WG 7 - TC 87/WG 7

IEC 61847:2025 specifies:
– the essential non-thermal output characteristics of ultrasonic surgical units;
– methods of measurement of these output characteristics;
– those characteristics to be declared by the manufacturers of such equipment.
This document is applicable to equipment which meets the criteria of a), b) and c) below:
a) ultrasonic surgical systems operating in the frequency range 20 kHz to 120 kHz; and
b) ultrasonic surgical systems whose use is the fragmentation, emulsification, debridement, or cutting of human tissue, whether or not those effects are delivered in conjunction with tissue removal or coagulation; and
c) ultrasonic surgical systems in which an acoustic wave is conducted by means of a specifically designed wave guide to deliver energy to the surgical site.
This document is not applicable to:
– lithotripsy equipment which uses extracorporeally induced pressure pulses, focused through liquid conducting media and the soft tissues of the body;
– surgical systems used as part of the therapeutic process (hyperthermia systems);
– surgical systems whose mechanism of action is through frictional heat generated by tissue in contact with the wave guide, e.g. clamp coagulators or clamping vibrational cutters;
– surgical systems whose mechanism of action is through focused ultrasound for either thermal degradation (high intensity focused ultrasound – HIFU or HITU) or cavitation erosion (Histotripsy) of tissue remote from the ultrasound transducer;
– surgical systems whose mechanism of action is through erosion of hard tissues in contact with the applicator tip, e.g. bone cutting or drilling.
This document does not deal with the effectiveness or safety of ultrasonic surgical systems. This document does not deal with airborne noise from the systems, which can affect operators and patients.
IEC 61847:2025 cancels and replaces the first edition published in 1998. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) The upper frequency covered by this document has been raised from 60 kHz to 120 kHz.
b) The hydrophone method of measuring ultrasound power is now normative. Because of difficulties in using the calorimetry method of measuring ultrasound power, it is no longer the primary approach.
c) It is recognised that some systems can have more than one mode of vibration under user control, and the measurement techniques and declarations have been updated to address this.
d) The high-frequency component, which relates to cavitation developed at the applicator tip and the vibration amplitude at which cavitation occurs is addressed.
e) Specific requirements for measurement at excursion levels where no cavitation is present, and extrapolation to maximum excursion level(s) are described.
f) Guidance is provided to adapt the methodology described to more complex designs and vibration patterns, excursion directions, and their output characteristics.
g) Guidance is provided with respect to measurement tank arrangements for different types of systems.
h) The list of ultrasound methods and systems not covered by this document was extended to incorporate recent developments.
i) Definitions for cavitation related terms were added.
j) Requirements for the measurement of directivity characteristics of the applicator tip were changed.
k) Annex A was modified and Figure A.1 was added.
l) New literature was added, and the references to other standards were updated.

IEC 61846:2025 is applicable to:
– therapy equipment using extracorporeally induced focused pressure pulse waves;
– therapy equipment producing focused mechanical energy excluding thermal energy.
This document does not apply to percutaneous and laser lithotripsy equipment.
This document does not apply to:
– histotripsy or other therapeutic ultrasound bursts of longer time duration than that of the pressure pulse;
– non-focused pressure pulse equipment.
This document specifies:
– measurable parameters which could be used in the declaration of the acoustic output of extracorporeal focused pressure pulse equipment;
– methods of measurement and characterization of the pressure field generated by focused pressure pulse equipment.
While this document has been developed for equipment intended for use in lithotripsy, it has been developed such that, as long as no other specific standards are available to be used for other medical applications of therapeutic extracorporeal focused pressure pulse equipment, this document can be used as a guideline.
IEC 61846:2025 cancels and replaces the first edition published in 1998. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) Change of title: "pressure pulse lithotripters" in the previous edition is changed to "therapeutic focused short pressure pulse sources" in order to take into account the development in the relevant technical and biomedical applications of such sources, which were originally used only for (kidney) lithotripsy, while recent applications include a wide range for the treatment of, for example, stone diseases, orthopaedic pain, tissue, cardiac and brain diseases.
The term "focused" was added to differentiate IEC 61846 from IEC 63045.
The term "short" was added to align the nomenclature to IEC 63045 and to differentiate IEC 61846 from standards in the HIFU and HITU fields.
b) Clause 1 and elsewhere in the document: The term "lithotripsy" is changed to "therapy" in order to account for the wide range of applications beyond stone diseases.
c) Clause 3: The "−6 dB" parameter definitions are replaced by "−n dB" to avoid misconceptions in the significance and use of these parameters and to account for newer findings in literature.
Additional "n MPa" parameters are introduced for the same reasons.
The definitions of "derived" parameters are aligned to those in recently published standards, for example IEC 62127-1.
New definitions were added which describe parameters appearing in newer relevant literature, for example "momentum", "average positive acoustic pressure", "cavitation induction index", "pulse to pulse variability", "total pressure pulse energy dose".
d) Clause 6: The terms "focus hydrophone" and "field hydrophone" were removed to account for newer technical developments. New terms distinguish between "hydrophones for pressure pulse measurements" and "hydrophones for quality assurance".
e) Annexes: Descriptions, tables and figures were edited to account for newer literature and standards as well as technical developments.

IEC 63045:2020 is applicable to
– therapy equipment using extracorporeally induced non-focused or weakly focused pressure pulses;
– therapy equipment producing extracorporeally induced non-focused or weakly focused mechanical energy,
where the pressure pulses are released as single events of duration up to 25 µs.
This document does not apply to
– therapy equipment using focusing pressure pulse sources such as extracorporeal lithotripsy equipment;
– therapy equipment using other acoustic waveforms like physiotherapy equipment, low intensity ultrasound equipment and HIFU/HITU equipment.
This document specifies
– measurable parameters which are used in the declaration of the acoustic output of extracorporeal equipment producing a non-focused or weakly focused pressure pulse field,
– methods of measurement and characterization of non-focused or weakly focused pressure pulse fields.
This document has been developed for equipment intended for use in pressure pulse therapy, for example therapy of orthopaedic pain like shoulder pain, tennis elbow pain, heel spur pain, muscular trigger point therapy, lower back pain, etc. It is not intended to be used for extracorporeal lithotripsy equipment (as described in IEC 61846), physiotherapy equipment using other waveforms (as described in IEC 61689) and HIFU/HITU equipment (see IEC 60601 2-62 and IEC TR 62649).

Applies to - lithotripsy equipment using extracorporeally induced pressure waves; - lithotripsy equipment producing focused mechanical energy. Specifies - measurable parameters which could be used in the declaration of the acoustic output of extracorporeal lithotripsy equipment, - methods of measurement and characterization of the pressure field generated by lithotripsy equipment.

This standard specifies: - the essential non-thermal output characteristics of ultrasonic surgical units; - methods of measurement ot these output characteristics; - those characteristics which should be declared by the manufacturers of such equipment. This standard is applicable to equipment which meets the requirements of a, b and c below: a) ultrasonic surgical systems operating in the frequency range 20 kHz to 60 kHz; and b) ultrasonic surgical systems, whose use is the fragmentation or cutting of human tissue, whether or not those effects are delivered in conjunction with tissue removal or coagulation; and c) ultrasonic surgical systems, in which an acoustic wave is conducted by means of a specifically designed wave guide to deliver energy to the surgical site.