Xsäteily

Xsäteily is the Finnish term commonly used for X-rays, a form of electromagnetic radiation with wavelengths roughly between 0.01 and 10 nanometres and photon energies from about 100 electronvolts to several hundred kiloelectronvolts. First observed by Wilhelm Conrad Röntgen in 1895, X-rays were initially called "X" to denote an unknown type of radiation and are sometimes referred to as Röntgen radiation in several languages.

X-rays are produced when high-energy electrons are decelerated in matter (bremsstrahlung) or when electronic transitions in atoms generate characteristic spectral lines. Sources include X-ray tubes, synchrotrons and certain radioactive decays. They are classified into soft and hard X-rays based on energy, and are distinguished from gamma rays mainly by their origin rather than by energy.

Applications of X-rays are wide-ranging: medical imaging (radiography, computed tomography, fluoroscopy, mammography), dental diagnostics, industrial inspection, security scanning, crystallography and materials analysis, and astronomical observations of high-energy phenomena. Their strong penetrating power and interaction with matter make them valuable for imaging internal structure and determining crystal and electronic properties.

Because X-rays are ionizing radiation, exposure carries health risks such as tissue damage and increased cancer risk. Use is regulated and controlled through dose limits, shielding, minimization protocols and the ALARA (as low as reasonably achievable) principle to reduce unnecessary exposure.