Experts are to investigate whether magnetic
resonance imaging (MRI)
scanners can damage health.
The Health Protection Agency (HPA) study is likely
to focus mainly on the impact on health workers who
regularly operate the machines.
MRI scans have been hailed as a significant step forward
in the diagnosis of medical conditions.
But there is concern exposure to the magnetic fields
they create may produce adverse long term health effects.
Sir William Stewart, HPA chairman, said: "MRI scanning
has some undoubted benefits in medicine, especially
as an aid to accurate clinical diagnosis.
"However we need to bear in mind that the magnetic
fields produced by the machines are quite substantial
and that these fields are increasing in order to achieve
improved clarity of image.
"The exposures to patients and medical staff from
the magnetic fields can be high and there is a shortage
of information on possible adverse long term health
effects."
The announcement follows a recommendation by an independent
board of experts, which said there was a pressing need
to investigate whether regular exposure to the magnetic
fields produced by MRI scanners could raise the risk
of cancer and other diseases.
Clear images
MRI, first developed 30 years ago, is based on a well
established scientific technique, nuclear magnetic resonance,
which uses the interaction of magnetic fields with the
spin of the nuclei of atoms to provide detailed information
on the constituents of chemicals and biological materials.
The technique can provide excellent, detailed images
of the body's soft tissue and is an alternative to using
X-ray techniques such as computed tomography (CT).
MRI does not use ionising radiation and this can be
a distinct advantage for examinations of children or
for abdominal examinations where radiation doses can
be high.
However, MRI requires large magnetic fields for successful
scanning - bigger than those commonly used in industry.
The European Parliament was due to vote on new rules
to limit exposure to powerful electromagnetic fields
earlier this year.
But following advice from doctors, who said the proposed
limits were so low they could prevent the use of MRI
scanners, the issue was placed on the back burner.
