National Physical Laboratory

Thermal Test Object

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Thermal test objects

A thermal test object (TTO) can be used for general testing and research into temperature rises in ultrasound fields: they have previously been used in safety studies for diagnostic ultrasound and in performance studies for therapeutic applications.

A TTO is a closed container with an acoustically transparent window. It contains a thermal sensor sandwiched between pieces of tissue-mimicking material (TMM). Typically the sensor is a differential thermocouple, where the measurand is the temperature difference between the centre and the periphery of the thermocouple. TTOs can be constructed to mimic a soft-tissue environment or alternatively soft tissue next to bone; geometry and material properties can be customised to suit individual requirements. 

The overall design and performance of a TTO for medical diagnostic ultrasound fields is described in IEC 62306. We also supply agar-based tissue mimicking material for measurement of the surface contact temperature of transducers (IEC60601-2-37).

Contact the Instrumentation team for more information

Information on Acoustics