Never a day goes by, it seems, without a media headline screaming about some poor person who felt perfectly well one day and was found to be riddled with cancer the next. At the same time, we are bombarded with junk mail telling us about this or that gadget or gizmo that we can't live without. Now private health firms are getting in on the act. At the moment, 90% of scans of the body are carried out on the NHS. But more and more private companies are offering 'total MOTs' which include private body scans for people who feel well. Should we be reassured, or is there a risk not just to our bank balances but also to our health from these scans?
Body scans - what they are
There are lots of different sorts of scan, but the most common is the computerised tomography (CT) scan. Magnetic resonance imaging (MRI) scans are less commonly offered in the UK for private screening. CT scans are special X-rays that take hundreds of X-ray images at different angles through your body. Together, these provide X-ray images of 'slices' through your body at different points. Unlike normal X-rays, they offer detailed views of your organs (liver, lungs etc), large blood vessels, brain and nerves, as well as your bones.
Radiation in perspective
Nuclear power plant accidents, nuclear bombs and even a passing interest in horror films of the 'killer mutant' variety remind us that radiation (or more specifically, ionising radiation) can damage our bodies. Ionising radiation is high-frequency radiation. It has enough energy to damage the DNA in cells by knocking electrons off (ionising) them. This can lead to cancer in later life. We can't avoid it completely - the average Briton is exposed to 2.7 mSv (millisieverts) a year, much of it from natural radioactivity in everything from cosmic rays in the solar system to radon gas from the ground seeping into buildings.
The debate about how much ionising radiation is 'safe' has raged for years, but there is little we can do about natural background radiation and we do know that while we're all exposed to it, we don't all succumb to cancer at an early age. In fact, carefully targeted ionising radiation is widely used to treat cancers. But there's no doubt that higher doses of ionising radiation in the long term do increase your cancer risk, while very high doses can be fatal. It makes sense, then, to avoid unnecessary exposure.
Because CT scans take multiple X-rays, the dose of radiation you're exposed to is much higher than with 'normal' X-rays. For instance, a standard chest X-ray exposes you to 0.02 mSv, while a CT scan of the same area involves 6.6 mSv. A whole body CT scan involves about 10 mSv - almost four times the amount of ionising radiation you would be exposed to over a whole year in normal life.
Private scans - the risks
All private scans are expensive, many costing hundreds of pounds. MRI scans are usually much more expensive than CT scans, because the equipment is newer and more sophisticated.
With a single CT scan, the dose of radiation is relatively low, and these scans have revolutionised our ability to diagnose some medical conditions. As a one-off investigation for a single part of the body, the benefits almost always outweigh the risks. However, if you have a CT scan regularly (say, every five years) the amount of radiation builds up. COMARE, the commission asked to look into the value of these scans, estimates that if 100,000 people have five-yearly scans from age 40-70, 240 people will die from cancer as a direct result of the radiation from the scans.
False positives - a risk to your peace of mind
Some scans may pick up changes which they detect as being abnormal when in fact they are nothing to worry about. You will be given the worrying news that a problem has been found and will go through all the stress (and possible risks) of having further tests to check it out.
A false sense of security?
You might think that getting the 'all clear' would bring you peace of mind. In fact, there's evidence that this reassurance is short-lived, and many people start worrying again within months. What's more, a 'normal' result may allow you to kid yourself that your smoking, excess drinking or other bad habits aren't doing you any harm. That in turn could weaken your resolve to tackle your unhealthy lifestyle. And that could kill you more surely than the radiation.
With thanks to 'My Weekly' magazine where this article was originally published.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.