Ionising radiation: Examples

​When we talk about ionizing radiation, you may at first think about radiation from nuclear power plants and other places with radioactive substances. But there are other kinds of ionizing radiation that doesn't come from radioactive decay. X-rays, for example. That's a form of electromagnetic radiation just like gamma radiation. But there's less energy in the X-rays.

If you have come across an electromagnetic spectrum before you'll recognize this. Gamma radiation has the highest frequency, the shortest wavelength, and the most energy. Gamma radiation is also the most ionizing. X-rays have a somewhat greater wavelength and less energy. X-rays can be created without the use of any radioactive substances at all. ​ ​Inside a tube of glass, a strong electrical voltage is created.

From the negative end electrons are shot at a metallic plate. When the electrons smash into the atoms of the metal plate at high speed, energy is released in the form of x-rays which are emitted out of the glass tube. X-rays have a very useful property. They can partially go through the matter that they run into. In hospitals, this property is used to see the inside of the human body.

Radiation is sent from an x-ray tube into the body. On it's way through the body the radiation is almost completely stopped by the bones, while more of it passes through muscles and other soft parts. On the other side of the body, there is a sensor that registers how much of the radiation has got through. The result is an image where different tissues are clearly visible. X-rays are stopped by a thin layer of lead.

Sometimes when a patient is being x-rayed, special lead aprons are used to protect the nurse and the patients body parts that don't need to be x-rayed. ​ ​Further down in the electromagnetic spectrum after x-rays, there's the ultraviolet light- UV light. UV light is a part of the normal sunlight that reaches us from the sun through the atmosphere. It's those rays of UV light that make the skin turn darker if you spend time in the sun and get sun tanned. UV light is an ionizing radiation too and even if it is weaker than both gamma radiation and x-rays, an exposure to UV light also increases the risk of cancer. But there's no need for a layer of lead to stop the UV light.

Normal clothes and some skin lotions protect the skin from the ionizing UV radiation. ​ ​It's not just UV light that bathes us in radiation. We are constantly being bombarded with ionizing radiation from the surroundings. Some of it comes from space. Most of the ionizing radiation from space is filtered out by the atmosphere. But some of it reaches Earth, and us.

When traveling in an airplane, high up in the air, the dose is higher. But you need to fly very often for that to matter. ​ ​Radiation that is always there, either from radioactive materials or from other sources, is called background radiation. Because of the background radiation, sunlight, and visits to hospitals, we are constantly exposed to ionizing radiation without being injured. Because it's the dose - how much radiation we are exposed to - that matters. ​ ​Everything in moderation, even radiation. But when it comes to radiation, a moderate amount is very little.