A dual-mode ultrasound system provides real-time imaging and therapy delivery using a transducer array. The system may use various imaging modes to provide image data that may be used to select control points within an imaging field of view. The control points along with the image data may be used to solve an optimization problem to achieve desired focusing gains at one or more of the control points. The optimized solution may be used to produce excitation waveforms to generate new image data. The focusing gains may be evaluated and the optimization problem may be iterated until desired focusing gains are achieved. Virtual arrays may be defined and cascaded to provide flexibility in solving the optimization problem.