What are X-rays?

X-rays are a type of high-energy radiation that is used for body imaging. An X-ray machine can produce short bursts of X-rays. The rays pass easily through fluids and soft tissues of the body. However, dense tissue such as bone will block some of the X-rays. The denser the tissue, the less X-rays pass through it and hence we are able to get an image.

How is an X-ray test done?

A film, similar to a photographic film, is placed behind the part of the body being X-rayed. The X-ray machine fires a short burst of X-rays through part of your body. The X-rays hit the film and gives an image. The more X-rays that hit the film, the blacker it develop. So, dense parts of the body that block many of the X-rays show up as white (such as bones). Hollow or air-filled parts of the body show up as black (such as parts of the lung). Soft tissues (such as muscle and body organs) show up as various shades of grey, depending on how dense they are. The film is then studied by an X-ray doctor (radiologist) who makes a report for the doctor who requested the test. An ordinary X-ray test is painless. You cannot see or feel X-rays. You should stay still when the X-ray beam is ‘fired’, as otherwise the picture may be blurred.

What can ordinary X-rays show?

  • Bones, teeth, bone fractures, and other abnormalities of bone.
  • Joint spaces and some abnormalities of joints, such as osteoarthritis.
  • The size and shape of the heart. So, certain heart conditions can be detected.
  • Changes in the density of some softer tissues. For example, a lung tumor is denser than air-filled lung and will show as a ‘shadow’ on a chest X-ray. A breast tumor is denser than ordinary breast tissue and shows as a ‘shadow’ on an X-ray of the breast.
  • Collections of fluid – for example, in the lung or gut – may show as grey ‘shadows’ against the normal black of the air-filled chest, or hollow gut.

An ordinary X-ray is a quick, easy and a relatively cheap test. It may be all that is needed to diagnose or assess various problems. However, an ordinary X-ray has limited use. More sophisticated ‘contrast’ X-rays, CT scans, or other imaging techniques may be needed for accurate or further assessment of certain body parts, particularly of soft tissues and organs such as the brain or liver.

Are there any risks from X-rays?

There is very little risk with having one X-ray test. However, with repeated tests there is a risk that the X-rays may damage some cells in the body, possibly leading to cancer in the future. The dose of X-ray radiation is always kept to the minimum needed to get a good picture of the particular body part being checked.Pregnant women, if possible, should not have an X-ray test, as there is a small risk that X-rays may cause an abnormality to the unborn child. This is why women are asked before having an X-ray if they are, or might be, pregnant.