Ultrasound waves are generated by crystals oscillating rapidly in an alternating electrical field and have a frequency range of over 20 kilohertz – higher than the human ear can detect.

During a medical ultrasound examination, also termed sonography, a so-called transducer emits the sound waves as well as receiving the sound which is reflected back. A gel allows the high-frequency ultrasound waves to enter the body more easily. Once inside the body they hit different kinds of tissue: air, bones and other mineralised tissues absorb ultrasound almost completely. Consequently, this diagnostic procedure is not suitable for examining the skeleton or the lungs.

Finally, the ultrasound waves return, similar to an echo, and provide three important pieces of information: how long did they travel? How much energy did they consume? From which direction did they come? The computer uses this data, which is provided by a pattern of sound reflection, to generate a two-dimensional image in a matter of seconds.

New ultrasound equipment can even provide three-dimensional images. These 3D pictures, upon which the finest of structures can be discerned, are especially helpful for the exact medical observation of unborn babies in the womb. Ultrasound is not only used for diagnosis, however, but can also be employed for treatment. The sound waves make it possible to carry out very precise operations without destroying too much tissue. In addition, patients undergoing ultrasound treatment are spared painful wounds and scar formation.

The transducer is the most essential part of ultrasound treatment equipment. It can, for instance, destroy a tumour by bundling sound waves at a point which is calculated exactly beforehand. The temperature at this point rises to up to 90 degrees – and with every “shot” several millimetres of the malignant tissue are burnt.Patients with kidney stones are also frequently treated with ultrasound. The shock waves shatter the stone whilst the procedure itself is very gentle on the patient.