Shock waves are always generated extracorporeally, i.e. from outside the body, and then coupled into the body in a defined area through the skin. They pass the tissue and are directed exactly to the stone which shall be destroyed.

Shock waves can be generated by different methods :

1. by electrical discharge under water by an electrode which functions in principle like the spark plug of a car.

2. piezoelektrically by electric stimulation of piezoelectirc crystals

3. electromagnetically by an electric pulse passing through a flat electric coil.

A machine for the generation of shock waves at the Institute for Surgical Research of the University of Munich is shown in the above figure. It is not suited and approved for patient treatment.