The present invention provides for a method for continuously monitoring a coupling quality of a coupling interface between an acoustic energy source of a therapeutic device and a body surface area of a patient, comprising the steps of: (f) obtaining a plurality of images of at least one predetermined first area of the coupling interface; (g) extracting at least one first image characteristic of a predetermined first image of said plurality of images; (h) extracting said at least one first image characteristic of at least one second image of said plurality of images, said at least one second image being temporally spaced apart from said predetermined first image; (i) determining a quantitative parameter corresponding to a difference between said at least one first image characteristic of said predetermined first image and said at least one first image characteristic of said at least one second image, and (j) actuating a signal if said quantitative parameter exceeds a predetermined reference threshold.