The new British Medical Ultrasound Society Guidelines for the safe use of diagnostic ultrasound equipment

Abstract

Diagnostic ultrasound has an excellent safety record, with no evidence to date for harm arising from human exposure. It is, however, still the responsibility of the person carrying out the ultrasound examination to conduct it in a safe manner. This entails drawing on a good knowledge of the machine settings and their effect on potential bio-effects to control the output of the scanner. Most international professional ultrasound societies regard the giving of guidance for the continued safe use of diagnostic ultrasound to be of sufficiently great importance to have established their own safety committees, giving them the remit of providing advice to the society’s membership on this topic. While most of these committees have drawn up their own separate clinical safety statements, the content of these is, unsurprisingly, generally similar. Few societies, however, have issued application specific guidelines for the conduct of ultrasound examinations, and it is only the British Medical Ultrasound Society (BMUS) that have made detailed recommendations about exposure times. The new BMUS Guidelines for the safe use of diagnostic ultrasound equipment were developed by BMUS’s Safety Committee. Their basis lies in their original guidelines (written in 2000), which introduced recommended maximum times for exposure during obstetric examinations. When first published, this was an innovative move that has since gained widespread acceptance. Two types of safety index can be displayed on the scanner screen, one concerned with potential heating (the thermal index, TI) and the other with mechanical (mainly cavitational) events (the mechanical index, MI). MI is of most concern when microbubble contrast agents are being used. For the majority of ultrasound examinations, especially in obstetrics, it is the potential for inducing a temperature rise that is of most concern on safety grounds. The recommended exposure times are therefore linked with upper limits of TI. The BMUS Committee was concerned that many practitioners had not read, or, if they had, did not remember, the guidelines in their previous incarnation. This new version represents an attempt to render them more ‘user friendly’. The new guidelines have been formulated in three sections: