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Medical x-rays and cancer

Doctor looking at a chest X-rayMedical x-rays are a very important tool for diagnosing different illnesses, including cancer. The health risks from x-ray radiation are generally very low and usually outweighed by the benefits of getting the right diagnosis and appropriate treatment.

We are exposed to low background levels of radiation all the time. The dose received from medical x-rays is usually less than what we'd be exposed to naturally over a few days or years (depending on the type). But even so, unnecessary x-rays should be avoided.

What are x-rays?

X-rays are a form of high-energy ionising radiation that can damage DNA in our cells, and at high doses can cause harm. This damage has the potential to lead to cancer, but because medical x-rays only use small amounts of radiation, the risks involved are generally low.

Common types of medical x-rays

There are different types of medical imaging tests using x-rays that you may come across:

  • radiography to look at broken bones or your teeth and chest
  • mammography to screen for breast cancers
  • computed tomography (CT) to detect different diseases, including some cancers
  • fluoroscopy, such as a barium x-rays to look at your digestive system


How much radiation?

These tests all involve different amounts of radiation. The level of risk from the radiation you receive will also depend on:

  • The area of the body - for example x-rays of the chest pose a lower risk than x-rays of the pelvis
  • Age - young patients are at more risk. Unborn babies are also at higher risk so you should tell your doctor if you are pregnant
  • Gender - women have a slightly higher lifetime risk of developing radiation-induced cancers than men

In the UK, the Health Protection Agency monitors the amount of radiation we receive from x-rays and makes sure they are as safe as possible. The average radiation dose now is half the level it was in the 1980s. You can find out more about radiation from medical x-rays on the Health Protection Agency website.

Avoiding unnecessary x-rays

Clinically relevant x-rays are very important.

When possible, your doctors will recommend other types of imaging that don't use radiation, for example using ultrasound or magnetic resonance imaging (MRI scan). But in some cases an x-ray is the best way to do the job.

If you are concerned about having a large number of x-rays, you should talk to your doctor about it. You should also tell your doctor of previous x-rays you may have had. They may be useful for diagnosing, managing or treating your current condition. And they may mean that you do not need to have more x-ray tests.

Be careful about commercially available medical scans.

Some commercial companies offer ‘full body’ CT scans to the public. These generally cover your chest, abdomen and pelvis. These scans are likely to do more harm than good for people without medical symptoms.

They may diagnose conditions which would never have caused you any problems and may lead to unnecessary treatment. A ‘full body’ CT scan also uses 500 times the amount of radiation of a single chest x-ray. This may be necessary for people with a genuine medical need. But for healthy individuals without medical symptoms, the risks generally outweigh the benefits.

A sense of perspective

We are exposed to radiation from natural sources every day. Radon gas from the earth’s crust contributes the largest amount of natural radiation to most people living in the UK. Cosmic rays from the sun, stars and outer space, natural radiation from the food we eat, the water we drink and the ground we walk on, also contribute to our natural exposure every day.

Although medical x-rays add some extra radiation on top of this, they can also bring great benefits to patients, by leading to accurate diagnosis and effective treatment.

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Question about cancer? Contact our information nurse team
Updated: 30 October 2014