- Radiation from X-rays in dentist surgeries and hospitals
causes 700 people in Britain to develop cancer each year, researchers say
today.
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- Although medical X-rays help diagnose disease, they have
long been known to cause a small increase in the risk of cancer because
of the radiation they emit.
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- X-rays are the largest man-made source of radiation to
which the public is exposed, accounting for 14 per cent. Atomic testing
and discharges from nuclear power stations account for a fraction of that
figure, and most of the rest is natural radiation such as radon from granite
rocks.
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- Researchers from Oxford University (UK) and Cancer Research
UK estimated the size of the risk based on the number of X-rays carried
out in Britain and in 14 other countries.
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- According to their findings, published in the medical
journal The Lancet, the results showed that X-rays accounted for six out
of every 1,000 cases of cancer up to the age of 75, equivalent to 700 out
of the 124,000 cases of cancer diagnosed each year.
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- The calculations were based on the cancer rates among
Japanese survivors of the atomic bombs dropped on Hiroshima and Nagasaki
during the Second World War.
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- The UK had a lower risk from medical X-rays than most
of the other areas studied including Scandinavia, the Netherlands, Germany,
Australia and Japan. In Japan 30 of every 1,000 cases of cancer are thought
to caused by X-rays.
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- In the UK, the National Radiological Protection Board
(NRPB) has monitored the doses of radiation used in X-ray examinations
for more than a decade. Advancing technology has halved the dose used in
X-ray examinations since the early 1990s but the board found a 20-fold
difference between the doses delivered in different hospitals in its latest
review.
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- Concern has focused on the growing use of Computed Tomography
(CT) scans which take a series of X-ray pictures through the body and have
revolutionised the diagnosis of cancer and other diseases.
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- But according to the NRPB a single CT scan involves a
dose of radiation up to 1,000 times that of a chest X-ray.
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- Barry Wall, head of medical dosimetry at the NRPB, said:
'CT scanning is expanding so rapidly. The images are so fantastic that
not a lot of attention is being paid to the doses used.'
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- In a commentary on the findings, two German specialists
in radiology said that the authors did not consider the benefits of X-rays
in their study and offset those against the risks. 'Benefits include the
earlier detection of cancers by radiological examinations and the possibility
of early treatment,' they wrote.
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- But they said up to 30 per cent of chest X-rays might
not be necessary. They also said that unnecessary CT examinations could
cause radiation exposure. 'Those ordering radiological procedures should
think carefully about the benefit for and the risk to their patients for
each examination.'
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- http://www.medicalnewstoday.com/index.php?newsid=5618
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