Relative transmission of ultrasound by media customarily used for phonophoresis.

The purpose of this study was to determine the relative transmission of ultrasound by the media commonly used by physical therapists to apply phonophoresis. The relative transmission of ultrasound energy through various phonophoresis media was compared with that of degassed water, which is the ideal standard. Transmission was assessed by placing a thin layer of the test medium on the transducer of a therapeutic ultrasound unit and measuring delivery of ultrasound with an ultrasound power meter. The media evaluated produced two significantly different groups of transmission results: (1) transmission greater than 80% of that of water and (2) transmission less than 40% of that of water. Media that optimize the therapeutic efficacy of phonophoresis in both clinical and experimental settings are discussed.