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X-ray is an imaging technique that has been used since 1895 to show up abnormalities in bones and certain body tissue, such as breast tissue.
X-rays are a type of high-energy radiation that is like light waves but higher in energy. An x-ray machine can produce short bursts of x-rays that pass easily through fluids and soft tissues of the body but are blocked by dense tissue such as bone.
Contrast x-rays use a substance (called a contrast medium) that makes hollow or fluid-filled structures visible. This means that structures such as the digestive tract, blood vessels or urinary system that do not usually show up on x-ray, can be seen. The substance is injected or swallowed and X-rays cannot pass through it, so the area will appear white on the x-ray.
Why is it necessary?
X-rays are necessary to show images of abnormalities that cannot be seen from outside the body, such as broken bones (fractures) or shadows on the lungs.
How is it performed?
You will be asked to lie on a table or stand against a surface so that the part of your body being x-rayed is between the x-ray source and a drawer containing a film cassette (similar to a photographic film).
The designated part of your body is exposed to x-rays for a fraction of a second. The x-rays hit the film, which is then developed. The developed film is studied by a radiologist and sent to your doctor.
You have to keep still so the image is clear and not blurry. The x-ray is painless and you cannot see or feel it.
More than one x-ray may be taken from different angles to give more information. For example, when examining the lungs, both the front and side of the body will be x-rayed.
How does it work?
X-rays are a form of radiation similar to light waves but with a higher energy, that enables them to pass through body tissue.
The parts that allow x-rays through (such as air in the lungs) show up black on the film. A collection of fluid in the stomach or lung will show up as grey or ‘a shadow’. Soft tissue such as muscle and body organs show up as various shades of grey and dense parts of the body such as bone show up white.
The doctor will show you your x-ray and point out any abnormalities such as a bone fracture or shadow on the lung.
What is it used for?
X-rays produce clear images of bone and are used to check for fractures. They are also used for teeth and joints. Chest x-rays are used to examine the heart and lungs for heart conditions or tumours in the lung. Bones can be examined using a low dose of x-ray to look for changes in the density of the tissue that may indicate a condition such as osteoporosis. Breast tissue can also be examined using a low dose of x-ray to look for tumours; this is called a mammogram.
Often, an x-ray is all that is needed to diagnose or assess the presenting symptoms. In some cases, more sophisticated imaging techniques may be needed for accurate or further assessment.R
There is little risk to health from one x-ray, but with repeated tests there is a risk that the radiation may damage body cells, possibly leading to cancer in the future. There is only a risk if you have a high number of x-rays; one every other year is not harmful.
If an x-ray is justified necessary, the dose of radiation is always kept as low as possible and the reproductive organs are shielded. Radiographers wear a lead apron or go behind a protective screen to avoid repeated exposure to x-rays. The earlier in life you are exposed to radiation, the greater the risk.
Women who are, or are likely to be pregnant, should not have an x-ray, especially in the first three months when the foetus is growing rapidly. There is a small risk of causing harm to the unborn baby, depending on the type of x-ray, the level of dosage and the part of the body being x-rayed (i.e. pelvis or abdomen).
You will be asked for the date of your last period before you have an x-ray; this is to check that there is no chance you could be pregnant. If possible, you should postpone the x-ray until after your baby is born. But if you do have an x-ray and later discover you are pregnant, the risks are not high enough to have to terminate the pregnancy (1).
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