Just to confirm the trend in guidance documents for end-users, on the same week that IEC published the guidance document for output tests and mantainance for ultrasound therapy equipment it published another document on mantainance, this time a general one.

IEC 62353 - “Medical electrical equipment - Recurrent test and test after repair of medical electrical equipment” provides guidance to mantainance tests and tests to be made after the repairing of medical electrical equipment.

But why these tests have to be made? This is a concept that not everyone understands.

When a medical electrical equipment is designed, it usually (by means of regulatory requirements) conforms to IEC 60601 series of standards. The problem is, after the equipment is sold (meaning post-marketing) it still has to comply with the standards. For the end-user to verify this, it´s generally agreeded that some tests are necessary (and the IEC series has documentation requirements for these tests to be declared by the manufacturer).

For the general standard, these tests are usually tests regarding electrical safety (leakage current, earthing and dielectric strenght to test insulation). It can be argued that these tests do not verify 100 % conformance with the standard, an the surely don´t, but to do that would require tests of the full standard, and this would certainly destrou the equipment :-). This problem is dealt with in IEC 62353, as the standard do not asks for the destructive dielectric strenght tests, but instead asks for insulation resistance tests which is a good way, and not a destructive one, to test the insulation.

I think this document (and the US one) are real trend in the safety assurance of medical devices. No other document of this type is being drafted on the IEC but i think they´ll be required in the future, at least for the most problematic types of devices (IEC has already published some documents of this type, for example the ones related to electrosurgical units and guidance for staff on the handling of medical equipment).

The following link has a preview (you can also buy the standard there too): http://webstore.iec.ch/Webstore/webstore.nsf/0/1A42D899896A37C8C12572DD000B92CE

Ultrasound physioterapy systems have a known and stablished problem regarding ouput measurement and calibration (see for example the three consecutive projects of PTB, TNO, NPL and others on the development of standards for US therapy equipment, funded by the EC Growth program [1], [2]. [3]). It affects both manufacturers and end-users. Guidance for manufacturers are already in place in international standard bodies and regulatory schemes.

Now it´s the time for the end-users. IEC published last week IEC/TS 62462 - Ultrasonics - Output Test - Guide for the maintenance of ultrasound physiotherapy systems
. This technical specification details methos for output measurement of US therapy equipment in the end-user (for example, hospital) setting, and also has guidance on stablishing a mantainance program for such equipment. The methods described are easy-to-use (in comparison with the appopriate methos used to characterise output, which are described in IEC 61689 and are expensive difficult to perform in a hospital setting).

This is not really the first of theses documents. This IEC document is based on an australian standard (i don´t remember the reference right now) and there´s also an IPEM report the same subject [4]. But this is the first international agreeded document on the subject.

The following link has a preview (you can also buy the standard there too): http://webstore.iec.ch/Webstore/webstore.nsf/0/D53F4042496E9127C12572DD000B93C3

[1]Hekkenberg RT
Characterising ultrasonic physiotherapy systems by performance and safety now internationally agreed.
Ultrasonics 1998 Feb; 36(1-5) :713-20.

[2] Hekkenberg RT, Beissner K, Zeqiri B, et al.
Validated ultrasonic power measurements up to 20 W.
Ultrasound Med Biol 2001 Mar; 27(3) :427-38.

[3]Hekkenberg RT, Richards A, Beissner K, et al.
Transfer standard device to improve the traceable calibration of physiotherapy ultrasound machines. Ultrasound Med Biol 2006 Sep; 32(9) :1423-9.

[4]IPEM Report 84 - ‘Guidelines for the Testing and Calibration of Physiotherapy Ultrasound Machines’, Bajram Zeqiri and Steve Pye