November 17, 2011

scientific reaction to ban on further trials of back scatter body scanners in EU airports

Radiation safety experts provided comments on this announcement about scanning equipment currently being trialled in the UK.

Dr David Sutton, Head of Radiation Physics at Ninewells Hospital & Medical School, Dundee and Fellow of the Institute of Physics and Engineering in Medicine , said:

“The equipment presently being trialled in the UK delivers a radiation dose per scan that is more than 100,000 times less than the average dose to a member of the public from naturally occurring radiation and medical exposures. Even if three scans are required the radiation dose will still be 30,000 times less than the UK average dose and almost 1000 times less than the dose received during a transatlantic flight – which is relevant as the scanners are at airports. This level of radiation dose is extremely low.”

Prof Malcolm Sperrin, Director of Medical Physics at Royal Berkshire Hospital and Fellow of the Institute of Physics and Engineering in Medicine, said:

“The science behind this technique is that human tissue absorbs and backscatters X-rays to a different extent than metal objects. Hence this is a useful tool for detecting the presence of such objects as guns or other similar articles.

“It is accepted to be the case that X-rays have a potential for interacting with tissue and causing a health risk but the risk is currently thought to be proportional to how much X-ray energy is absorbed. This is the crucial point here – the intensity of the X-rays will be extremely low meaning that any health risk is correspondingly extremely low and hence the benefit of detecting dangerous articles will very significantly outweigh any risk.

“Whilst it is true that there is a governing principle of ‘do no harm’, the consequences of missing a gun or similar device is of sufficient magnitude to warrant the use of X-rays in applications such as this and appropriate risk analysis will certainly have taken place.

“In the case of parents worried about irradiating milk, once the X-rays have stopped there is no residual radiation – in just the same way as turning off a domestic light bulb leaves the room dark.”