Do medical scans or flying cause 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. 

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. The UK government regulates man-made ionising radiation to help reduce any health effects. 

Ionising radiation is different to the radiation from mobile phones, microwaves and radios. These use low energy radiation (non-ionising) and don’t cause cancer. 

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

Radiation from medical imaging (such as x-rays and CT scans) slightly increases the risk of cancer. 

About 6 in 1,000 cancers in the UK are linked to this type of radiation. But medical x-rays and scans are very important for diagnosing illnesses. The benefit of correctly diagnosing and treating health conditions outweighs any potential harm from the scan.  

The health risks from medical scans are low. Generally, the amount of radiation from medical imaging is less than what we are exposed to naturally over time. 

Other types of imaging that use ionising radiation include: 

• mammography (used for breast screening) 
• fluoroscopy (e.g. barium x-rays to look at the digestive system). 

Should I be worried about having medical scans?

Different types of medical imaging give out different amounts of radiation. For example, x-rays usually use less radiation than CT scans.  

The UK government sets guidelines on the amount of radiation used in medical scans so they are as safe as possible. Unborn babies are at higher risk from radiation so you will be asked if there is any chance you are pregnant. 

There are types of imaging that don’t use ionising radiation. This includes ultrasound and magnetic resonance imaging (MRI scan). But to diagnose some conditions an x-ray or CT scan is needed.  

Talk to your doctor if you have any concerns about having a medical scan. 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 unlikely to affect your risk of cancer. 

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

But this small amount of extra radiation does not affect the risk of cancer, even for frequent flyers. 

Do airport body scanners use radiation?

Not all scanners used at airports use ionising radiation. Some use non-ionising radiation, such as radio waves, which do not cause cancer.  

Airport body scanners that do use ionising radiation use a very small amount. There is no good evidence that these scanners increase the risk of cancer.