BBC Knowledge Asia Edition - December 2014

HOW DO WE KNOW?

stomach, which he used to

diagnose a child’s appendicitis. It

is still used today to visualise blockages

and tumours. Later, iodine-based contrast

mediums were developed for the imaging

of the circulatory system and the kidneys.

In parallel with traditional X-ray

imaging, fluoroscopy was developed.

This technique uses the same principle as

X-ray imaging but instead of producing

still images, doctors can see inside

the body in real-time. The earliest

fluoroscopes, produced in the months

after Röntgen’s discovery, were funnel-

shaped. The user would look through a

gap in the thinnest end, and the wider

end was covered with a thin piece of

cardboard painted with a metal salt called

barium platinocyanide, which fluoresces

when X-rays hit it. The patient was

placed between an X-ray source and the

fluoroscope, and the user was able to see

an image of them on the cardboard.

Inventor Thomas Edison produced

the first commercial fluoroscope in

the early 1900s, in which the barium

platinocyanide had been replaced with

calcium tungstate, which fluoresces more

brightly. Even with his adaptation, the

fluorescence was too dim to be seen in

daylight, and early users of fluoroscopes

had to carry out their work in dark

rooms, after allowing their eyes to adapt

to the dark. This problem was alleviated

in part by special goggles in 1916, and

then by image intensifiers. Invented in the

1940s, these convert the fluorescence into

visible light. In the 1950s, fluoroscopes

were hooked up to CCTV cameras.

Now doctors could see images on a

screen in a separate room, away from

the X-rays. Today fluoroscopy is used to

guide surgery in real-time – in pinning

broken bones, for example.

Computer power

When you see a single X-ray image

such as one held up to the light by an

actor on TV, it’s an image taken from

just one angle. This means the body’s

organs and bones are superimposed and

difficult to analyse alone. In the 1930s,

Italian radiologist Alessandro Vallebona

proposed a technique that would produce

clear images of ‘slices’ of the body by

Being able to peer inside the body revolutionised medicine,

and took just under a hundred years to develop

TIMELINE

PHOTO: SCIENCE & SOCIETY X3, SCIENCE PHOTO LIBRARY, LUCIEN MONFILS/WIKIPEDIA, THINKSTOCK

Kodak

introduces

radiographic

film, replacing

photosensitive

glass plates.

Wilhelm Röntgen

discovers X-rays while

experimenting with

cathode ray tubes.

Within weeks of

publication, scientists and

the public alike are excited

by the possibilities.

Thomas Edison

invents the first

commercial

fluoroscope, a

device with which

one can view the

inside of the body in

real-time.

1900

1895

1906

French immunologist-turned-radiologist

Antoine Béclère uses a contrast agent for the

first time, giving a young girl a barium meal to

diagnose her appendicitis using X-rays.

General Electric’s William Coolidge invents the

hot-cathode X-ray tube, improving the reliability

and safety of X-ray sources.

Godfrey

Hounsfield’s

prototype CT

scanner is used

on a patient for

the first time and

reveals that the

41-year-old woman

has a brain tumour.

1913

1971

1918