UC San Diego
Ultrasound tomography techniques and application to thermometry
- Author(s): Nebeker, Jakob
- Nebeker, Jakob
- et al.
This work reports on the results of our work in developing Ultrasound Tomography for breast imaging and is divided into the following topics. First, we describe a new pulse- echo-based technique for creating detailed maps of sound beams and show results of the technique on a clinical ultrasound system. We map all A-Line beams and make quantitative measurements in the lateral and elevational plane, and quantify reflection and refraction caused by a cylinder of glycerin. Next, we explore our findings on ultrasound image compounding and enhancement of pulse echo data, and show 300% improvement in SNR achieved by compounding. We also show 2x resolution improvement by post-compounding spatial filtering using deconvolution and unsharp masking. Third, we detail the creation of images of local sound speed from reflection images, including extracting time of flight data and subsequent evaluation of sound speed images produced by measuring spatial resolution performance and contrast accuracy. We quantify resolution and contrast accuracy to 2.4mm and 1%. Finally, we report on a novel ultrasound thermometry method that exploits the sound speed variation of tissue with temperature to create highly-accurate temperature images. The results of this study show that ultrasound thermometry with sound speed tomography is feasible, and was accurate up to 0.29°C, for thermal monitoring in response to a local heat source, and has promise to be an excellent foundation for non-invasive, low-cost monitoring of hyperthermia in a clinical setting