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Proceedings Paper

Speed of sound estimation with active PZT element for thermal monitoring during ablation therapy: feasibility study
Author(s): Younsu Kim; Xiaoyu Guo; Alexis Cheng; Emad M. Boctor
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Paper Abstract

Controlling the thermal dose during ablation therapy is instrumental to successfully removing the tumor while preserving the surrounding healthy tissue. In the practical scenario, surgeons must be able to determine the ablation completeness in the tumor region. Various methods have been proposed to monitor it, one of which uses ultrasound since it is a common intraoperative imaging modality due to its non-invasive, cost-effective, and convenient natures. In our approach, we propose to use time of flight (ToF) information to estimate speed of sound changes. Accurate speed of sound estimation is crucial because it is directly correlated with temperature change and subsequent determination of ablation completeness. We divide the region of interest in a circular fashion with a variable radius from the ablator tip. We introduce the concept of effective speed of sound in each of the sub-regions. Our active PZT element control system facilitates this unique approach by allowing us to acquire one-way ToF information between the PZT element and each of the ultrasound elements. We performed a simulation and an experiment to verify feasibility of this method. The simulation result showed that we could compute the effective speed of sound within 0.02m/s error in our discrete model. We also perform a sensitivity analysis for this model. Most of the experimental results had less than 1% error. Simulation using a Gaussian continuous model with multiple PZT elements is also demonstrated. We simulate the effect of the element location one the optimization result.

Paper Details

Date Published: 5 May 2016
PDF: 8 pages
Proc. SPIE 9790, Medical Imaging 2016: Ultrasonic Imaging and Tomography, 97901K (5 May 2016); doi: 10.1117/12.2217086
Show Author Affiliations
Younsu Kim, Johns Hopkins Univ. (United States)
Xiaoyu Guo, Johns Hopkins Univ. (United States)
Alexis Cheng, Johns Hopkins Univ. (United States)
Emad M. Boctor, Johns Hopkins Univ. (United States)


Published in SPIE Proceedings Vol. 9790:
Medical Imaging 2016: Ultrasonic Imaging and Tomography
Neb Duric; Brecht Heyde, Editor(s)

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