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| The First Human X-Ray 1896 |
X-rays are a type of radiation used in imaging and therapy
that come from short wavelength energy beams capable of penetrating most
substances except heavy metals. Just before the turn of the 20th
century in 1895, Wilhelm Rontgen a Prussian Scientist, first detected x-rays
that emitted from a fluorescent glass cathodetube, a surge of electrons
produced when electricity passes through a vacuum tube (Barnett). An invention
by Lenard allowed scientists to study cathode rays flowing out of a vacuum
tube, in addition to rays confined inside one. In air, the rays caused a board
coated with barium platinocyanide to glow with fluorescence. After learning of
this discovery and preparing to witness this phenomenon for himself, Roentgen
switched on the electricity activating the tube but accidentally left the board
propped some feet away. Surprisingly, it glowed despite the amount of space
between the board and the tube. “Since cathode rays could not be present at
that distance, the vacuum tube must also have been emitting another form of
radiation. Unable to identify that, Roentgen himself dubbed it an
"x-ray."”(Barnett). This important discovery eventually led to the
discovery of radioactivity in Uranium by Antoine Henri Becquerel in 1896. However,
it was Roentgen who was the first to take an x-ray photograph in 1896 and who won
the first Nobel Peace Prize for Physics for his discovery in 1901. “He showed
his fellow scientists what he could do by sending photographs of the x-ray of
his wife’s hand, showing only her bones and wedding ring but no tissue.”(Roff,
350).
There are some important differences between a regular print
photograph and an x-ray photograph known now as radiography. They are both
recorded on film, but the processes of how the images are produced diverge
quite a bit. In radiography the film on which the image is being produced is
placed behind the object that is being imaged. The radiation passes through the
image onto the film. Radiation does not pass through bone because of the
calcium or metal as mentioned before in discussion of its discovery. The fact
that it can’t pass through these materials is what gives it the ability to
leave an image on the film.
It was Thomas Edison who developed the first x-ray machines
known as “fluoroscopes”. They became available to the public before the
potential health hazards caused from the technology were fully understood. They
were made available to the public at department stores throughout the US as
curiosity and entertainment objects. People would line up to have their hands
or feet x-rayed for the novelty of seeing pictures of their bones (Roff, 350).
The x-ray photograph’s value to the medical field was seen
right away. Doctors no longer had to cut the body open to see broken bones or
bullet wounds. However, visible negative side effects to patients, physicians,
and scientists exposed to radiation became so obvious that safety precautions
needed to be developed. Everything from burns, hair and tooth loss to
sterilization were experienced from over exposure. Advances in safety
precautions like lead suits and film badge dosimeters were created. By the 1920s
Companies such as Kodak, Siemens, and General Electric were producing and
improving x-ray machines that would be used in the war effort of World War II.
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| Composite image of the supernova remnant W49B. Image Credit: NASA/CXC/SSC/J. Keohane et al.; Infrared: Caltech/Palomar/J.Keohane et al. |
In today’s world, x-ray technology continues to play a
central role in diagnostics for medical treatment in addition to imaging for
multiple scientific fields and the fine arts. It has brought
advancement to astrophysical science through “x-ray astronomy”. In 1999, NASA
launched the Chandra x-ray Observatory, which contains telescopes designed to
detect X-rays. X-rays are produced in the cosmos when matter is heated to
millions of degrees. This use of x-rays in imaging differs from the radiography
image producing process. Instead it is a photographic image of an x-ray that is an amazing image in itself. The clarity of images produced by these
telescopes scientists hope will help answer fundamental questions about
the origin,
evolution, and destiny of the universe.
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| Credit K. Janssens/University of Antwerp http://www.esrf.eu/news/general/van-gogh-cds |
Another valuable role x-ray imaging has is in the conservation
sciences. This field's close relationship to archives is apparent. Identification of materials
and methods used in fabrication of artifacts contribute to a better
understanding of conservation requirements. Inspections in fabrication
processes can be done through x-ray fluorescence. Radiography can reveal the
various layers of pigments and materials used in the creation of everything
from historic structures and artifacts to parchment paper. The Illustration shows where in the painting the
microsamples were taken and an optical-microscope image of the sample. The
overlay indicates the area being studied and the graphs below show the
concentration of the four key compounds.
Radiography is an image producing photographic process
unique in its capture of both man-made and organic material. It has been used
as an art form since the time it was discovered. Though it is no longer a
common practice, there are still artists who continue to produce artwork using
this photographic process. Examples of beautiful x-ray photographs can be seen
on Steven Myers’ website. In his artist statement that accompanies the image
below, he eloquently puts into words the visual attributes that make these
images so unique. “By using x-rays instead of light, an unusual inner-vision
can be revealed, and nature shows us textures, details, and shadows that would
otherwise not be seen.”
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| Steven N. Myers |
Though x-rays images are very different than the photographic
prints and negatives that are typically found in archives, they are never the
less exceptional images that need to be preserved. Their influence in
scientific discoveries, medical conditions, and legal cases are just a few
reasons they are retained by various owning institutions. According to the
National archives website, x-ray film types changed throughout the century, causing them to have a various storage requirements, which are similar to regular photographic
film. The first X rays were recorded on glass plates coated with a photographic
emulsion. In 1918 Eastman Kodak introduced X-ray sheet film coated on both
sides. Over the years there have been three basic film types: nitrocellulose or
nitrate (1910s-1930s), safety cellulose acetate (1920s-mid 1960s), and
polyester (mid 1950s-present). Currently some X rays (and other medical imaging
scans) are made and stored as digital files or scanned from film originals;
either source can be printed out to hard copies on film or paper.
Sources
Barnett, L. "Wilhelm Roentgen." Europe
1789-1914: Encyclopedia of the Age of Industry and Empire. Ed. John
Merriman and Jay Winter. Detroit: Charles Scribner's Sons, 2006. Biography
In Context. Web. 19 Apr. 2013.
Roff, Sue Rabbitt. The Impact of Radioactivity on Medicine
between 1900 and 1949. Science and It’s
Times, Vol.6, pg. 349-352.
Janssens, K. “X-rays unravel mysterious degradation of a Van
Gogh painting” University of Antwerp. Web. 21 Apr. 2013. http://www.esrf.eu/news/general/van-gogh-cds
http://www.archives.gov/records-mgmt/publications/managing-xray-films.html
http://www.nasa.gov/mission_pages/chandra/astronomy/index.html
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