Ultrasonics

In medicine and technology ultrasound is being applied in a large and increasing range of applications. During cleaning or emulsification, prenatal investigations, and distance determination during car parking, ultrasound may or must penetrate the human body. Up to now, not all interaction mechanisms between ultrasound and tissue have completely been understood and the question arises under what circumstances ultrasound may have hazardous effects on the human body.

To estimate the potential risk of ultrasound treatment, it is necessary to determine of the sound field parameters. The Ultrasonics Section provides the metrological basis for this task and itself carries out measurements. So the determination of ultrasonic power and sound pressure are of particular importance.

The measurement of these parameters is not in all cases possible by standard techniques. In the Section novel measurement techniques such as fiberoptic sensors are developed that, for example, can detect the sound field in the focus of a lithotripter. Lithotripters are used for the disintegration of stones in medicine.

In the Ultrasonics Section measurement techniques have been established which serve to characterise the effect of ultrasound on the human body. An important parameter is the increase in temperature in the tissue during an ultrasonic treatment. With the aid of fiberoptic sensors and electrical thermocouples, the temperature increase in tissue occurring during the application of various surgical instruments could be measured under real treatment conditions. The fiberoptic sensor simultaneously provides even both the sound pressure and the temperature increase with high spatial and temporal resolution.

Medical diagnostics using ultrasound are commonly applied. Although it is in general a safe method, special applications may cause a serious temperature increase in tissue. The Ultrasonics Section takes part in international activities to provide methods and techniques to estimate the potential risk during ultrasound treatment. Thus a contribution will be made to responsibly handling of ultrasound in diagnostics.

During the technical application of ultrasound such as, for example, in cleaners, a large amount of airborne ultrasound is emitted into the surroundings. These sound waves may reach staff or people not involved, and not much is known about the potential of ultrasound to harm the human ear. The Ultrasonics Section is concerned with extending this knowledge and establishing protective regulations on the national and international level.