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Temperature Monitoring in Tissue Phantoms via Spatially Resolved Measurement of Longitudinal Wave Speed

Authors:
Mario Wolf
Lukas Timmermann
André Juhrig
Katharina Rath
Felix Krujatz
Elfgard Kühnicke

Keywords: Ultrasound; Temperature Monitoring; Annular Arrays; Tissue phantoms

Abstract:
To optimize hyperthermia in cancer therapy, a monitoring of temperature in the tumor and in the surrounding tissue is necessary during the therapy. As the use of Computer Tomography (CT) or Magnetic Resonance Imaging (MRI) is hardly possible during the operation, ultrasonic measurements serve as a very good alternative. This contribution introduces a method to measure the longitudinal wave speed spatially resolved by analyzing the reflected ultrasonic signals from small scatterers in a tissue phantom without needing any large reflectors at known positions. The measurements are done with pre-focused annular-arrays and the recorded signals are focused synthetically. This allows to determine the resulting signal amplitude in a fixed time window as a function of the assumed longitudinal wave speed used for focusing. The amplitude becomes maximal if the assumed sound velocity is equal to the actual one. Sliding the analysis window through the whole signal %%das Komma hier kann glaub ich weg, allows to determine the mean longitudinal wave speed for each depth. As the longitudinal wave speed depends on temperature, this gives the temperature distribution along the acoustic axis of the transducer. To qualify the technique, measurements are done on a tissue phantom for constant sound velocity. The capabilities of the method are demonstrated by monitoring the temperature distribution during local heating of a tisuue phantom. Additionally, the reachable accuracy, as well as reachable temporal and local resolution are discussed.

Pages: 98 to 102

Copyright: Copyright (c) IARIA, 2018

Publication date: September 16, 2018

Published in: conference

ISSN: 2308-3514

ISBN: 978-1-61208-660-6

Location: Venice, Italy

Dates: from September 16, 2018 to September 20, 2018