An ultrasound power supply (100) adapted for supplying electrical power for driving an ultrasound transducer (202, 702) in contact with a subject (208), wherein the ultrasound power supply comprises: - a communications interface (102) adapted for receiving a first temperature measurement of a first volume (211, 318) of the subject and a second temperature measurement of a second volume (214, 320) of the subject; - a controller (108) adapted for modulating the output of electrical power for driving the ultrasound transducer such that via ultrasonic heating by the ultrasound transducer: a. the first temperature measurement is maintained above a first predetermined threshold, b. the first temperature measurement is maintained below a second predetermined threshold, and c. the second temperature measurement is maintained below a third predetermined threshold; and wherein the first predetermined threshold is above the third predetermined threshold.