History / general information

X-ray examination is one of the best-known diagnostic methods in medicine. Wilhelm Conrad Röntgen discovered the radiation named after him (in German, X-rays are called Röntgenstrahlen) in 1895 during his research on cathode rays. In 1901 he received the Nobel Prize in Physics. Hardly any discovery has influenced medicine as lastingly as the discovery of X-rays. X-rays are electromagnetic waves that can blacken X-ray film. When X-rays pass through a material or a body, they are weakened to different degrees. The intensity of the radiation that then reaches the X-ray film produces different degrees of blackening, from which the X-ray image is created. How much the radiation is weakened depends on the type of material or tissue. Soft tissue such as muscle or fat is penetrated more easily than hard tissue such as bone. This is why bone looks almost white on an X-ray and soft tissue looks dark. Unlike an X-ray image, fluoroscopy is a moving image, similar to a film camera compared with a photo camera. The radiation intensity in fluoroscopy is therefore much higher than for a single image, because the “exposure time” is much longer.

Soon after X-rays were discovered, however, it became clear that their many unexpected benefits for diagnosis and treatment came with considerable side effects. X-rays carry much more energy than visible light. The unwanted effects of X-rays are therefore mainly due to possible damage to body cells and in particular to human genetic material, DNA. Damage to the DNA of germ cells can cause hereditary diseases, and damage to body cells can cause cancer. Different body cells differ in their sensitivity to radiation. The blood-forming bone marrow or the female breast, for example, are very sensitive, while bone, skin and muscle are relatively insensitive.

An exact assessment of the danger of X-rays is hardly possible. Statements about the risk of an X-ray examination are therefore usually based on statistical calculations and express probabilities. Technical developments such as better X-ray film, shorter exposure times, film collimators, lower radiation doses, stricter indications for examinations, radiation protection regulations and quality assurance measures have continuously reduced the risk from X-rays. As a result, only relatively low radiation doses are used in medicine today. We should not forget that we are constantly exposed to natural radioactive radiation. It consists of cosmic radiation, terrestrial radiation and the intake of radioactive substances (think, for example, of the increased radioactivity in mushrooms since the Chernobyl nuclear accident). The radiation dose of a chest X-ray is roughly equivalent to the dose of a return flight to Mallorca. The radiation exposure of a bone density measurement (DEXA) is comparable to spending 30 minutes on the Zugspitze, Germany’s highest mountain.

Indications

Chest X-ray

A common X-ray examination is the chest X-ray. It gives the doctor information about the structure of the lungs and the size and shape of the heart. It can detect pneumonia, tuberculosis, lung cancer or lung metastases. Heart failure, fluid around the heart, rib fractures or rarer diseases such as pulmonary sarcoidosis and other autoimmune diseases can also be detected.

X-ray for degenerative changes

X-ray examination of the skeleton is essential for diagnosing rheumatic diseases or orthopaedic disorders and malformations, and for assessing the extent of degenerative disorders such as osteoarthritis or spinal damage.

X-ray for rheumatic changes

X-rays are indicated in rheumatic diseases, e.g. rheumatoid arthritis, for several reasons. On the one hand, they are an important part of confirming the diagnosis; on the other hand, follow-up X-rays at fixed intervals are essential to document arthritic changes and assess how well basic therapies are working.

X-ray after accidents

A very common reason for an X-ray is to rule out or detect bone fractures and ligament injuries, but bone tumours or skeletal metastases can also be detected. X-rays often give signs of osteoporosis, which can then be confirmed and quantified by a bone density measurement (DEXA).

Radiation exposure

As mentioned above, the radiation doses used in medical diagnostics today are very low. Nevertheless, X-ray examinations may only be carried out when there is a proper indication, and the doctor must carefully weigh up risks and benefits. We also recommend having an X-ray record card to avoid duplicate examinations and to give you an overview of the X-rays you have had. We will gladly issue you an X-ray record card if you do not have one yet.