Producing X-rays
Wilhelm Rontgen produced X-rays by passing an electric current across metal electrodes embedded in the wall of a glass tube from which most of the air had been removed. It was later worked out that X-rays had been produced when stream of electrons generated at the negative electrode hit a target.
In Rontgen’s experiments the target had been the glass wall of the tube. Modern X-ray tubes are the result of many technical improvements to this basic apparatus, which was fragile, unreliable and at times dangerous.

X-ray Machines
Within a few decades of Rontgen’s experiments, doctors could buy complete X-ray machines incorporating an X-ray tube and stand , a control panel, an adjustable patient couch and a film holder. Film was introduced after World War 1 replacing the original fragile glass plates. Procedures for developing the films in the dark room became standardised.
 

X-rays for diagnosis
X-ray pictures of bones were quite easy to understand, but it took doctors longer to agree on the more hazy shadows of chest and abdominal organs meant. Getting ‘contrast media’ - substances which show up on X-ray - into the body helped doctors see hollow organs like the gut. Bismuth was first used for this, then barium, which is still used today. Other contrast media were found that could be safely injectedinto blood vessels, sometimes through fine tubes in serted as far as the heart. By the 1950s mostorgan systems could be shown up like this.
 

Moving pictures
Techniques for seeing ‘real time’ moving X-ray images, using a fluorescent screen instead of film, had been known since the beginnings of X-ray work. But these images were dim and almost impossible to record permenently. Developments in electronics especially television, have meant that X-ray images can now be viewed on TV monitors and recorded on videotape. Doctors can see exactly what they’re doing - for example, if they’re inserting a fine tube into progres on the monitors.