X-Ray
History of the X-Ray
By Mary Bellis
All light and radio waves
belong to the electromagnetic spectrum and are all considered different types
of electromagnetic waves, including:
· microwaves
and infrared bands whose waves are longer than those of visible light (between
radio and the visible)
· and
UV, EUV, X-rays, and g-rays (gamma rays) with shorter wavelengths.
The electromagnetic nature of
x-rays became evident when it was found that crystals bent their path in
the same way as gratings bent visible light: the orderly rows of atoms in the
crystal acted like the grooves of a grating.
MEDICAL X-RAYS
X-rays
are capable of penetrating some thickness of matter.
Medical x-rays are produced
by letting a stream of fast electrons come to a sudden stop at a metal plate;
it is believed that X-rays emitted by the Sun or stars also come from fast
electrons.
The images produced by X-rays
are due to the different absorption rates of different tissues.
Calcium in bones absorbs
X-rays the most, so bones look white on a film recording of the X-ray image,
called a radiograph.
Fat and other soft tissues
absorb less and look gray. Air absorbs the least, so lungs look black on a
radiograph.
WILHELM CONRAD RÖNTGEN - FIRST X-RAY
On 8
Nov 1895, Wilhelm Conrad Röntgen (accidentally) discovered an image cast from his
cathode ray generator, projected far beyond the possible range of the cathode
rays (now known as an electron beam).
Further investigation showed
that the rays were generated at the point of contact of the cathode ray beam on
the interior of the vacuum tube, that they were not deflected by magnetic
fields, and they penetrated many kinds of matter.
A week after his discovery,
Rontgen took an X-ray photograph of his wife's hand which clearly revealed her
wedding ring and her bones.
The photograph electrified
the general public and aroused great scientific interest in the new form of
radiation.
Röntgen named the new form of
radiation X-radiation (X standing for "Unknown").
Hence
the term X-rays (also referred as Röntgen rays, though this term is unusual
outside of Germany).
WILLIAM COOLIDGE & X-RAY TUBE
William
Coolidge invented the X-ray tube popularly called the Coolidge tube.
His invention revolutionized
the generation of X-rays and is the model upon which all X-ray tubes for
medical applications are based.
Other inventions of Coolidge:
invention of ductile tungsten
A breakthrough in tungsten
applications was made by W. D. Coolidge in 1903.
Coolidge succeeded in
preparing a ductile tungsten wire by doping tungsten oxide before reduction.
The resulting metal powder
was pressed, sintered and forged to thin rods. A Very thin wire was then drawn
from these rods.
This was the beginning of
tungsten powder metallurgy, which was instrumental in the rapid development of
the lamp industry - International Tungsten Industry Association (ITIA)
A computed tomography scan or
CAT-scan uses X-rays to create images of the body.
However, a radiograph (x-ray)
and a CAT-scan show different types of information.
An x-ray is a two-dimensional
picture and a CAT-scan is three-dimensional.
By imaging and looking at
several three-dimensional slices of a body (like slices of bread) a doctor
could not only tell if a tumor is present but roughly how deep it is in
the body.
These
slices are no less than 3-5 mm apart. The newer spiral (also called helical)
CAT-scan takes continuous pictures of the body in a spiral motion so that
there are no gaps in the pictures collected.
A CAT-scan can be three
dimensional because the information about how much of the X-rays are passing
through a body is collected not just on a flat piece of film, but on a
computer.
The data from a CAT-scan can
then be computer-enhanced to be more sensitive than a plain radiograph.
INVENTOR OF THE CAT-SCAN
Robert
Ledley was the inventor of CAT-Scans a diagnostic x-Ray system.
Robert Ledley was granted
patent #3,922,552 on November 25th in 1975 for a "diagnostic X-ray
systems" also known as CAT-Scans.
Mary
Bellis has been writing about inventors since
1997. She also loves to tinker (invent) and spends too much time in her
workshop developing her ideas.
EXPERIENCE
Forbes Best of the Web credits Mary for creating the number one online
destination for information about inventors and inventions. Her writing has
been reprinted and referenced to in numerous educational books and articles.
Her opinion and advice is requested by media outlets on a constant basis. In
addition, she has produced and directed a number of films, including a
documentary on Alexander Graham Bell, the inventor of the telephone, and has
worked as a curator specializing in computer generated art.
EDUCATION
Mary has
two degrees in film and animation from the San Francisco Art Institute. She is
a big fan of both history and technology and an avid reader of books and
periodicals on those topics.
MARY BELLIS
I have a
passion for inventing and a deep respect for all inventors. I know firsthand
the difficulties that inventors face and I want to help by making the path from
idea to marketplace a clearer process.
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