National Physical Laboratory

Measurement of therapeutic ultrasound fields

Hydrophone field mapping facility
Hydrophone field mapping
facility

NPL Acoustics offers wide ranging and traceable measurement, R&D, design and consultancy services for medical ultrasound in the range 0.7 to 40 MHz. We have the capability and facilities to characterise complex devices such as multi-element phased arrays used for high intensity therapeutic ultrasound (HITU or HIFU). Using our range of unique measurement tools we can provide a complete solution for manufacturers, developers and users of therapeutic ultrasound equipment.

Hydrophone field mapping

We perform field measurements in a dedicated scanning tank using a range of membrane, needle and fibre optic hydrophones. Special acoustic attenuators allow us to characterise transducers driven at clinical levels.
(IEC 62127, IEC 61689, IEC 62556)

Acoustic power measurement using the buoyancy change method
Acoustic power
measurement using the
buoyancy change method

Acoustic power

We measure acoustic output powers from 5 mW up to at least 500 W by radiation force and by the NPL buoyancy change method developed for strongly focused fields. We can also measure electrical power into transducers in real time to calculate transducer efficiency.
(IEC 61161 and IEC 62555)

Thermal field mapping

Our thermal imaging system rapidly scans complex acoustic fields in 3-D, to map the intensity distribution by measuring the heating pattern produced in a thin absorber.

Composite thermal image of the field of a multi-element phased array showing 6 focal points
Composite thermal
image of the field of
a multi-element
phased array showing
six focal points

Temperature rise

We measure ultrasound induced temperature rise in thermal test phantoms using thin film thermocouples and tissue mimicking gels. Phantoms (including material properties) can be customised to suit individual requirements.
(IEC 62306)

Modelling

We model transducers and acoustic fields for applications including device design and optimisation, propagation of ultrasound through different media and prediction of temperature rise in tissues.

Standards

Thermal test phantom
Thermal test phantom

We are active in the development of International Electrotechnical Commission (IEC) standards and can provide information on current measurement and safety requirements and likely future developments.

See all our Measurement Services

Last Updated: 24 Aug 2016
Created: 14 Oct 2014

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