Ultrasonic detection of bubbles with doppler flow transducers

Doppler blood-flow transducers have been used to detect gas bubbles in the circulatory system during hyperbaric decompression. This paper describes briefly the theoretical acoustic scattering properties of bubbles and then describes various experimental procedures which have been used to determine the properties of these flow transducers. The capabilities and limitations of the transducers for the detection of bubbles were investigated by studying the scattering from both solid objects and air bubbles moving through the acoustic field. In vivo experiments indicate that it would be difficult to obtain any correlation between the output of these transducers and bubble size.