This Technical Specification is applicable to medical diagnostic ultrasonic fields. This Technical Specification establishes: – the important characteristics and terminology for test objects containing an embedded thermal sensor to determine ultrasonic heating; – requirements for defining particular types of test object for specific applications; – examples of design features which will ensure that the performance specifications are achieved; – validation procedures; – general test methods for using test objects to determine standardised temperature rises. NOTE 1 This Technical Specification specifically relates to test objects which contain an embedded thermal sensor (such as a thermocouple or thermistor). Although it may be possible to use non-embedded methods of temperature determination to achieve the same ends, these are outside of the scope of this Technical Specification. NOTE 2 The test objects specified in this Technical Specification are for the measurement of temperature rise and not for the determination of Thermal Index which is, by definition, an algebraic combination of acoustical field quantities and is therefore not a physically measurable quantity.