CT for all – what’s not to like? Giles Maskell
We live in a society obsessed with imaging and images. The revolution in digital photography and the growth of social media and other forms of electronic communication have fuelled an explosion in the number of photographic images obtained, published, shared and stored.
T
he exquisite images of the human body obtained in the course of modern medical imaging retain for now a degree of mystique and are treated with a little more reverence, partly supported by the systems of information governance and confidentiality which pertain in healthcare. We should not expect this to last. How many 'baby albums' already contain an ultrasonic image of the
fetus in utero? Images of 'my fracture' are highly prized by teenage acquaintances, so how long can it be before images of 'my pneumonia', 'my hip replacement' and even 'my cancer' are in common currency? At the same time, clinical management has become ever more reliant on imaging investigations. The number of computed tomography (CT) scans performed in England has increased by an average of 10.3% every year for the past 10 years1
and the rate of increase shows no sign of slowing. Believe it or
not, we still lag behind other developed nations in the numbers of scans we perform so there is plenty of scope for further increase. The most recent comparative figures available from the Organisation for Economic Co-operation and Development (OECD) show the UK undertaking 77 CT scans per thousand population per annum. The OECD average for developed nations is 131 and towards the upper end of the scale, the figure for the USA is 2732
. Furthermore, there are powerful influences pushing us in the
direction of performing more scans. 'Early diagnosis', for example, is a phrase which has captured the imaginations of the public and of politicians particularly in relation to cancer3
, and in 2015, early
diagnosis basically means more scans. So what’s wrong with that? Is there any reason for us as imaging professionals – or for that matter as tax payers working in a publicly funded healthcare system – to be concerned? Traditionally, our concerns would have centred on the implications of exposure to ionising radiation. We work within a
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Our ability to detect 'abnormalities' on scans has far outstripped our knowledge of what they mean and what to do about them
legal and ethical framework which requires us to ensure that every exposure is justified, because we know from a large body of evidence that there is a risk to health associated with ionising radiation. The magnitude of that risk is usually quoted as increasing the lifetime risk of developing cancer by about 1 in 2000 for a standard CT examination of the torso4
of around one in three (going up to one in two according to a recent report5
. Each of us has a lifetime risk of developing cancer ) so the increased risk is
small for most of us. I would not for a moment suggest that we should ignore the risks, particularly in young people and those who may be at higher than average risk, but this is not the only problem, and not even the biggest problem. The real problem is that our ability to detect 'abnormalities' on scans has far outstripped our knowledge of what they mean and what to do about them. Modern CT scanners are extremely
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