An apparatus is configured to deliver destructive energy to a stone. The apparatus includes a detector operative to obtain image data from the stone, a generator operating according to one or more producing parameters for producing the destructive energy, and a video processor unit receiving the image data from the detector. The video processor unit is operative to analyze the image data to determine a displacement of the stone relative to a previous location of the stone. A controller linked to the video processor unit and to the generator is operative to vary the one or more producing parameters of the generator responsively to the displacement of the stone. Methods carried out by the apparatus are further provided.