Apparatus includes a treatment bag configured to at least partially encapsulate a body portion to be treated, the treatment bag being generally leak-proof and transparent to acoustic waves and at least partially filled with a shockwave transmission liquid. An acoustic wave device includes a transducer operative to generate acoustic waves. A focusing device focuses the acoustic waves toward a focus. The acoustic wave device is placed near or against the treatment bag and arranged with respect to a target in the body portion, which it is desired to treat, so that the acoustic waves generated by the transducer propagate towards the focus via the shockwave transmission liquid in the bag.