History and Modern Applications of X-Rays We see X-Rays all the time in television, science fiction novels, and comic book superheroes, but what is fact and what is fiction? By examining their makeup, history, modern applications, dangers, protection, and even possible future developments we can understand these scientific marvels far better and more accurately than watching an episode of Star Trek or reading a Superman comic.
First and most important is to analyze why an X-ray works and what it is. These “rays” are high energy, low wavelength beams of electromagnetic energy – very similar to the light we can see; only they are completely invisible to us because our eyes lack the ability to detect its wavelength. They are produced by the movement of electrons in atoms. Electrons exist in constant orbit around an atom’s nucleus in different levels of energy, also known as orbitals.
When an electron makes the transition – drops – to a lower orbital, it needs to release some energy – which it does in the form of a photon. The energy level of this photon corresponds to how far the electron dropped between orbitals. So when a photon collides with another atom, the energy in the photon sometimes gets absorbed and boosts an electron in that atom to a higher level, but only if the amount of energy in the photon (from the 1st electrons drop) matches the energy required to boost the 2nd electron.
Otherwise, the photon will not shift electrons between orbitals. That means that while visible light often has just the right energy to be absorbed by most objects, X-Ray photons will pass through almost everything because they contain far too much energy to be absorbed. Thus, by using a high-voltage vacuum tube to accelerate and release high energy electrons at a large velocity, we are capable of emitting X-rays at one end of an object.
By placing an X-ray detector on the other side, something like a photographic plate, film, screen, or any other type of what is known as an “image receptor” (modern X-rays often have digital outputs), we are capable of capturing information about the object in the middle. That means, unfortunately, that they are nothing like what the Superman comics or fictional “X-Ray specs” sometimes shown in cartoons or science fiction would have us believe, as it does not make sense for an object (such as the lasses or Superman’s eyes) to project X-rays – that would do nothing without a detector on the other side, and for the object to be an X-ray detector would also make no sense as in that case there is no projector. Common misunderstandings like these are perpetuated all the time in popular culture, so to better understand we must examine its origin. The X-Ray was actually discovered on accident by a scientist almost 100 years after the discoveries of the other categories of radiation – Infrared and Ultraviolet – were already discovered.
A scientist named Wilhelm Roentgen stumbled upon their existence in 1896 by accident: he noticed that a fluorescent screen in his lab was glowing when he left an electron beam on, which by itself was expected as fluorescent material is known to glow in response to radiation, but this case was unique because the tube had been surrounded by heavy black cardboard – yet the screen still glowed, even though the cardboard was expected to have blocked most of the radiation.
He began to play with the situation, putting various objects between the tube and the screen – yet it still glowed. Eventually he put his own hand in the path of the radiation and was amazed to see the silhouette of his bones projected onto the screen. Ironically then, the very first usage of X-Rays in its discovery would turn out to be its most practical application to this day.
Medical science uses X-rays to examine broken bones or swallowed or embedded objects in a person’s body, dentistry uses it to pinpoint cavities, and some modified X-rays have even been used to examine thin tissue such as lungs, heart, intestines, and blood vessels to check for irregularities that can subsequently be repaired. The reason X-Rays penetrate the outer layer of the body and not the bones lies in the way that X-Rays are absorbed: whether or not the energy is picked up depends entirely on the kind of atom in the absorber, a relationship that depends on the number of electrons (also known as the atomic number) of the atom.
As such, the large thick areas of calcium atoms in your body (i. e. the bones) are much more capable of absorbing X-Ray photons than the thin tissue of our Carbon and Oxygen based flesh, thus the X-Ray’s pass through the latter while leaving a silhouette of the former. The second major modern application of X-Rays is in the security industry, particularly airport security, which uses the technology to scan incoming luggage for devices that may be able to cause harm on a plane such as a weapon or explosive.
Again, like with medical technology, this has saved countless lives through the clever adaptation of the properties of these high energy beams of radiation. Other uses have been found in the field of astronomy, where detectors are used to pick up X-rays from extremely distant celestial objects and gain an idea of their size and makeup, as well as in industrial manufacturing wherein X-rays are applied to machinery to determine the quality of a weld or correct assembly of parts.
Like any powerful technology, there are also dangers in exposure to X-rays. While the benefits of getting an X-Ray, especially in a situation in which one is faced with a broken bone or other medical emergency, generally far outweigh the risks, it is worth noting that there is no proven “acceptable” threshold for which exposure to radiation does no damage to the body – all additional doses of radiation the body is exposed to slightly increase the risk of getting cancer in your later years.
As such, in instances where X-rays can be avoided – especially in high risk patients like the fetus inside of a pregnant mother – it is generally advised that you do so. On that note, an important facet of any X-ray discussion revolves around exactly what can be used to stop them – as X-Rays go into higher and higher energy levels; it becomes increasingly difficult to find a shield that will prevent them from penetrating. The go-to element at present is Lead, chosen for its low cost and extremely high density which causes it to absorb a large portion of incident X-Rays.
Because of the way the X-Ray works, however, its range through any matter – regardless of density – is theoretically infinite if it is lucky enough to avoid interaction with the atom as it passes through. This is why a simple thin sheet of lead is frequently not sufficient and areas wishing to shield themselves from the radiation will use increasingly thick layers of the material in proportion to the energy of the X-Rays, exponentially increasingly the likelihood that they will be shielded. Finally, what is in store for the future of this technology? While it is mpossible to predict all of what innovators will be able to dream up in the future, we already know some projects currently in development that are set to vastly improve current X-Ray technology, bringing the resultant images into full color and in much higher detail and resolution than ever before, giving unprecedented info to the professionals that will be using them. Others are working on what is called “ultrafast” X-rays, in which snapshots can be taken at lightning-quick speeds, allowing better understanding and manipulation of things that move extremely fast, such as electrons in an atom.
In conclusion, the accidental discovery of the X-Ray – i. e. the high energy, low wavelength portion of the electromagnetic spectrum – has been a boon not just to the medical field but to a wide variety of scientific and commercial endeavors – a merit that seemingly will only grow in the future as more and more applications and advances are discovered for the technology. Who knows, maybe one day the outrageous ideas of science fiction may in fact become a reality!
