An Accidental Discovery? A Brief History of the X-Ray

X-rays are one of the most commonly used diagnostic imaging tests performed within the healthcare industry. X-rays are a type of electromagnetic radiation similar to regular light rays. However, unlike regular light, X-rays have shorter wavelengths, making it impossible for the human eye to see. X-rays also have higher energy and can pass through most objects. As a result, X-ray machines are able to take photographs of the inside of an object or person in the same way that a regular camera uses regular light to take pictures of the outside of an object or person.

To produce an X-ray image, X-ray machines create X-ray photons, which are concentrated beams of electrons. These beams are absorbed at different rates within the body. Soft tissue, such as skin and organs, are unable to absorb these energy rays, which means that they pass right through. It’s the denser parts of the body, such as the bone, that absorbs the radiation, thereby allowing an image of the inside of the body to be developed. The x-ray that is not absorbed exits the other side of the body and then comes into contact with a digital detector. The detector converts the x-ray energy into visible light to produce the image.

Although they have lots of uses both in and outside of the medical community, they are used most often to examine and diagnose issues that patients are having, to monitor diagnosed diseases, and to track how effectively prescribed treatments are working.

How Were X-Rays Discovered?

As technologically advanced as X-rays may seem (in particular, the X-ray machines that actually produce the images), the X-ray itself was discovered a long time ago. The German physicist Wilhelm Conrad Rontgen is credited for having discovered the X-ray back in 1895. What’s even more incredible is that he discovered it purely by accident. He ended up receiving the very first Nobel Prize in Physics in 1901 for his work.

At the time of the discovery, Rontgen was performing tests using cathode rays to determine whether they could pass through glass. He had been working with a tube consisting of a glass bulb with positive and negative electrodes encapsulated in it. Rontgen evacuated the air inside the tube and then applied a high voltage. This caused the tube to produce a fluorescent glow. He then used heavy black cardboard to shield the tube. When he did this, he discovered a glow coming from a chemically coated screen located near the tube. He realized that some sort of ray was able to pass through the cardboard. Upon further inspection, he realized that they could also pass through the books and papers located on his desk.

He called the rays that were producing this glow “X-rays” because of their mysterious nature (the “X” represented an unknown type of radiation). Rontgen pivoted from his study of cathode rays to the study of these new X-rays, which consisted of wavelengths that are 1,000 times shorter than the wavelengths of regular light. Soon after discovering X-rays, Rontgen discovered their medical use after taking a photograph of his wife’s hand using X-rays. This resulted in an image of her hand’s skeletal structure. Upon seeing the image of her hand, his wife commented that she had seen her own death.

Rontgen published his findings two months after his discovery. Scientists all over the world immediately began to study X-rays and their potential, including Thomas Edison and Nikola Tesla. Most radiologist’s are aware of Nikola Tesla’s research in the field of electromagnetism. The International System (SI) unit of magnetic flux density, the Teslacon magnetic resonance imager, and Teslascan manganese contrast agent were all named after him. But if the discovery of x-rays is mentioned, only a few radiologists associate it with Tesla’s name. Edison, however, developed the fluoroscope, which would become the standard for medical X-ray exams, only a year after X-rays were discovered.

One of the reasons that X-ray technology was able to advance so quickly was because Rontgen never applied for a patent for his findings. This allowed everyone to have access to his discovery right away, to the greater benefit of the medical community.

X-Rays for Medical Use

X-rays have become incredibly useful for a wide range of medical conditions. The following are a few examples of some of the most common medical uses:Chest X-rays – used to help identify lung diseases, including lung cancer, pulmonary edema, and pneumonia.Abdominal X-rays – used to detect bowel obstructions, free fluid caused by ascites, and free air caused by visceral perforations. They can sometimes be used to identify gallstones and kidney stones as well.Dental X-rays – most commonly used to help identify cavities in the teeth.Computed tomography – also known as CT scanning, is a process in which numerous X-ray images are taken in different angles to produce cross-section images of specific areas of the body. These images can then be combined into a 3-D image for more accurate diagnostic purposes. CT scanning was first conceived as an idea by Godfrey Hounsfield in 1967. The first CT scan of a brain was performed in 1971.Fluoroscopy – process in which a fluoroscope is used to produce real-time moving images of a patient’s internal structures. Fluoroscopes consist of X-ray image intensifiers and CCD video cameras. They are commonly used to identify coronary artery blockages, swallowing disorders, and esophageal disorders.Radiotherapy – process in which X-rays are used as a treatment for managing cancer. Low energy X-rays are used to treat skin cancers, while high energy X-rays are used for brain, breast, lung, and prostate cancers.

Unfortunately, early X-Ray machines had some serious drawbacks. Few realized that X-rays could be harmful until scientists begun to experience the effects of prolonged exposure to X-rays without shielding. For example, both Edison and Tesla reported eye irritations as a result of their experimentation with X-rays. In fact, one of Edison’s glassblowers, Clarence Madison Dally, developed cancer in both his hands as a result of testing X-ray tubes on his hands. The cancer was so advanced that his arms had to be amputated in a failed attempt to save his life. Edison ceased working with X-rays following Dally’s death.Several other incidents soon proved that X-rays could be quite dangerous. For example, Dr. William Lofland Dudley reported hair loss after being the subject of an X-ray image. Dr. HD Hawks and Tesla both reported burns as a result of X-ray demonstrations as well.These incidents occurred because X-rays are radioactive. However, such safety risks rarely exist today due to the low dosage of radiation used. Scientists eventually discovered how to control how much radiation was used in taking X-ray images and what was a safe amount of exposure.Present-day X-rays have almost no adverse effects on patients. Everyone is exposed to natural background radiation on a daily basis – the amount of radiation a patient is exposed to in a chest X-ray is about the equivalent of ten days worth of normal background radiation we are all exposure to, meaning it should have no effect on the patient.This doesn’t mean that there are no side effects to speak of. In very rare cases, a patient might experience hives, itching, nausea, or lightheadedness following an X-ray, but only if they ingested a contrast material prior to the test. Pregnant women are discouraged from getting X-rays as well since it’s not worth the risk of exposing a fetus to any amount of radiation.

