Starting with A for "ACE inhibitor" and continuing through to Y for "Yolk Sac Tumour", we give you succinct explanations for scientific and medical terms in clear and simple words.
- X-raysHigh energy electromagnetic photon radiation, discovered by Wilhelm Conrad Röntgen in 1895, also known as Röntgen rays.
1. Röntgen braking radiation ("Bremsstrahlung"): this arises as a result of the deceleration of high energy electrons in the electric field of atomic nuclei. In the Röntgen tube this process occurs, for example, in the tungsten in the anode. The resulting X-rays have a continuous spectrum, which can be modified by filtering, which can remove the lower energies; 2. Characteristic X-rays: these are emitted when an electron in the electron cloud with an intermediate or high primary quantum number jumps into an empty orbital of lower energy. This orbital must have been previously emptied by a suitable method, such as photoeffect, electron capture or electron bombardment. Characteristic X-rays are of much less importance in medicine (e.g. in mammography).
X-rays are penetrating radiation which ionise indirectly. As a result of interactions, some of the X-rays are scattered, some are absorbed and the rest is transmitted. This residue is dependent on the different sorts of tissue and their thickness in the irradiated body and is used for X-ray imaging procedures. The absorbed portion is responsible for the image contrast in diagnosis, but also determines the radiation exposure of the patients. In radiation treatment it determines the therapeutic effect.
Glossary entries: Roche and Walter de Gruyter, Berlin