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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Magnetic Resonance Imaging of Ultrasound Fields for Visualization and Measurement of Pressure Amplitudes

Passe-Carlus, Paul-Emile Victor 21 October 2024 (has links) (PDF)
In vivo pressure estimations for therapeutic ultrasound has the potential of rendering treatments using non-invasive ultrasound targeting safer and more reliable. By quantifying pressures and their respective spatial locations, better acoustic predictions and models can be made. In this thesis, we aim to measure a pressure field from a piezo-electric transducer through a ballistic gel medium by using an external gradient coil to encode the pressure field in a way that can be read and quantified using an MRI scanner. We describe the methods and the results pertaining to visualizing a pressure field. The setup was able to capture pressure field images and quantify low pressures, as compared to a hydrophone measurement, with maximum peaks of 100 kPa. We found that the confidence interval of the MRI estimated pressure to have a 95% confidence interval of 46 kPa as compared to the hydrophone measurement. We also showed that the MRI measurement setup had an accuracy of 5 kPa within 2 cm from the front of the transducer. The results showed that pressure fields could eventually be reconstructed with precision and accuracies close to that of a hydrophone equivalent acquisition. However, there are still many changes to the methodology that would need to be done.

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