X-rays were discovered accidentally in 1895 by the German physicist Wilhelm Roentgen

The fact that x-rays could reveal the skeleton within its case of flesh without any apparent harm, was startling

The fact that x-rays could reveal the skeleton within its case of flesh without any apparent harm, was startling.


More on History of x-rays

Roentgen refused to take out any patents, so that the world could freely bebefit from his discovery.


Photographs of historical interest

Significant dates in x-rays development appear in the Timeline, below....


A century of development in x-rays

X-rays progressed from the physics lab to widespread use in medicine remarkably quickly


Roentgen and the Nobel prize

Users of x-rays in the early days, took few precautions and many died prematurely from over-exposure.

X-rays were discovered accidentally in 1895 by the German physicist Wilhelm Roentgen. He was working with a cathode ray tube when he noticed an unexpected glow about two metres from the tube, coming from some barium platinocyanide (a fluorescent material). Given that the cathode ray tube was in a black cardboard box, the cathode rays could not have reached the fluorescent material. Clearly a more penetrating radiation was responsible. Not yet knowing what kind of rays they were, he called them x-rays.

When he placed his hand in their path he found that
human flesh is transparent to x-rays but that
bones are not.



Roentgen soon found that photographic plates were sensitive to the newly discovered rays. He convinced his wife to participate in an experiment. When the image of Bertha's hand was developed, the bones of her hand and the two rings she wore were clearly visible. She was horrified at the result, as she saw in the image a premonition of death.

The picture of Bertha Roentgen's hand, taken on 22nd Dec.1895, was soon displayed in newspapers and scientific publications all over Europe and the United States.




It is probably hard for us to imagine today, how eerie this image was at the time. The fact that x-rays could reveal the skeleton within its case of flesh without any apparent harm, was startling. The interest it generated, triggered a good deal of research into x-rays and related effects. Doctors were quick to recognise the medical potential revealed in Roentgen's first x-ray of his wife's hand.

Before publishing the photograph of Bertha’s hand, Roentgen investigated and identified most of the properties of x-rays. In particular, he identified that x-rays cause ionisation.

x-rays are unaffected by electric and magnetic fields
X-rays resembled cathode rays in so far as they both cause ionisation. However cathode rays are deflected by electric and magnetic fields unlike x-rays.

  X-ray timeline
1895 Roentgen identified most of the properties of x-rays
1896 The first clinical use of x-rays when two British doctors used them to find
a needle in a woman’s hand.
1896 The military first used x-rays in Naples, to locate bullets in the forearms of
two soldiers who had been wounded in Italy’s Ethiopian campaign.
1899 Haga and Wind noticed a slight broadening of an x-ray beam after it passed through a slit, a few thousandths of a millimetre wide, suggesting the possibility of diffraction if a narrow-enough slit could be found.
1901 Roentgen received the first Nobel prize for physics for his discovery.
1906 Barkla successfully polarized x-rays, confirming their wave nature.
1906 Beclere first used x-rays to diagnose a stomach disorder by first giving the patient a meal of bismuth.
1907 Mutation by x-ray reported in toads by Bardeen.
1912 Max von Laue predicted and discovered that x-rays could be diffracted by
crystals.
1913 Bragg successfully analysed an x-ray diffraction pattern, which offered a
major break through in crystallography.
1913 Hot cathode x-ray tubes and tungsten targets permitting higher voltages,
first introduced by Coolidge.
1922 Film badges for personnel monitoring -----
developed by G. Pfahler.
1931 Tomography developed
1948 First experimental x-ray image intensifier developed by Coltman.
1972 The CAT scanner (based on x-rays) was invented by Godfrey Hounsfield.