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X-Ray Roentgen took of his wife Berta in 1895

Intra-operative x-ray showing implants

About X-rays (aka roentgenographs)

X-rays are used to investigate many medical problems. It is a quick and painless investigation. For many years it was the only investigation which gave a picture from organs inside the body of a living person. Despite modern imaging techniques like ultrasound, MRI and CT (which uses x-rays) it remains an important investigation including spinal conditions.

X-rays were discovered in 1895 by the German physicist Wilhelm Konrad Roentgen who won the first Nobel price for physics in 1901. It revolutionised not only medical diagnostics but also the discovery and use of radioactivity. In some parts of the world, x-rays are called roentgenographs.

How it works

X-rays are generated by an X-ray tube, which uses a high voltage to accelerate electrons to a high speed (velocity). The high velocity electrons collide with a metal target creating the X-rays. These x-rays are send through the body and are detected again with a camera or special x-ray film when they leave the body. Some tissues, in particular bone, absorb x-rays which produces a shadow in the camera. This gives the x-ray picture.

What it shows

The main role in the spine is detecting problems with the bony structure like collapse of the vertebral body, fractures and changes of wear and tear. X-rays can also show abnormal tissue swelling in infections. Indirectly, they can show wear and tear of the intervertebral discs as the gap between the bones becomes narrower. Some x-rays are taken when the spine (neck or lower back) are bend forward and backwards (flexion and extension views). This can show instability due ligament damage.

What it does not show

Any neural structures (nerves and spinal cord), blood vessels or intervertebral discs cannot be seen. Therefore they cannot show a trapped nerve or slipped disc! This means that they have no role in investigating conditions like sciatica unless there are very specific indications.

X-rays in flexion and extension showing instability (yellow arrow)

When it should be done

Indications for plain x-rays include fractures, vertebral body collapse due to osteoporosis or tumours, severe scoliosis, spondylolisthesis and suspected instability of the spine (i.e. in rheumatological disorders).

When it should not be done

The role of x-rays in investigating back pain is very limited unless any of the above condition is suspected.

Pregnancy: x-rays can harm the baby but special precautions can be taken to minimise the risk if the x-ray is important. However, it is best avoided.

It should not be done for simple neck or low back pain or to investigate sciatica or nerve entrapment (MRI).

Commonly asked questions

Can x-rays be dangerous for my health?

In principle, x-rays can damage various tissues of the body but reasonably large doses are required. some spinal x-rays, in particular in the lumbar spine require higher doses than for example a chest x-ray. However, even several x-rays in a short time will not cause any harm. Still, a patient should only have an x-ray if there is a clear indication.

How many x-rays can I have?

This depends on the type of x-rays. For further information click here. This will take you to a different NHS patient information website.

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