Do medical scans and air travel cause cancer?

  • High energy ‘ionising radiation’ can cause cancer
     
  • Some medical scans, including x-rays, expose us to small amounts of ionising radiation. But the health risks are low and usually outweighed by the benefit of getting the right diagnosis
     
  • Flying and airport body scanners are unlikely to increase the risk of cancer

What types of radiation could cause cancer?

High energy (ionising) radiation can cause cancer if a person is exposed to a lot of it. This is because it can affect our cells and damage our DNA.

Ionising radiation is different to the radiation given off by mobile phones, 4G and radios. These sources use much lower energy radiation and don’t cause cancer.

We are naturally exposed to a small amount of ionising radiation every day. The main source in the UK is radon gas from the ground.

There are also man-made sources of ionising radiation, including x-rays. To help avoid the possible health effects of ionising radiation, man-made exposures are tightly regulated in the UK.

 

Can X-rays and CT scans increase the risk of cancer?

There is evidence that radiation from medical imaging (such as x-rays) slightly increases the risk of cancer.

About 6 in 1,000 cancers in the UK are linked to this type of radiation. But the health risks are much lower than the risks of medical conditions if they are not diagnosed and treated correctly.

Medical x-rays and other types of imaging are very important to help diagnose different illnesses – from broken bones to cancer.

Other types of imaging that use ionising radiation include mammography (used for breast screening) and fluoroscopy (e.g. barium x-rays to look at the digestive system).

The amount of radiation from medical imaging is usually less than we would be exposed to naturally over time.

 

What else affects risk from x-rays?

Different types of medical imaging give out different amounts of radiation. The level of risk from the radiation you receive will depend on:

  • The type of scan you have – for example x-rays usually use less radiation than CT scans
  • The area of the body being scanned – for example dental x-rays pose a lower risk than chest x-rays
  • Age – young patients are at more risk. Unborn babies are also at higher risk so you will be asked if there is any possibility you are pregnant

 

Should I be worried about having x-rays?

In the UK, the government estimates the amount of radiation received from different types of x-rays and sets guidelines to make sure they are as safe as possible.

Your doctor might recommend another type of imaging that doesn’t use radiation, for example 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 the number of x-rays you’ve had, you should talk to your doctor. You should also tell your doctor about any previous x-rays you have had as this may mean that you do not need to have more.

For information on radiation used in cancer treatment, read our page on radiotherapy

 

Can radiation from flying cause cancer?

Travelling by plane is one of safest ways to travel and is unlikely to affect your risk of cancer.

There is ‘cosmic’ radiation in space, but the earth’s atmosphere shields us from most of this. The atmosphere thins the higher you get, so someone flying in a plane would receive more cosmic radiation than someone on the ground.

A passenger would get a very small extra amount of radiation, but this is unlikely to affect their cancer risk, even if they were a frequent flyer.

 

Do airport body scanners use radiation?

Some airport body scanners use very small amounts of ionising radiation. There are 3 types of scanners:

  • Millimetre wave scanners- these use radio waves, which are a form of non-ionising radiation and do not cause cancer
  • Backscatter and transmission x-rays - these use x-rays which are a form of ionising radiation, but a much lower amount than in a medical scan

None of these scanners have been shown to increase the risk of cancer. 

IARC. Ionizing Radiation. X- and Gamma gamma-Radiation. 2018. Available from: https://monographs.iarc.fr/wp-content/uploads/2018/06/mono100D-7.pdf. Date Accessed: October 2020.

PHE. Ionising radiation: dose comparisons. 2011. Available from: https://www.gov.uk/government/publications/ionising-radiation-dose-comparisons/ionising-radiation-dose-comparisons. Date Accessed: October 2020.

Berrington de González A, Darby S. Risk of cancer from diagnostic X-rays: estimates for the UK and 14 other countries. Lancet. 2004;363(9406):345-51.

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