In the field of ultrasound therapy, the estimation of temperature to monitor treatments is becoming essential. We hypothesize that it is possible to measure temperature directly using a constant acoustic power burst. Under the assumption that the acoustic attenuation does not change significantly with temperature, the thermal strain induced by such bursts presents a linear relation with temperature. A mathematical demonstration is given in the introduction. Then, simulations of ultrasound waves in a canine liver model were conducted at different temperatures (from 20 °C to 90 °C). Finally, experimental measurements on phantom samples were performed over the same temperature range. The simulation and experimental results both showed a linear relation between thermal strain and temperature. This relation may suggest the foundation of a new ultrasound-based thermometry method. The potential and limitations of the method are discussed.

The objective of this study is to present a new thermometry method, based on thermal strain imaging, to estimate the absolute temperature using ultrasound. Unlike the conventional method presented in previous studies, this method does not require knowledge of the initial temperature or of speed of sound. The method was tested in simulations and experimentally. Simulations were performed at different temperatures (from 20 to 90 °C), using k-wave. Then, experimental measurements were performed in Zerdine phantom samples at different temperature (from 23 to 88 °C). A linear array transducer, with a 12-angle plane wave imaging sequence, was used to acquire the thermal strain images and to derive the temperature at the focus. To control the temperature during the measurements, a thermocouple was used. Both simulations and experiments showed a good estimation of the temperatures. The new ultrasound-based method is a promising technique to estimate and monitor temperature during thermal ablation.