ABSTRACT
The wavelength in soft tissues, in which the speed is about 1540 m/sec, is about 1.54 mm at 1 MHz and proportionately shorter at higher frequencies. The wavelength is one of the factors that control the spatial resolution of ultrasonic imaging. In abdominal scanning, for example, a resolution of a millimeter or better is needed, so that frequencies of 1.5 MHz or higher are necessary.
