X-rays are also called röntgen rays, from the name of the German physicist Konrad Wilhelm Röntgen who discovered them in 1895, demonstrating their existence through a radiogram of his wife's hand.
X-rays, passing through matter, produce ions, therefore they are called ionizing radiation. These radiations dissociate the molecules and, if these belong to cells of living organisms, they produce cellular lesions. Because of this property, X-rays are used in the therapy of some types of tumors. They are also used in medical diagnostics to obtain radiographs, ie "photographs" of the internal organs, made possible by the fact that the different tissues are opaque to X-rays, ie they absorb them more or less intensely depending on their composition. Therefore, when they pass through matter, the X-rays undergo an attenuation which is greater the higher the thickness and specific weight of the material passed through, both dependent on the atomic number (Z) of the material itself.
In general, a radiation is made up of quanta of electromagnetic waves (photons), or of particles with mass (corpuscular radiation). A radiation, made up of photons or corpuscles, is said to be ionizing when it causes the formation of ions along its path.
X-rays are made up of electromagnetic radiation, which in turn are of different types: radio waves, microwaves, infrared, visible light, ultraviolet light, X-rays and gamma rays. The path of the radiations essentially depends on their interaction with the matter encountered during the journey. The more energy they have, the faster they move. If they hit an object, the energy is transferred to the object itself.
Therefore, when passing through matter, the ionizing radiations release all or part of their energy, producing ions which, in turn, if they acquire sufficient energy, produce further ions: thus a swarm of ions develops on the trajectory of the incident radiation which proceeds up to " exhaustion of the initial energy. Typical examples of ionizing radiation are X-rays and γ rays, while corpuscular radiation can be made up of different particles: negative electrons (βˉ radiation), positive electrons or positrons (β + radiation), protons, neutrons, atom nuclei of helium (α radiation).
X-rays and medicine
X-rays are used in diagnostics (radiographs), while other radiations are also used in therapy (radiotherapy). These radiations occur naturally or are artificially produced by radiogenic devices and particle accelerators. The energy of the X-rays is between about 100 eV (electron volts) for radiodiagnostics and 108 eV for radiotherapy.
X-rays have the ability to penetrate through biological tissues opaque to light radiation, resulting only partially absorbed. So for radiopacity of the material medium means the ability to absorb photons X and for radiolucency we mean the ability to let them pass. The number of photons that can cross the thickness of a subject depends on the energy of the photons themselves, on the atomic number and on the density of the media that compose it. Therefore, the resulting image is a map of the differences in attenuation of the beam. incident photons, which in turn depends on the inhomogeneous structure, therefore on the radiopacity of the body section examined. The radiopacities, therefore, are different between a limb, the soft tissues, and a bone segment. They also differ in the chest, between the pulmonary fields (full of air) and the mediastinum. There are also causes of pathological variation of the normal radiopacity of a tissue; for example, the increase of the same in the case of a lung mass, or the its decrease in bone in the event of a fracture.
Other articles on "Radiography and X-rays"
- Radiology and radioscopy
- X-ray
