on tissue depends on specific parameters of the wave, such as positive and negative pressure, shock front thickness, and pulse duration. In our previous paper, we reported building a new low-cost PVDF(More)
Identification of stone fragmentation, or comminution, during shock wave lithotripsy (SWL) would aid a urologist in determining the treatment endpoint, but there is currently little feedback available to do so. Here we report the measurement and analysis of SW scattering by kidney stone models in water to study the inverse relationship between stone size(More)
Acoustic radiation force has many applications. One of the related technologies is the ability to noninvasively expel stones from the kidney. To optimize the procedure it is important to develop theoretical approaches that can provide rapid calculations of the radiation force depending in stone size and elastic properties, together with ultrasound beam(More)
The accurate characterization of high intensity focused ultrasound (HIFU) fields is important for the prediction of thermal and mechanical bio-effects in tissue, as well as for the development of standards for therapeutic systems. At HIFU intensity levels, the combined effects of nonlinearity and diffraction result in the formation of asymmetric shocked(More)
In this work, a new derating method to extrapolate nonlinear ultrasound fields in water to biological tissue is proposed and tested for therapeutic medical systems. Focal values of acoustic field parameters in absorptive tissue are obtained from a numerical solution to a KZK-type equation and are compared to those derated, using the proposed method, from(More)
Accurate measurement of pressure waveforms is important for characterization of medical ultrasound equipment. Calibration and measurements can be difficult for high amplitude fields such as those produced by lithotripters. Additionally, it was found previously that the response of membrane hydrophones is sensitive to water conductivity, particularly at low(More)
Transcutaneous surgical procedures performed with a high intensity focused ultrasound (HIFU) therapy system can be monitored in real-time with an ultrasound imaging system if the HIFU is gated appropriately. Without synchronization, gated or continuous HIFU saturates the imaging system and interference occludes the image. If a gating signal is synchronized(More)