The discovery of X-rays, which are now commonly used in medicine and veterinary medicine, was made by the physicistWilhelm Conrad Röntgen in 1895. No details of the specifics of this discovery are currently available, as Röntgen clearly expressed in his will that all his scientific material should be destroyed after his death.

However, it seems that the discovery of X-rays was almost accidental, when Röntgen recognised the shadow of his own hand through the beam. Since then, the physicist proceeded with a series of experiments that would bring about a real revolution in modern medicine, and which came to the attention of the world with the famous image of his wife’s hand.

At the time, Röntgen did not yet understand which rays could define these images, which is why he called them X-rays – the name still used to identify them today.

The X-ray emission process

It is easy to see that the X-ray emission technique initially used by Röntgen is in no way comparable to the current one. The emission systems and generators of the time were very different, and over time, they have been implemented to ensure absolute safety for both the examiner and the X-ray recipient.

X-rays are emitted by a process in which electrons are accelerated by means of a very high voltage and directed against a plate usually made of tungsten and molybdenum. The contact of the electrons with the plate generates the X-rays.


High voltage is generated with the aid of current generators connected to two different types of equipment: monoblocks or tubes. What are the main differences between the two?

The monoblock is a compact system, which is especially preferred in portable units or ward units. One of its key features is that it does not require high-voltage cables or large generators, which in practice results in a more limited X-ray emission than that provided by X-ray tubes.

The monoblock consists of a casing, usually made of aluminium, inside which is housed the X-ray tube immersed in diathermic oil (i.e. characterised by a high boiling temperature of approximately 400/500°C at atmospheric pressure). The diathermic oil ensures the cooling of the tube, which produces a large amount of thermal energy – i.e. heat .when stressed by the high voltage.

As far as the tubes that can be inserted into a monoblock , are concerned, they can have very different characteristics. A distinction is usually made between rotating and fixed tubes. The former has rotating anodes and consist of a plate which rotates at very high speed. This will result in the electrons being able to hit different areas of the plate as it rotates. Consequently, the surface of the plate will be subject toslower wear than that of a fixed anode tube.

Where X-rays are used: fixed, mobile and portable units

In which units are X-rays normally used?

The main distinction here is betweenfixed, mobile and portable units..

  • Fixed units are conventional bone rooms for human medicine, consisting of a patient table, a column on which the X-ray source is installed and a wall-mounted teleradiograph for live examinations.
  • On the other hand, mobile units, also called mobile ward units, are systems on wheels that can be easily transported within the different departments of a hospital. This type of solution allows examinations to be performed without the need for the bedridden patient to be moved around the radiology department and is therefore particularly useful for patients who cannot be moved.
  • Finally, portable units are very compact systems that weigh between 6 and 15 kilograms. These are X-ray generators which, by their nature, obviously cannot reach the emission levels typical of portable units or conventional bone rooms but are ideal where it is not possible to operate with a different unit. A typical example is sports events./li>
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