This technical specification is applicable to high intensity therapeutic ultrasound (HITU) devices, specifying: – relevant parameters for quantifying the field; – measurement methods at relatively low output levels and methodology for extrapolating these to higher therapeutic level fields; – consideration of sidelobes and pre-focal maxima; – parameters relevant to HITU transducers of different construction and geometry, including non-focusing, focusing with or without lenses, collimated, diverging and convergent transducers, multi-element transducers, scanning transducers and multiple sources. This technical specification is intended to support the ultrasonic measurement requirements given in IEC 60601-2-62. These specifications would have use in quality assurance, safety testing, and the standardization of communications regarding the clinical performance of HITU systems. Where possible, this technical specification incorporates specifications from other related standards. This technical specification does not apply to the following types of devices, which are covered by other standards: – lithotripters (see IEC 61846); – surgical equipment (see IEC 61847); – physiotherapy devices (see IEC 61689). Throughout this technical specification SI units are used. In the specification of certain parameters, such as beam-areas and intensities, it may be convenient to use decimal multiples or sub-multiples. For example, beam-area may be specified in cm² and intensities in W/cm² or mW/cm².