Non-Invasive Real-Time Tissue Temperature Control using Change in Backscattered Energy of RF Echo Signals during Ultrasound Hyperthermia

Real-time thermometry is vital to monitor and control tissue temperature distribution during hyperthermia treatments. Ultrasound based thermometry techniques provides good correlation with tissue temperatures to monitor thermal therapies non-invasively. In this work, the change in backscattered energy of ultrasonic radiofrequency (RF) echo signals acquired by a high frequency clinical ultrasound scanner are used to monitor tissue temperature in real-time during focused ultrasound hyperthermia. Non-invasive ultrasonic temperature estimates are used to control the power of the therapeutic transducer in real-time, controlling the thermal dose delivered to the region of interest. Controlled hyperthermia mitigates non-specific tissue damage, improving the efficacy and safety of clinical ultrasound guided focused ultrasound therapy. Furthermore, this can be used as an adjuvant modality in radiotherapy or chemotherapy for synergistic therapeutic effects. Preliminary results using ex vivo porcine muscle tissue indicate that the change in backscattered energy (CBE) driven thermometry and temperature control can be used to maintain tissue temperature at a prescribed target temperature of 40 °C to 43 °C during a hyperthermia treatment with acceptable accuracy.