There are many perception out there on the risk of radiation. Many people believe radiation to be extremely harmful to their health. But are these perception of the risk of radiation warranted?


First off, we are specifically talking about ionizing radiation here. We are not discussing the risk of cell phone radiation, you can read about that here. And besides, there is no need to worry about cell phone radiation.


If you are not familiar with the distinctions between ionizing and non-ionizing radiation it would be best to read this articles.


So let’s start off by looking at setting a few facts straight about the risk of radiation


What is radiation?


Radiation is best explained as energy moving through space. It can come in many forms including visible lights, mobile phone electromagnetic radiation, x-rays, gamma rays, microwaves, and radio waves. These are all the same type of radiation. They are all electromagnetic radiation.


There are also high energy particle radiation, these include electrons, protons, and neutrons.


Now you need to know the difference between ionizing and non-ionizing radiation. Ionizing radiation is radiation with a high amount of energy. This includes x-rays, gamma rays, part of the ultraviolet spectrum, and high energy particle radiation.


Microwaves, radio waves, and visible light are non-ionizing radiation. That is they don’t have enough energy to ionize stuff.


Radiologist and Radiation oncologists use the properties of ionizing radiation in medicine. Radiologists use low dose radiation in the form of x-rays to form images of the body. Think chest x-ray or CT/ CAT scans. Radiation oncologists use high dose radiation targeted at cancers to treat them.

What are x-rays?


X-rays are the main type of radiation used in medical imaging and treatments. They are high energy electromagnetic radiation.


X-rays are used in medical imaging in a similar way in which your camera on you phone uses light to create an image. The difference being the x-rays travel through your body and create an image off the different densities inside your body.


Most people will refer to the image created as an x-ray images, but the x-rays are actually the radiation used to produce the image. It’s similar to calling a photo a light-image, the light is use to create the image, it is not the image itself.


Where does radiation come from?



Radiation generally radiates from a point source, one location, when humans create it. But radiation is all around us in nature. This is called background radiation.


The sources of natural background radiation include the sun in the form of cosmic rays, the earth, in the form of radioactive elements in the rock, and from our bodies, through radioactive decay of elements we eat and breath


The other source of radiation that you may encounter is medical radiation through CT scans and dental x-rays.


That leaves us with two sources of radiation you may be exposed to. There is natural background radiation, and there is medical radiation.  So how much radiation from each source does someone of average receive.


To measure the amount of radiation someone receives we need a unit of measurement. Radiation is measured in millisieverts, or mSv for short. The amount of background radiation varies around the world but you can expect to get around 2-3 mSv per year of background radiation.


The amount of medical radiation you receive also varies around the world, depending on your access to medical imaging and how frequently these devices are used. If you live in the us you can expect to get another 2-3 mSv per year of medical imaging dose.


How much radiation do I receive


Below is a list of typical medical radiation procedures and how much radiation you can expect from each. There are also other sources of radiation listed, such as natural background radiation and the radiation you receive when traveling internationally on a plane.

  • Dental X-ray 0.01mSv
  • Airline flight 0.02mSv
  • Mammogram 0.04mSv
  • Chest X-ray 0.10mSv
  • Natural Background radiation 3.1mSv/year
  • Average US medical exposure 6.2mSv/year
  • Chest CT scan 7.0mSv
  • Abdominal CT scan 8.0mSv



Understanding your risk


OK, so now you know how much radiation you receive from different medical tests and from background source. But what is the risk involved with the amounts of radiation in each?


It is important to realize that the medical community has been trained to only use radiation when there is a benefit to your health that outweighs the risk. Great effort has been made to ensure that you receive the least amount of radiation necessary without compromising the results of your medical examination.


This is because data from studies has shown that a high dose of radiation increases your future risk of cancer. The risk associated from low dose of radiation is still being debated, but we assume that any amount of radiation increase your risk slightly.


This data has come from survivors of the atomic bombs and other radiation accidents and incidents.



The Banana scale


The internet produces wonderful things. One of the best ways to relate medical x-rays and radiotherapy to something we know well is the banana scale. There is a natural amount of radioactive isotopes inside bananas. This means that….


Bananas are radioactive.


Although this does not mean you should stop eating them, the amounts are low and are included in your natural background radiation. This does mean that you can relate different medical exposures to an equivalent amount of bananas.


So theoretically to receive the equivalent amount of radiation from these image procedures you would need to consume the number of bananas stated.


  • Living next to a nuclear power station 1-100 bananas
  • Dental X-ray 50 bananas
  • Average daily background radiation 100 bananas
  • International long haul flight 400 bananas
  • Living in a stone/concrete/brick building 700 bananas
  • Chest x-ray 200-1000 bananas
  • Mammogram 20000 bananas
  • Chest x-ray 70000 bananas
  • Radiotherapy treatment 20000000 bananas
  • Fatal dose of radiation 100000000 bananas


That’s a lot of bananas to receive an equivalent dose of radiation. Would be great for the country of Ecuador!




It is important to understand the risks associated with medical radiation. But in doing so, you must understand that your medical professional will have weight the potential benefits and risk and only recommended the exam if the benefits outweighed the risks.


Understanding the amount of radiation you will receive from a certain medical examination is difficult since most people have no idea what radiation is measured in and how to related it to everyday items. Using the banana scale is great in being able to explain the risk in terms that people will understand.