This type of shock wave therapy works like a WIFi signal. Radial Shock Wave therapy is most effective at its source, which means it stimulates the repair of tissues that can be positioned close to its applicator head/ 'tip-of-the-gun'.
So anything with thin skin surrounding the injured issues (heel bone, achilles tendons) are great areas. But something with lots of muscle, like a hip, could be better for this type of shock wave therapy.