Expert reviewer, Dr Daniel Boxer, Consultant Radiologist
Next review due August 2019

X-rays are a form of radiation. An X-ray machine works by projecting a beam of X-rays through the part of your body that your doctor needs to look at. An X-ray sensitive detector then captures the radiation that comes out on the other side of your body in the form of a black and white image. This is called a radiograph.

X-rays are absorbed differently by different structures, tissues and organs in your body. Dense (very solid) structures, such as your bones, absorb X-rays and appear as light grey on the radiograph. Less dense structures, like the air in your lungs, let X-rays pass through them and show up as dark grey or black.

Nowadays, the images captured by an X-ray machine are usually stored digitally and displayed on a computer screen.

Surgeons looking at a hand X-ray

What are X-rays used for

X-rays use radiation to produce images of the inside of your body. They’re carried out by radiographers (health professionals trained to perform imaging techniques). Doctors use X-rays to help diagnose and monitor many different health conditions, including problems with your lungs, bowel or heart. An X-ray image of your chest may show whether you have an infection in your lungs. X-rays are also commonly used to look for fractures in your bones after a fall or injury, as well as other joint problems such as arthritis.

Preparing for an X-ray

You usually have an X-ray as an out-patient procedure in the radiology or imaging department of a hospital, health clinic or dental practice.

Depending on which part of your body is being X-rayed, you may wish to wear clothing that’s easy to remove.

Your radiographer will discuss with you what will happen before, during and after an X-ray. If you’re unsure about anything, don’t be afraid to ask. No question is too small. It’s important that you feel fully informed so you’re happy to go ahead with the X-ray.

What are the alternatives to an X-ray?

Sometimes a different type of imaging test may be more appropriate for you. This usually depends on which part of your body needs to be looked at. Alternative tests include an ultrasound scan, a magnetic resonance imaging (MRI) scan or a computerised tomography (CT) scan. Your doctor will discuss with you which test is most suitable.

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What happens during an X-ray?

X-rays usually take only a few minutes.

You may be asked to remove your clothing, put on a hospital gown and take off your jewellery before an X-ray. This will depend on the area of your body that’s being exposed to the radiation. You’ll usually be taken to a private cubicle so that you can change.

Your radiographer will help you to get into the right position on the X-ray machine. Or you may be asked to lie down on an X-ray table or sit in a chair beside the table. It may take a few minutes to get you into the right position. During the X-ray you’ll need to keep still. Sometimes, especially if you’re having a chest X-ray, you’ll need to take a deep breath and hold it for a few seconds.

Your radiographer will stand behind a screen to use the X-ray machine. But they’ll be able to see and hear you at all times. They may need to take more than one X-ray, or X-rays at different angles. You may have to get into a number of slightly different positions for this.

The images will then be sent to a radiologist (a doctor who specialises in using imaging methods to diagnose medical conditions).

What to expect afterwards

You’ll usually be able to go home when you feel ready.

Your doctor will usually receive a report from the radiologist. They may also receive your X-ray images. This can take several days. Before you go home, ask your radiographer when you can expect to get your results.

If you’re seeing a radiologist, they may be able to view your images on a computer screen immediately after your X-ray.

You may be able to ask for a copy of your images on a disc or have them sent to another hospital electronically. This is particularly useful if you’re seeing a doctor in a different hospital, or if you’ll be travelling abroad.

What are the risks?

As with every test, X-rays have some risks. The benefits of having an X-ray usually outweigh these risks.

When you have an X-ray, you’ll be exposed to some radiation. But radiographers are trained to keep your exposure to a minimum, and the amount of radiation you receive during an X-ray isn't considered to be harmful. You're exposed to natural background radiation in the atmosphere all the time. The amount of radiation you're exposed to during a chest X-ray is the same as around three days of this background radiation.

Different radiology tests expose you to different doses of radiation. The amount of radiation you receive from a plain X-ray is lower than other types of radiology tests, such as a CT scan.

Having several X-rays may slightly increase your chance of getting cancer many years later. But the benefits of having an X-ray usually outweigh this very small risk. If you’ve had any X-rays or scans recently, let your doctor know – you may not need more tests.

The radiation from an X-ray is generally thought to be safe for adults, but children are more sensitive to its damaging effects. Their doctor will only refer them for an X-ray if it’s entirely necessary. If your child has an X-ray, it’s likely that you’ll be able to go into the X-ray room with them. You’ll be given a lead apron to wear to protect your body from unnecessary radiation.

If you’re pregnant, an X-ray may harm your unborn baby. You won’t be given an X-ray unless there’s an urgent medical reason. If you think you could be pregnant, tell your doctor before your appointment. Your doctor will advise you whether or not to go ahead with the X-ray.

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Related information

    • Conventional radiography. The MSD Manuals., last full review/revision January 2015
    • X-rays. Cancer Research UK., updated April 2015
    • Radiology. Oxford Handbook of Clinical Medicine (online). 9th ed. Oxford Medicine Online., published online January 2014
    • Chest x-ray – systematic approach. PatientPlus., last checked April 2016
    • Plain skull x-ray. PatientPlus., last checked February 2014
    • Risks of medical radiation. The MSD Manuals., last full review/revision January 2015
    • Medical radiation: uses, doses, measurements and safety advice. Public Health England., last updated January 2016
    • Cancer statistics for the UK. Cancer Research UK., accessed May 2016
    • Personal communication, Daniel Boxer, Consultant Radiologist, July 2016
    • Rheumatoid Arthritis. PatientPlus., last checked January 2015
    • Paediatric X-ray imaging. Food and Drug Administration (FDA)., last updated April 2016
  • Reviewed by Laura Blanks, Specialist Health Editor, Bupa Health Content Team, August 2016
    Expert reviewer, Dr Daniel Boxer, Consultant Radiologist
    Next review due August 2019

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