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The Inside Scoop on Calgary X-ray Services


Many people wonder how x-rays work. In fact the very name "x-rays" came from the fact that the mechanics of the form of radiation was unknown when it was first discovered. X-rays are a type of electro-magnetic radiation. The wavelength is slightly shorter than that of ultraviolet light. It measures 10 to 0.001 nanometers.

The history of x-rays

German professor of physics, Wilhelm Rontgen is credited with the discovery of x-rays. His work in 1895 which brought about the development of today's x-ray imaging was not a matter of research, but appears to have been an accident. Professor Rontgen was conducting an early experiment with a light-emitting tube known as the Crookes tube. In the course of the experiment, it was noted that fluorescence was present in a nearby screen, in spite of a cardboard surround for the Crookes tube.

Because it was apparent that some unknown light source must have been passing through the cardboard, the professor conducted other experiments. He found that the unknown radiation or x-ray could pass through other materials as well. One of the materials that were rendered invisible by x-rays was human flesh. Imaging became the primary application of this form of radiation. The first x-ray was the image of the hand of Mrs. Rontgen.

How does the x-ray image occur?

The photons (a group of electromagnetic energy) that makes up an x-ray are very high energy, higher than visible light that can be registered by the human eyes. The high energy and short wavelength are part how radiation operates. In simple terms, an x-ray is generated when a cathode (an electrode through which electrons move) is heated to a high temperature so that electrons escape from the cathode and are attracted to the anode on the other end of the vacuum tube. High velocity impact with a tungsten anode releases an x-ray photon. Because the entire tube has only a very narrow opening which is unshielded, the photons escape in a concentrated beam into space.

The beam travels through space easily. It also passes through soft tissue, because soft tissue cannot absorb the ray at high energy levels. When more dense material, such as calcium which makes up bone formation, is encountered, it does absorb the radiation. Beyond the part of the body that is being photographed is the film. It works in a way that is similar to any film. The photons that pass through soft tissue appear as black images when exposed on the film. The white areas on the film are unexposed. This unexposed portion is because photons are absorbed by the bone or cartilage which is denser.

What is the protocol for obtaining images?

When a patient needs to have an image taken of some part of the body, the technician has the responsibility for properly arranging the part of interest between the film and the machine which captures the image. The image that is captured is only two dimensions. There must be shielding for any areas which are not in question. Once the image is captured, it is reviewed by the radiologist. Today's technology allows for a transfer of images to a computer monitor. There is no longer a need for physical film.


CDC is an industry leader for walk-in x-ray examinations. For more information on our x-ray services please visit our general x-ray information page or to book your next appointment please find a CDC x-ray clinic nearest you.