Two-dimensional temperature mapping for a moving agar-based tissue-mimicking phantom using diagnostic ultrasound
Description
Here the radio frequency signals (rf data) refer to the backscattered echo signals originated in a tissue-mimicking phantom. When a diagnostic ultrasound pulse propagates in a tissue medium, it is scattered by numerous scatterers. The transit time of the backscattered echoes is temperature dependent since the echoes gain a local change in the speed of sound due to any temperature change in the medium. Moreover, the thermal expansion of the propagating medium causes a physical shift in the location of the scatterers leading to a time shift of the successive rf signals. In a echo shift method a linear relationship can be established between the temperature change and the echo shift for a temperature rise up to 45 °C if non-linear effects are neglected. Thus, determining the echo shift of the successive rf signals we can measure the local temperature change in a non-invasive way for an object under thermal therapy.