This disclosure provides systems and methods for fast ultrasound treatment. The systems and methods can involve a treatment device including a housing, a transducer module, and a control module. Energy emitted from an energy source of the treatment device can pass through an acoustic window having a non-zero radius of curvature. The treatment device can be moved along a target surface while retaining contact between the acoustic window and the target surface. Coupling between the energy source and a region of interest can be retained upon a change in an angle of incidence of the energy relative to the target surface.
