X-ray

Examining bones

As bone is made out of calcium, which is a very hard and tough material, it shows up very clearly on X-rays. This makes X-rays very useful in diagnosing many different conditions and other problems related to bones, such as:

  • fractures and breaks
  • problems with your teeth, such as tooth decay
  • osteoporosis (thinning and weakening of your bones)
  • osteomyelitis (a bone infection)
  • scoliosis (abnormal curvature of the spine)
  • cancers of the bone, such as osteosarcoma and Ewing's sarcoma.
  • arthropathy (e.g. osteoarthritis, rheumatoid arthritis)

Examining soft tissue

Although major organs and blood vessels do not show up as clearly on X-rays as bones, they are visible. Therefore, chest X-rays are a good way of looking for changes or abnormalities in your heart, lungs and major arteries.

In particular, chest X-rays can be used to help diagnose:

  • lung conditions, such as pneumonia, lung cancer and chronic obstructive pulmonary disease (COPD), and
  • heart conditions, such as heart failure, congenital heart disease and pericarditis (inflammation of the lining of the heart).

Abdominal x-rays are also useful as they can demonstrate other soft tissue structures and pathologies such as kidney stones and abnormal bowel gas patterns

X-rays and contrast fluids

X-rays are often used in combination with contrast fluids to produce a more detailed picture of certain organs and blood vessels.

Most contrast fluids are 'radio-opaque', which means they block the passageway of X-rays. When a contrast fluid coats the lining of organs and blood vessels, they show up clearly in white. Barium is a widely used contrast fluid.

The different ways that X-rays can be used in combination with contrast fluids are described below.

Barium swallow

A barium swallow is a procedure where you are given some barium solution to drink. Once the barium moves down into your upper digestive system, a series of X-rays is taken. The test is often used to diagnose problems with your upper digestive system, such as problems swallowing (dysphagia), or persistent symptoms of abdominal pain.

Barium enema

barium enema involves having barium solution pumped through your anus (back passage) into your bowel. Barium enemas are used to diagnose bowel problems, such as persistent constipation and blood in your faeces (stools).

Angiogram

An angiogram is a detailed way of looking inside blood vessels to check for problems, such as blocked or narrowed vessels or weakness in the walls of a blood vessel (aneurysm). A small tube, called a catheter, is inserted into your groin and guided to the site of the vessel using X-ray.

Contrast fluid is then pumped through the catheter and a series of X-rays is taken to show how the fluid moves through the blood vessel. Studying the movement of the fluid through a blood vessel can often highlight problems, such as a blockage.

Intravenous urogram (IVU)

An intravenous urogram (IVU) is where a contrast fluid (usually an iodine solution) is injected into your veins, before it moves into your kidneys and bladder. X-rays are then taken of your kidneys and bladder. The procedure is often used to diagnose problems with your urinary system.

Glossary

Dose
Dose is a measured quantity of a medicine to be taken at any one time.
Heart
The heart is a muscular organ that pumps blood around the body.
Joint
Joints are the connection point between two bones that allow movement.
Lung
Lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen.
Tissue
Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.
X-ray
An X-ray is a painless way of producing pictures of inside the body using radiation.

Photon absorption

X-rays are similar to visible light, in that they are both waves of energy that are made up of tiny particles (photons). The difference is that the photons in X-rays have a higher energy level than those found in light (in other words, X-rays have a higher frequency and a lower wavelength than light).

Unlike light, which is absorbed by your skin, most of the photons in X-rays pass through your body due to their higher energy level. As they pass through your body, the photons are absorbed at different rates. This pattern of absorption shows up on the X-ray images. An X-ray image is produced in a similar way to how a shadow is cast, but X-rays are used rather than visible light.

Parts of your body that are made up of thick and dense material, such as your bones, absorb lots of photons, so show up as clear white areas on the X-rays. Other parts that are made of softer material, such as your lungs and heart, absorb only a small amount of photons, so show up as darker patches on the X-ray image.

The X-ray machine

An X-ray machine consists of:

  • an X-ray tube,
  • lead shielding, and
  • a photographic plate.

The X-ray tube is like a giant light bulb that uses high-voltage electricity to generate the X-rays. The lead shielding is used to direct the X-rays towards a specific part of your body while preventing them from escaping in all directions. The photographic plate captures the image of the X-rays as they pass through your body.

In the past, the photographic plate used the same type of film as traditional cameras. Nowadays, the photographic plate in most X-ray machines is directly connected to a computer so that a digital image can be taken.

The X-ray Room

The x-ray room will consist of a table, a wall stand and the x-ray tube which is suspended directly from the ceiling. The radiographer will position you either lying on the table or standing at the wall stand, depending on what x-ray you require. The tabletop may move as the radiographer puts you into the correct position.

The radiographer will then stand at a computer console behind a glass screen whilst the x-ray is being taken. You may be asked to follow some simple breathing instructions during your x-ray. This is to help produce the most diagnostic image possible

 

Glossary

Lung
Lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen.
Stomach
The sac-like organ of the digestive system. It helps digest food by churning it and mixing it with acids to break it down into smaller pieces.
Tissue
Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.
X-ray
An X-ray is a painless way of producing pictures of inside the body using radiation. 

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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