Rentgen

Rentgen refers to X-ray radiation and imaging in several languages, named after Wilhelm Conrad Röntgen, a German physicist who discovered X-rays in 1895. The name also appears in some contexts as the old unit of exposure, the roentgen (often spelled rentgen in non-English texts), which is historical and largely superseded by SI units.

Discovery and impact

On 8 November 1895, while experimenting with a Crookes tube, Röntgen observed a fluorescent screen glow through a covered window, even though the tube was shielded. He realized a new kind of penetrating radiation was being emitted and could pass through matter to expose photographic plates. He published his findings in a concise note and soon demonstrated that X-rays could photograph the internal structure of the hand. In 1901, Röntgen received the Nobel Prize in Physics for this discovery, which rapidly transformed medicine and imaging science.

Nature and properties

X-rays are a form of electromagnetic radiation with wavelengths shorter than visible light. They are ionizing and capable of removing electrons from atoms, which carries a risk of biological damage with high or repeated exposure. Their interaction with matter depends on density and composition; dense materials like bone absorb more X-rays than soft tissue, enabling radiographic imaging. X-ray production typically involves high-energy electrons striking a metal target in an X-ray tube or using synchrotron sources.

Uses and safety

The primary use is medical imaging, including radiography and computed tomography, supplemented by industrial nondestructive testing, security screening, and scientific research. Because X-rays are ionizing, exposure is regulated to minimize risk, using shielding, dose optimization, and justification of procedures. Common dose units include gray for absorbed dose and sievert for effective dose; the historical roentgen/rentgen unit is largely obsolete in modern practice.