dual-energy X-ray absorptiometry

DEXA Scans: Debunking Body Scanning Myths

A DEXA scan is universally regarded as the gold standard for measuring body composition and has become keenly sought after by those with a serious commitment to get in shape.

But its historical association with clinical research facilities, sports science labs and hospitals has left some people with an impression that it is only for the likes of athletes, bodybuilders, the infirm or human lab rats. Because it uses X-rays, others believe DEXA is not safe.

Let’s debunk those theories now!

Myth 1: DEXA is unsafe

DEXA (which stands for dual-energy X-ray absorptiometry) measures body composition with a very low dose of X-ray. It’s true that unnecessary and excessive exposure to ionising radiation can be harmful and there are strict guidelines in the UK and around the world governing exposure to people from X-ray equipment.

But it is important to put things into perspective.

Every day in the UK, we are exposed to normal background radiation that comes from outer space, radon gas in the ground, materials used in buildings and from natural radioactivity in food. All that background radiation is the same as almost one-and-a-half DEXA body scans every day, such that in a year you are exposed to the equivalent of 540 scans.

Residents of Cornwall and Wales, where radioactive radon gas in the ground is very high, are naturally subjected to much higher doses – the equivalent of 1400 scans a year.

You can see now that the additional risk from a DEXA scan is tiny. You’ll be exposed to the same radiation if you eat 50g of Brazil nuts!

Myth 2: DEXA scans are invasive and claustrophobic

A DEXA scan is not to be confused with (and is nothing like) a CT or MRI scan. Both of these heavy-duty scanners have the well-known doughnut shape into whose central hole you are placed on a sliding stretcher.

An MRI scanner is deeper than a CT device and so the ‘tunnel’ is longer and darker, as well as narrower, making it very challenging if you are claustrophobic. An MRI scan may also require you to be strapped in to prevent movement and a CT scan might need you to be injected with a contrasting dye.

A DEXA scan couldn’t be more different. 

For a DEXA scan, you’ll lie on your back on a comfortable padded mattress and a scanning arm will pass over your body three times, never closer than about 30cm. No tunnels, noise or injections. The only preparation is to change into a gown or shorts and T-shirt and the whole process is over in less than four minutes.

Most people describe the DEXA experience as relaxing and many say they felt like nodding off (some do!)

Myth 3: You can’t have a DEXA scan with a Pacemaker or implants

Fears about Pacemakers, hearing aids, hip replacements, surgical plates and the like derive (like claustrophobia) from MRI scans. MRI uses strong magnetic fields and radio waves, so anything metal or electrical can be dangerous.

In contrast, the low-dose X-rays in a DEXA scan simply pass through, to varying degrees, whatever is on the table – fat, muscle, bone, jewellery, metal, silicone, etc.

It is best practice to remove what jewellery you can but there is absolutely no risk to the operation of a Pacemaker or any other devices and implants, and no risk to you either.

Myth 4: You need a clinician to interpret your DEXA report

Unlike a traditional medical X-ray, there is no need for a radiographer or radiologist to interpret the X-ray image from a DEXA scan and form an opinion. With DEXA, the information is contained in the data, which is printed immediately after the scan.

It’s true there is a lot of data (numbers) in the report and you will definitely benefit from having it explained to you; most people are not expecting the scan to be as comprehensive as it is. But a good body scan practitioner will not only interpret your results in plain English, they will also put the numbers into perspective by comparing your results to a big and broad population to give the data real meaning.

From there, they will help you set tangible targets for fat loss and muscle gain and a realistic timeline for you to achieve your goals.

Myth 5: DEXA scans are expensive

DEXA is a medical-grade technology and, for its superior accuracy, precision and consistency, it’s fair to say that you get what you pay for. But it’s probably not as expensive as you thought. A one-off baseline scan in the UK is about £170, while a package of four scans works out at less than £100 each.

DEXA is recommended every three months or so – long enough for a change in body composition to have occurred and to show you’re able to stick to the regime. Compared to fitness supplements, memberships and subscriptions, quarterly DEXA scans are an affordable and valuable addition to your fitness regimen.

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