On this Day: Scientist Wilhelm Röntgen Discovers X-rays

In 1895, Wilhelm Conrad Röntgen was the director of the physics department at the University of Wurtzburg and an active professor there. Röntgen had for some time been experimenting with a Lenard tube to produce cathode rays. On Nov. 8, Röntgen was doing experiments in his darkened laboratory that involved covering the Lenard tube with lightproof paper and projecting the cathode rays onto various objects. Röntgen was surprised to see a piece of fluorescent material glowing under exposure to the cathode rays. He repeated the experiment, moving the fluorescent material further and further away from the Lenard tube. He noticed that the fluorescent material glowed up to 2 meters away from the Lenard tube’s cathode rays.

Röntgen knew that the cathode rays could not penetrate the lightproof covering over the Lenard tube, so he hypothesized that the glowing of the fluorescent material must be the result of some new kind of radiation. He began experimenting with putting different materials and objects between the Lenard tube and the fluorescent material and observing how the radiation passed through them. It wasn’t until he had his wife put her hand in the path of the cathode ray that Röntgen made his famous discovery. The shadows from his wife’s hand over a photographic plate clearly showed the bones inside her hand and her wedding ring, while her flesh became transparent. Röntgen named his discovery X-rays because of their unknown properties. On Dec. 28, 1895, Röntgen published his first paper on X-rays and subsequently received dozens of scientific prizes and awards. Most notably, Röntgen was awarded the first-ever Nobel Prize in Physics in 1901 for his work.

One of the first radiology departments was set up at the Glasgow Royal Infirmary in 1896, where many experiments used X-rays to show various injuries and abnormalities. World War I played an important role in expanding the use of X-ray machines. X-ray machines were used in WWI to find and remove bullets and shrapnel. Allied forces began collaborating on the production of X-ray machines and trained radiologists were one of the most sought-after specialists on the front lines, second only to surgeons. After the war ended, the returning veterans brought stories of the X-ray machine back to America and helped spread knowledge of the invention’s usefulness and practicality.

As early as 1896, technicians working closely with X-rays began reporting skin damage and scientist Thomas Edison made reports of eye irritation from working with X-rays. Other reports quickly began to circulate about hair loss, lesions and cancer caused by excessive exposure to X-rays.

More efficient equipment and precautionary measures have significantly reduced the potential harm of X-ray machines. According to the Food and Drug Administration, the health risk posed by X-ray machines is fairly small.