A source of therapeutic acoustic waves for minimally invasive treatment of internal body regions with the therapeutic acoustic waves has a number of source parts which emit the acoustic waves. In order to be able to apply the source easily in the inside of the body in a simple way, source parts are arranged so as to be foldable in an introduction position giving the source a relatively small cross section as viewed in the introduction direction. After introduction into a patient the source parts are unfolded into a working position.