X-Rays Have Had Many Other Uses As Well

Although X-rays are more commonly known for their use in the medical field, X-ray technology has many different uses as well. The following are a few examples of the different uses of X-rays throughout the last century or so:

Shoe Fitting

One of the more obscure applications of X-ray technology was a shoe-fitting fluoroscope. There is a bit of controversy over who invented the device. Although Clarence Karrer claims to have invented the shoe-fitting fluoroscope in 1924 to assist an orthopedic shoe manufacturer, a patent was granted to Jacob Lowe in 1927 for building a shoe-fitting fluoroscope as a way to diagnose foot problems in veterans.

The shoe-fitting fluoroscope became quite popular during this time among store clerks. The device consisted of large wooden cabinets along with two or three viewing scopes. It made it easy for shoe clerks to identify how well a shoe would fit on a customer’s foot, especially the foot of a child, whose feet were ever-growing. The idea was that the device would help prevent the customer from buying shoes that would damage their feet due to a poor fit.

The device became extremely popular, to the point that over 10,000 units were sold to shoe stores throughout the country. However, these devices exposed the feet to high doses of radiation that were ultimately deemed unsafe. More and more reports came out detailing incidents of skin burns as well as issues regarding the stunting of bone cartilage. By 1970, the device was banned in 33 states. Soon after, it was banned country-wide.

Hair Removal

One of the common side effects reported by researchers in the early days of X-ray research was the loss of hair. Beauticians and physicians alike saw the benefits of such a side effect as a way to remove superfluous hair. In particular, Albert C. Geyser began training beauticians in the use of X-ray machines and then leasing devices to them for use in salons throughout the country.

Beauticians used their X-ray devices to expose their customers to four-minute long doses of X-rays to their faces. While it certainly removed hair as advertised, it also resulted in numerous other side effects, including wrinkling, keratoses, atrophy, ulcerations, carcinoma, and in some cases, even death. Bad press effectively banned the device before the FDA had a chance to officially do so.

Unfortunately, the consequences were already severe. It’s estimated that there were thousands of victims, many of whom developed cancerous growths and tumors. One study estimated that in 1970 more than a third of all radiation-induced cancer found in women over a 46-year period could be traced back to X-ray hair removal procedures.


The X-ray microscope functions similarly to that of a normal microscope albeit with the use of X-rays. The first X-ray microscope was invented by Ellis Coslett and William Nixon in 1951. The X-ray microscope allows researchers to examine the hidden structures in things like wood, metal, rock, bone, teeth, and ores.

Unlike the ill-fated shoe-fitting fluoroscope and hair removal device, the X-ray microscope continues to be relevant today. Recently, more powerful X-ray microscopes have been created that provide higher resolution images allowing for the study of biological specimens, geological samples, and more.

Airport Security and Border Control

Due to the ability of an X-ray to penetrate through objects, it’s become incredibly useful as a tool for security purposes. X-rays are used every day to improve security at airports and along border crossings. This is because they allow guards to see what people are carrying with them to determine if there’s anything illegal or dangerous on their person or in their luggage.

Airports use a conveyor belt system to scan luggage through a large X-ray machine. Security personnel carefully evaluate the X-ray images produced of each item to identify anything that might be dangerous, hazardous, or illegal before allowing the passenger to collect their luggage and head to their boarding gate.

Border agents use larger X-ray machines at border crossings to scan entire vehicles. There has been some controversy over the use of these X-ray machines since they do use a larger dose of radiation to develop images of entire vehicles.


Scientists discovered that the sun produces X-rays as early as the 1940s. However, in 1962, the first cosmic X-ray source was discovered. Dubbed “Scorpius X-1,” the X-ray source is not only the strongest known X-ray source in space, it’s an estimated 9,000 light years away from Earth. This discovery resulted in the field of X-ray astronomy.

X-ray astronomy is a field concerned with X-ray observation and detection from astronomical objects. There are thousands of X-ray sources throughout space that have been discovered since Scorpius X-1. However, because X-rays are absorbed by the earth’s atmosphere, instruments built to detect X-rays must be taken to a high altitude in order to function. This is accomplished through the use of sounding rockets, balloons, and satellites. Specialized telescopes that use X-ray radiation allow researchers to see much farther than with standard telescopes, which function using regular light absorption methods.

Looking Towards The Future

The discovery of the X-ray has allowed for some incredible scientific advancements over the years in many different fields, most notably within the healthcare industry. Although X-rays can be dangerous due to their radioactive nature, researchers have found ways to reduce the doses to a harmless level so that they do not cause negative side effects.

The use of X-rays has been around for over a century, yet advancements are still being made using X-ray technology. For example, a few years ago researchers in Singapore and at MIT discovered that a sheet of graphene (a 2-D form of pure carbon) can be used to create plasmons (surface waves) when struck by the photons of a laser beam, which in turn could generate a sharp pulse of radiation.

The discovery could allow for much smaller X-ray machines to be built that would produce the kind of beams that current machines can only produce using enormous and costly particle accelerators. The discovery could also allow for more precise X-ray images as well as lower doses, making them safer and more effective.

As advancements such as these continue to be made, it’s likely that it will lead to even more scientific discoveries in numerous fields, especially in observational astronomy and the healthcare industry.