Various approaches to generating and maintaining an ultrasound focus at a target region include configuring a controller to cause transmission of treatment ultrasound pulses from a transducer having multiple transducer elements; cause the transducer to transmit focusing ultrasound pulses to the target region and generate an acoustic reflector therein; measure reflections of the focusing ultrasound pulses from the acoustic reflector; based at least in part on the measured reflections, adjust a parameter value associated with one or more transducer elements so as to maintain and/or improve the ultrasound focus at the target region.