How Are X-Rays Produced?

April 7, 2020 – 5 min read

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image of a man's hands holding an image of a chest x-ray

Although X-rays are now associated with doctors’ offices and technical medical professions, their discovery was surprisingly an accident. In addition to this tidbit of trivia, X-rays have a long, illustrious history and are still extremely relevant to medical innovation today.

In this article, we’ll review how X-rays work, how they were discovered, and how their history lives on today in their many important uses in the medical imaging and diagnostic industries.

The Science: How X-Rays Work

X-rays are classified in scientific terms as a kind of electromagnetic radiation. In terms of behavior and structure, these X-rays are comparable to those of visible light. However, X-rays have a higher energy concentration than the wattage of a light bulb — so high, in fact, that their photons can literally pass through objects.

If there is no receiver to reflect or absorb the X-rays, not much will happen other than radiation exposure. But when it comes to medical imaging and diagnostic X-rays — today’s primary use for the rays — an X-ray detector is placed on the opposite side of the light source; this detector produces the images of whatever “shadows” of substance the X-rays are able to identify on the inside of an object or body. These images are called radiographs.

Different types of tissue in the body (or different layers of any object) have varying atomic structures and compositions, so X-ray waves will be absorbed and transmitted in ways that reflect these features. For instance, when X-ray imagery is used to see and diagnose the state of a bone, the high-calcium composition of the ossic material (which also has a higher atomic number than other tissues in the body) allows the bones to absorb more X-ray light energy than, say, the skin would. This is why bones are so much easier to see on X-ray-produced images, as opposed to more “invisible” structures like lungs, fat cells, and muscle tissues.

The History: How X-Rays Were Discovered

As mentioned in the introduction of this article, X-rays were discovered not after years of intentional research for their isolation, but rather by a fortunate accident.

More than 120 years ago, back in 1895, a German physicist named Wilhelm Roentgen was studying the behavior of electricity in a vacuum. In order to create this environmental condition of the test tubes, Roentgen would remove as much oxygen and air from the vessels as possible. Inside of a vacuum such as this, electrons move much faster than they do in our natural atmosphere, which is obstructed by various kinds of molecular debris.

This is all well and good, but the discovery happened when the electrons began behaving rather strangely. These little subatomic particles collided with both the cathode and the anode areas of the test tube, bouncing back and forth and bumping into each other as well. Roentgen observed a strange light emanating from the anodic end of the tube, and soon realized it was a section of the light spectrum that hadn’t yet been discovered. This would come to be known as the X-ray.

The brainy German was unimpressed at first by the light, but quickly changed his mind when he saw that a fluorescent screen in his lab, obstructed by a heavy piece of cardboard, was glowing in response to the light coming from the anode. Typically, the light sources in his lab would not be powerful enough to activate fluorescence; the receiving object was covered, so Roentgen realized he must be dealing with a more powerful variety of energetic waves.

Ever the curious physicist, Roentgen incrementally tested the intensity of the light. Eventually, he determined that no object in his lab could be used to block the electronic-based light or to stop the fluorescent screen from glowing. Indeed, when moving various objects between the test tube and the screen, at one point his hand passed in front of the light stream — and was rightfully shocked to see a shadowy outline of his bones!

The Application: How X-Rays Help Doctors

Once Roentgen (accidentally) discovered the superhuman vision powers of X-rays, it wasn’t long before the medical industry realized its practical applications.

Today, there is an entire medical specialty centered around the use of X-rays and medical imaging technology referred to as radiology. Medical x-rays may be used for diagnostic or therapeutic purposes.

Diagnostic X-rays can produce images of bones (healthy, broken, or fractured), abnormal growths and tumors, calcification such as kidney stones, caries and decay of the teeth, and even pulmonary issues like pneumonia. Diagnostic X-rays are also regularly used in mammography (detection and diagnosis of cancer in breast tissue), CT scans (multiple X-rays that produce a more detailed cross-sectional image), and fluoroscopy (a sort of real-time, moving image).

Therapeutic X-rays, on the other hand, refer to the treatment of cancer by way of radiation therapy. This may also be used with or independently from chemotherapy; depending on the severity of the cancer, radiotherapy alone may be adequately effective. Essentially, the minute and targeted amounts of radioactive material given off by X-rays are precise enough to kill the cells affected by cancer, but not so intense that the surrounding tissue and organic matter is injured or compromised. For cancerous tumors that have not metastasized, therapeutic X-rays can be a highly effective treatment option.


X-ray imaging is a fascinating form of medical imagery with a history as interesting as its modern applications in treatment and diagnosis. To think that such an impactful scientific process was born out of simple tinkering is perhaps the most intriguing piece of trivia about this technology.

To learn more about the useful applications of X-rays, CT scans, ultrasounds, and more, please reach out to Touchstone Medical Imaging today.