National Physical Laboratory

Thermochromic materials for the visualisation of thedistribution of time-averaged intensity within an ultrasonic field

Further Information

Published: 29 April 2013

Authors: Bajram Zeqiri, Ian Butterworth and Mark Hodnett

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Ultrasound is widely used for physiotherapy, treatment headstypically operating in the frequency range 1 to 3 MHz.

For safe and effective application of ultrasound, standards havebeen developed specifying key quantities such as the EffectiveRadiating Area, AER(IEC 61689).

The Beam Non-uniformity Ratio, RBN(IEC 61689), can be used to identify 'hot-spot' transducers. For physiotherapy treatmentheads, RBN must be less than 8.

Here, we describe a method that exploits a Thermochromic (TC) material to provide a rapid (currently qualitative) visualisation of the acoustic intensity distribution.

Last Updated: 25 Mar 2014
Created: 29 Apr 2013


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