People are often concerned about being exposed to radiation during an X-ray. However, everyone is exposed to sources of natural radiation throughout their life.

Natural radiation is sometimes known as background radiation. Sources of background radiation include:

• radon – a naturally occurring radioactive gas found in low levels in the atmosphere 
• cosmic rays – a type of radiation that originates from space (from the sun and stars)
• the earth – soil and rocks contain various radioactive materials that have been present since the earth was formed; these contribute to our exposure, as do building materials made from soil, rocks and stones
• food and water – for example, nuts, bananas, red meat and potatoes all contain tiny traces of radiation

Read more about radiation.

Cancer risk

Being exposed to X-rays carries a theoretical risk of triggering cancer at a later date, as does exposure to background radiation.

However, this risk is very low. For example, the Health Protection Agency (HPA) has calculated that:

• an X-ray of your chest, teeth, arms or feet is the equivalent of a few days' worth of background radiation, and has a less than 1 in 1,000,000 chance of causing cancer
• an X-ray of your skull or neck is the equivalent of a few weeks' worth of background radiation, and has a 1 in 100,000-1,000,000 chance of causing cancer
• an X-ray of your breasts (mammogram), hip, spine, abdomen or pelvis is the equivalent of a few months' to a year's worth of background radiation, and has a 1 in 10,000-100,000 chance of causing cancer
• an X-ray that uses a contrast fluid, such as a barium meal, is the equivalent of a few years' worth of background radiation, and has a 1 in 1,000-10,000 chance of causing cancer

It's important to put the risk of developing cancer from X-rays into perspective. More than one in three people in the UK will develop some form of cancer during their lifetime.

Your risk of developing cancer depends on many factors, including your age, lifestyle and genetic make-up.

You can read more about your lifetime risk of developing cancer on the Cancer Research UK website.

X-rays and pregnancy

The doses of radiation used during an X-ray aren't thought to pose a risk to an unborn baby. However, as a precaution, X-rays that directly target the womb (abdominal X-rays) aren't usually recommended unless there's a clear clinical need.

In some cases, an alternative method that doesn't involve radiation, such as an ultrasound scan, may be recommended.

Before having an X-ray, you may be asked about the date of your last period. This is to check whether there's a chance that you could be pregnant.

Don't panic if you have an X-ray and later discover that you're pregnant. Even the most powerful types of X-rays, such as a barium enema, aren't thought to have any adverse effects on the outcome of a pregnancy.