A general design for a thermal test object (TTO) is proposed. A number of n
ovel features make the design particularly suitable for use as a standardis
ed device for assessing the heating capability of diagnostic ultrasound bea
ms, To assess performance, soft-tissue TTOs have been made containing thin-
film thermocouples sandwiched between discs of tissue-mimicking gel. Instal
led in an appropriate measurement system, these TTOs exhibit excellent ther
mal and spatial resolution, allowing the ultrasound beam to be located rapi
dly and reproducibly. The measured temperature rise after 3 minutes of heat
ing has been compared with theoretical predictions based on measured pressu
re distributions, and agreement is within 10%. Other studies have shown tha
t soft-tissue- and bone-mimicking TTOs can be used to evaluate a wide range
of ultrasound fields and that different physical tissue models can be simu
lated. It is concluded that this design would be suitable for providing ref
erence assessments of the thermal hazard posed by diagnostic ultrasound und
er standardised conditions. Crown copyright. Reproduced by permission of th
e Controller of HMSO.