An X-ray is a quick and painless procedure commonly used to produce images of the inside of the body.

It's a very effective way of looking at the bones and can be used to help detect a range of conditions.

X-rays are carried out by trained specialists called radiographers.

How X-rays work

X-rays are a type of radiation that can pass through the body. They can't be seen by the naked eye and you can't feel them.

As they pass through the body, the energy from X-rays is absorbed at different rates by different parts of the body. A detector on the other side of the body picks up the X-rays after they've passed through and turns them into an image.

Dense parts of your body that X-rays find it more difficult to pass through, such as bone, show up as clear white areas on the image. Softer parts that X-rays can pass through more easily, such as your heart and lungs, show up as darker areas.

An ultrasound scan, sometimes called a sonogram, is a procedure that uses high-frequency sound waves to create an image of part of the inside of the body.

An ultrasound scan can be used to diagnose a condition, or guide a surgeon during certain procedures.

How ultrasound scans work

Preparing for an ultrasound scan

Before having some types of ultrasound scan, you may be asked to follow certain instructions to help improve the quality of the images produced.

Depending on the area of your body being examined, the hospital may ask you to remove some clothing and wear a hospital gown.

There are no known risks from the sound waves used in an ultrasound scan. Unlike some other scans, such as CT scans, ultrasound scans don't involve exposure to radiation.

Are there any risks?

External and internal ultrasound scans don't have any side effects and are generally painless, although you may experience some discomfort as the probe is pressed over your skin.

A computerised tomography (CT) scan uses X-rays and a computer to create detailed images of the inside of the body.  

CT scans are sometimes referred to as CAT scans or computed tomography scans.

They're carried out in hospital by specially trained operators called radiographers, and can be done while you're staying in hospital or during a short visit.

When CT scans are used

CT scans can produce detailed images of many structures inside the body, including the internal organs, blood vessels and bones.

They can be used to:

• diagnose conditions – including damage to bones, injuries to internal organs, problems with blood flow, stroke, and cancer
• guide further tests or treatments – for example, CT scans can help determine the location, size and shape of a tumour before having radiotherapy, or allow a doctor to take a needle biopsy (where a small tissue sample is removed using a needle) or drain an abscess
• monitor conditions – including checking the size of tumours during and after cancer treatment

Preparing for a CT scan

Your appointment letter will mention anything you need to do to prepare for your scan.

You may be advised to avoid eating anything for several hours before your appointment to help make sure clear images are taken.

Safety of CT scans

CT scans are quick, painless and generally safe. The amount of radiation you're exposed to during a CT scan varies, depending on how much of your body is scanned.

CT scanners are designed to make sure you're not exposed to unnecessarily high levels.

Generally, the amount of radiation you're exposed to during each scan is equivalent to between a few months and a few years of exposure to natural radiation from the environment.

It's thought exposure to radiation during CT scans could slightly increase your chances of developing cancer many years later, although this risk is thought to be very small (less than 1 in 2,000).

For more information, read GOV.UK: patient dose information.

The benefits and risks of having a CT scan will always be weighed up before it's recommended.

Talk to your doctor or radiographer about the potential risks beforehand if you have any concerns.

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