The discovery of X-rays

The discovery of the X-rays may be described as one of the major discoveries of physics, which symbolized the birth of modern physics. The study of cathode rays was of immense interest during the nineteenth century. British and American scientists of the late nineteenth century studying radiation noticed that photographic plates placed near a glass tube got fogged when an electrical discharge is passed through it. Jennings and Goodspeed was fascinated by the phenomenon such that they wanted to keep the fogged materials as a memento. William Crookes of England, who also constructed the Crookes tube, thought that the plates were faulty and had it sent back to Ilford. Crookes found some shadows on unexposed photographic plates placed near the tube, but did not investigate it further. In 1892, Heinrich Hertz observed that cathode rays could penetrate thin metal foils like aluminum, which was further studied by his student Philip Lenard. Lenard developed a cathode tube and studied X-ray penetration through various mediums, not realizing that he was producing X-rays.  In April 1887, a Serbian American physicist Nikola Tesla investigated the X-rays with high voltages and vacuum tubes. It is evident from Nikola Teslas publications that he developed a single electrode X-ray tube, which differed from other such tubes, as it had no target electrode. Although Tesla performed several such experiments, he did not declare them publicity. His later experimentation was instrumental in alerting the scientific community to the hazards of X-ray exposure.

Although many scientists were involved with the understanding of X-rays, it was Roentgen who observed, documented and formerly put forth the phenomenon of X-rays. This was the first, formal recognition of the new found X-rays. On the November 8th, 1895, the German physicist Wilhelm Roentgen was studying cathode rays. Cathode rays are the phosphorescent electron stream, used in fluorescent bulbs, televisions etc. Roentgen was focused on the effects of electrical discharge through low pressure gas. He however noticed something he hadnt observed in his earlier studies. The cathode ray tube produced weak rays, which caused a screen to glow or fluoresce. The rays were seen to pass through materials like aluminum, paper, wood etc (Pagewise, 2002). He further observed that a surface coated with barium platinocyanide and hidden from the light of discharge would still glow. Roentgen wanted to determine if cathode rays could escape from a glass tube, when enclosed with a black cardboard. To his surprise he noticed a glow appear in his dark laboratory even at a considerable distance from the cardboard enclosed glass tube. Initially Roentgen thought there was a tear in the sheathing enclosure, which allowed the light to leak (Krock, 2001). He soon realized he had stumbled upon something different. He put his hand between the screen and the tube and saw an image of the bones of his hand (School science, 2010). He then replaced the screen with a photographic plate to capture the image.  Roentgen concluded his findings, which were indeed ground breaking. He had identified a previously unknown radiation, a new type of ray.

Through his further experimentation, Roentgen determined that the new ray could even penetrate the walls of the laboratory. Roentgen tested the rays with water, carbon dioxide and liquids and realized that all were transparent to the ray. After about six weeks of study, Roentgen confirmed his new findings. Subsequently on December 22nd, 1895, Roentgen and his wife took the first X-ray picture. On December 28, 1895, Roentgen delivered a paper, The preliminary study of a new ray at the university of Wurzburg in Germany. He admitted in his paper that he did not know the exact nature of the discovered rays. He therefore called them X-rays, as in mathematics x referred to the unknown parameter.

Roentgens discovery opened up new possibilities for the doctors. Using the new radiation, doctors could visualize the skeletal system of the human body. Earlier it was difficult to determine the location of bone break and the way it could be set right. The result was that many people had deformed limbs and arms even after setting. It was too difficult or nearly impossible to understand the location of break and the position of the bones, so as to ensure a seamless joint. Using the new radiation now, broken bones could be observed through the flesh. Roentgen contacted the physical medical society and informed them of his findings. Subsequently Roentgen received the first Nobel Prize for physics in 1901. Very few discoveries have had the recognition and euphoria as the X-ray. Over 1000 books and articles on the subject were released within one year of Roentgens discovery.

The use of X-rays in medical field was in 1896 when American physiologist Walter Bradford Cannon tracked the movement of barium sulfate inside an animals digestive system using a fluorescent screen. This was made possible by Thomas Alva Edison who had invented the X-ray fluoroscope earlier. Very soon physicians were using X-rays throughout the world to look for broken bones and bullets in humans. Some doctors even used X-rays to treat skin diseases, while many anticipated its use in curing tuberculosis or eradicating bacteria. Some even thought that X-rays could restore sight among the blind. By the year 1896, the Glasgow Royal Infirmary had also set up an X-ray department, which was one of the earliest in the world. Dr. John McIntyre, the head of the department produced notable X-rays including the first X-ray of a kidney stone, a coin stuck in a childs throat and the movement of a frogs legs. In the two decades following Roentgens discovery, X-rays were already deployed in treating WWI soldiers.

Subsequent to Roentgen, many physicians were vigorously involved in research and exploration with X-rays. The X-rays produced are normally unpolarized, constituted by both horizontally and vertically polarized rays. Physicists were aware that light was an electromagnetic wave and suspected the unchanged X-rays were electromagnetic waves too. Roentgen confirmed that the X-rays were not bent while traveling from one medium to another, thus not undergoing any deviation. Unlike light, the X-rays are not refracted while being incident on a material surface. X-rays are reflected diffusely and are not diffracted. The X-rays on striking an object generates secondary rays that are less penetrating than the incident ones. British scientist Charles Barkla in 1902 showed that the X-ray secondary emission was of two types (Skullsinthestars, 2010). One was an unchanged scattering and another fluorescent radiation corresponding to the particular substance. He noticed the polarization of X-rays, which indicated its resemblance to ordinary light. These contributions were valuable to the understanding and knowledge of the photographic action and absorption of X-rays. In 1917, Barkla was awarded the Noble Prize for physics.

The benefits of X-ray are easily evident, not only in the field of medicine but in industry too. However it is in medicine where X-rays count most. The discovery of X-rays and its adaptation to its present usage state has been made possible not just by Roentgen but several others too. It is the ultimate result of the efforts of several dedicated people, who contributed to it in their own way. The X-ray machine and its understanding, like all other developments constantly evolve to improve and provide better.  The X-ray machines of today include sophisticated CT scanners, computerized tomography (CT)

Scanners etc., which help in complex surgery and radiotherapy.

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