Results of a Survey of Exposure Conditions used in Ultrasound Scans in the UK, February 2007

Abstract

The Safety Committee of BMUS (British Medical Ultrasound Society) carried out a survey of the output levels in common usage during normal clinical ultrasound scanning in the UK. The aim of this study was to gain a snapshot view of ultrasound scanning between 14 and 16 February 2007. BMUS members in ultrasound departments were invited to provide information for as many examinations as possible carried out on one of these days. Details about the type and duration of examination, transducer frequency, scan mode and the safety indices (mechanical index, MI, and thermal index, TI) displayed were requested. Users were asked to record the starting and finishing MI and TI, and the highest level that each reached during an examination (MImax and TImax). They were also requested to provide information about the type of TI being displayed (TIB–bone thermal index, TIS–soft tissue thermal index, TIC–cranial thermal index). 309 examinations, carried out on 60 different ultrasound machines, were reported. The longest scan time used was 34 minutes, Mechanical Indices in the range 0·1–1·6 and Thermal Indices up to 2·5 were reported. All examinations, apart from three, fell within the safety guidelines published on the BMUS website.