museum

Wilhelm Röntgen and X-rays

Biography

• Röntgen was born in Lennep in Rhenish Prussia as the only child of a merchant and manufacturer of cloth. His mother was Charlotte Constanze Frowein of Amsterdam. In 1848, the family moved to Apeldoorn and Wilhelm was raised in the Netherlands. He received his early education at the boarding school, Institute of Martinus Herman van Doorn, in Apeldoorn. From 1861 to 1863, he attended the ambachtsschool in Utrecht. He was expelled for refusing to reveal the identity of a classmate guilty of drawing an unflattering portrait of one of the school's teachers.

• In 1865, he tried to attend the University of Utrecht without having the necessary credentials required for a regular student. Upon hearing that he could enter the Federal Polytechnic Institute in Zurich, he passed its examinations, and began studies there as a student of mechanical engineering. In 1869, he graduated with a Ph.D. from the University of Zurich; once there, he became a favorite student of Professor August Kundt, whom he followed to the University of Strassburg in 1873.

Career• In 1874 Röntgen became a lecturer at the University of

Strassburg. In 1875 he became a professor at the Academy of Agriculture at Hohenheim, Württemberg. He returned to Strassburg as a professor of physics in 1876, and in 1879, he was appointed to the chair of physics at the University of Giessen. In 1888, he obtained the physics chair at the University of Würzburg, and in 1900 at the University of Munich, by special request of the Bavarian government. Röntgen had family in Iowa in the United States and at one time planned to emigrate. Although he accepted an appointment at Columbia University in New York City and had actually purchased transatlantic tickets, the outbreak of World War I changed his plans and he remained in Munich for the rest of his career.

• During 1895 Röntgen was investigating the external effects from the various types of vacuum tube equipment when an electrical discharge is passed through them. Röntgen speculated that a new kind of ray might be responsible. In early November he was repeating an experiment with one of the tubes in which a thin aluminum window had been added to permit the cathode rays to exit the tube but a cardboard covering was added to protect the aluminum from damage by the strong electrostatic field that is necessary to produce the cathode rays. He knew the cardboard covering prevented light from escaping, yet Röntgen observed that the invisible cathode rays caused a fluorescent effect on a small cardboard screen painted with barium platinocyanide when it was placed close to the aluminum window. It occurred to Röntgen that the Hittorf-Crookes tube, which had a much thicker glass wall than the Lenard tube, might also cause this fluorescent effect.

• He repeated his experiments and made his first notes. In the following weeks he ate and slept in his laboratory as he investigated many properties of the new rays he temporarily termed X-rays, using the mathematical designation for something unknown. Although the new rays would eventually come to bear his name in many languages where they became known as Röntgen Rays, he always preferred the term X-rays. Nearly two weeks after his discovery, he took the very first picture using x-rays of his wife's hand, Anna Bertha. When she saw her skeleton she exclaimed "I have seen my death!"

• Röntgen determined to test his idea. He carefully constructed a black cardboard covering similar to the one he had used on the Lenard tube. Before setting up the barium platinocyanide screen to test his idea, Röntgen darkened the room to test the opacity of his cardboard cover. As he passed the Ruhmkorff coil charge through the tube, he determined that the cover was light-tight and turned to prepare the next step of the experiment. It was at this point that Röntgen noticed a faint shimmering from a bench a meter away from the tube. To be sure, he tried several more discharges and saw the same shimmering each time. Striking a match, he discovered the shimmering had come from the location of the barium platinocyanide screen he had been intending to use next.

• Röntgen's original paper, "On A New Kind Of Rays" was published 50 days later on 28 December 1895. On 5 January 1896, an Austrian newspaper reported Röntgen's discovery of a new type of radiation. Röntgen was awarded an honorary Doctor of Medicine degree from the University of Würzburg after his discovery. He published a total of three papers on X-rays between 1895 and 1897. Today, Röntgen is considered the father of diagnostic radiology, the medical specialty which uses imaging to diagnose disease.

• In 1901 Röntgen was awarded the very first Nobel Prize in Physics. The award was officially "in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him". Röntgen donated the monetary reward from his Nobel Prize to his university. Röntgen refused to take out patents related to his discovery, as he wanted mankind as a whole to benefit from practical applications of the same (personal statement). He did not even want the rays to be named after him.

X-rays

• X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3 × 1016 Hz to 3 × 1019 Hz) and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma rays. In many languages, X-radiation is called Röntgen radiation, after Wilhelm Conrad Röntgen

Medical use• Since Röntgen's discovery that X-rays can identify bone structures, X-

rays have been developed for their use in medical imaging, the first use was less than a month after his seminal paper on the subject. Radiology is a specialized field of medicine. Radiologists employ radiography and other techniques for diagnostic imaging. This is probably the most common use of X-ray technology.

• X-rays are especially useful in the detection of pathology of the skeletal system, but are also useful for detecting some disease processes in soft tissue. Some notable examples are the very common chest X-ray, which can be used to identify lung diseases such as pneumonia, lung cancer or pulmonary edema, and the abdominal X-ray, which can detect intestinal obstruction, free air (from visceral perforations) and free fluid (in ascites). X-rays may also be used to detect pathology such as gallstones (which are rarely radiopaque) or kidney stones which are often (but not always) visible.