Speed of sound estimation with active PZT element for thermal monitoring during ablation therapy: Feasibility study

Younsu Kim, Xiaoyu Guo, Alexis Cheng, Emad M. Boctor

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


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.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2016
Subtitle of host publicationUltrasonic Imaging and Tomography
EditorsBrecht Heyde, Brecht Heyde, Neb Duric
ISBN (Electronic)9781510600256
StatePublished - 2016
EventMedical Imaging 2016: Ultrasonic Imaging and Tomography - San Diego, United States
Duration: Feb 28 2016Feb 29 2016

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherMedical Imaging 2016: Ultrasonic Imaging and Tomography
Country/TerritoryUnited States
CitySan Diego


  • Speed of sound estimation
  • optimization
  • thermal monitoring
  • ultrasound guidance

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging
  • Biomaterials


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