X-ray
Published by Bupa's health information team, July 2009.
This factsheet is for people who are considering having an X-ray, or who would like information about it. Your care will be adapted to meet your individual needs and may differ from what is described here.
- About X-ray tests
- What are the alternatives?
- Preparing for your X-ray test
- What to expect at the hospital
- About the procedure
- What to expect afterwards
- What are the risks?
- If you are pregnant
- Questions and answers
- Related topics
- Further information
- Sources
About X-ray tests
An X-ray test (radiograph) is a quick and painless way for doctors to diagnose and monitor many health conditions.
X-rays are a form of radiation. Unlike light radiation (normal light), which is absorbed or reflected by the skin, X-ray radiation passes in straight lines through the body. An X-ray machine works by projecting a beam of X-rays through part of your body. An X-ray sensitive detector, similar to a camera film, captures what comes out the other side as a black and white image called a radiograph - an X-ray image.
Structures inside the body that are dense, such as bones, absorb X-rays. This weakens the X-ray beam, so that the bone casts a 'shadow'. This comes out white on the final image. Less dense structures, like the air in the lungs, let X-rays pass through them almost completely. There is no shadow and this part of the image will be black. Because parts of the body vary in how dense they are and block X-rays by different amounts, they show up as shades of grey, from black to white.
The images captured by the X-ray machine are now usually stored digitally and displayed on a computer screen. The image may also be printed or copied onto a compact disc. In smaller hospitals or dental surgeries, you may still come across X-rays processed on film, which is viewed by shining light from behind.
X-rays can be used to look at bones, joints and soft tissues, for example, to look for fractures after a fall or injury. An X-ray image of the chest shows the size and shape of the heart and is good for spotting signs of infection in the lungs. An abdominal X-ray image shows up the outline of the bowel, and can pick up kidney stones in the tubes connecting the kidneys and bladder.
What are the alternatives?
There are limits to what an X-ray image can show. X-rays aren't generally very helpful in giving information about solid organs, such as the liver or kidneys, which are made up of tissues of very similar density. Similarly, the nerves and brain don't show up very well on X-ray images.
Alternative imaging procedures include ultrasound, magnetic resonance imaging (MRI) and a special form of X-rays called computerised tomography (CT). Your doctor will discuss with you which test is most suitable.
Preparing for your X-ray test
You don't usually need to make any preparations before your test.
What to expect at the hospital
The examination is routinely done as an out-patient procedure in the radiology or imaging department.
Your radiographer will explain the procedure and ensure that you're happy to go ahead with the X-ray test. Radiographers are specially trained in imaging techniques and do most of the work in taking X-ray images. The images will then be sent to a radiologist (a doctor who specialises in using imaging methods to diagnose medical conditions).
About the procedure
The test usually takes only a few minutes but will vary depending on what part of your body is being examined. Most of this time is spent getting into position and preparing the equipment.
In a private cubicle, you will usually be asked to remove your clothing and put on a hospital gown. You will be taken to the X-ray room where you will be positioned against the part of the machine containing the recording plate. Alternatively, you may be asked to lie down on an X-ray table or sit in a chair at the side of the table.
For a chest X-ray image, you will be asked to stand with your chest up against the plate and hold on to handles either side of your body. The radiographer will bring into place the projector part of the machine. This produces the X-ray beam so that the X-rays shine from back to front through your chest.
Your radiographer will operate the X-ray machine from behind a screen, but will be able to see and hear you at all times.
You will be asked to stay still and, particularly for a chest X-ray image, sometimes to take a deep breath and hold it for a few seconds. The X-ray beam is produced for only a fraction of a second.
The machine might make a slight whirring noise. Your radiographer may need to take further X-ray images at different exposures or in different positions. If you're having an X-ray image taken of your arm or leg, you will probably have two views done, one front to back through the limb and one side to side.
What to expect afterwards
When you feel ready, you will be able to go home. You can drive if you wish.
A report will be sent to the doctor who requested your test. This can take several days to reach your doctor. Before you go home, please ask your radiographer when you can expect to get your results.
What are the risks?
X-rays are commonly used and generally safe.
You will be exposed to some X-ray radiation but the amount you receive isn't considered to be harmful. The level of exposure is about the same as you would receive naturally from the environment over three days to seven months depending on the part of the body being examined.
The staff who carry out the procedure, the equipment they use and the hospital itself are all regulated by legislation. Regular monitoring ensures that using X-rays for diagnosis is as safe as possible.
If you are pregnant
Although the radiation dose being used is generally thought to be safe for adults, it may harm an unborn baby. Therefore, X-rays aren't usually used on pregnant women unless there is an urgent medical reason.
If you could be pregnant, please tell your doctor before the day of your appointment. Your doctor will explain the benefits and risks of X-rays and will also discuss alternatives to the procedure.
Related topics
Further information
- The Royal College of Radiologists
020 7636 4432
www.rcr.ac.uk
Sources
- Diagnostic radiology leaflets. The Royal College of Radiologists. www.rcr.ac.uk, accessed 5 February 2009
- Welcome to the virtual departments. The Royal College of Radiologists. www.goingfora.com, accessed 5 February 2009
- X-rays: how safe are they? Health Protection Agency. www.hpa.org.uk, accessed 5 February 2009
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Publication date: July 2009
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