German physicist Wilhelm Röntgen is usually credited as the discoverer of X-rays in 1895, because he was the first to systematically study them, though he is not the first to have observed their effects. He is also the one who gave them the name “X-rays” though many others referred to these as “Röntgen rays” (and the associated X-ray radiograms as, “Röntgenograms”) for several decades after their discovery and even to this day in some languages, including Röntgen’s native German.
X-rays were found emanating from Crookes tubes, experimental discharge tubes invented around 1875, by scientists investigating the cathode rays, that is energetic electron beams, that were first created in the tubes. Crookes tubes created free electrons by ionization of the residual air in the tube by a high DC voltage of anywhere between a few kilovolts and 100 kV. This voltage accelerated the electrons coming from the cathode to a high enough velocity that they created X-rays when they struck the anode or the glass wall of the tube. Many of the early Crookes tubes undoubtedly radiated X-rays, because early researchers noticed effects that were attributable to them, as detailed below. Wilhelm Röntgen was the first to systematically study them, in 1895.
The discovery of X-rays stimulated a veritable sensation. Röntgen’s biographer Otto Glasser estimated that, in 1896 alone, as many as 49 essays and 1044 articles about the new rays were published. This was probably a conservative estimate, if one considers that nearly every paper around the world extensively reported about the new discovery, with a magazine such as Science dedicating as many as 23 articles to it in that year alone. Sensationalist reactions to the new discovery included publications linking the new kind of rays to occult and paranormal theories, such as telepathy.
A man receiving an x-ray in Austria, circa 1910. (Imagno—Getty Images)
A chest X-ray in progress at Professor Menard’s radiology department at the Cochin hospital, Paris, 1914. (Jacques Boyer/Roger Viollet—Getty Images)
One of the advanced wonders at the Roentgen Institute, the modern Roentgen ‘look through’ machine, which prevents any injury to the treating physician, Frankfurt, Germany, circa 1929. (Underwood Archives—Getty Images)
A man and a woman demonstrating medical equipment at a X-ray exhibition, beside a sign reading ‘The Metalix Tube for Therapy,’ 1928. (Puttnam—Getty Images)
Filmstar Judith Allen with the radiograph of her back, circa 1930. (Imagno—Getty Images)
An x-ray demonstration with the latest x-ray apparatus. London. 1932. (Imagno—Getty Images)
The latest X-ray apparatus being operated by an radiologist wearing the old-type protectors which are no longer necessary with modern apparatus. Radiological exhibition. Central Hall. Westminster, 1934. (Imagno—Getty Images)
A woman having her head x-rayed with the new shock-proof apparatus at the London Medical Exhibition, Royal Horticultural Hall. The apparatus, which is designed for the consulting room, is simple to use as it can be plugged in to any domestic lighting point’. 1934. (SSPL—Getty Images)
In October 1937 in Rio de Janeiro, a radiograph invented by Professor physicist Moraes De Abreu to detect lung diseases, called Roentgen-Photographie was used on a patient. (Keystone-France/Gamma-Keystone via Getty Images)
An x-ray technician with the US Medical Corps tending to a wounded soldier during World War Two, circa 1941-1945. (US Army Signal Corps—Getty Images)
Doctors using x-ray machine to feed venous catherter into patient’s heart, 1947. (Al Fenn—The LIFE Picture Collection/Getty Images)
Small child being given chest x-ray at Chelsea Chest Clinic, 1949. (Cornell Capa—The LIFE Picture Collection/Getty Images)
X-ray machine, at the California dental association exhibit, California state fair, 1953. (Jon Brenneis—The LIFE Images Collection/Getty Images)
A desperate patient who has hiccups is x-rayed at the Flower-Fifth hospital Hospital in New York, 1955. (Three Lions—Getty Images)
X-ray machine which circles head to take panoramic picture of teeth, eliminating usual mouthful of film, 1960. (John Loengard—The LIFE Picture Collection/Getty Images)