What is the difference between the types of radiation that cause cancer and the types of radiation used to treat cancer?
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First of all, you need to understand the basics of radiation. There are three main types:
1. Alpha particles
2. Beta particles
3. Gamma rays
Alpha particles are just 2 protons and 2 neutrons. It is the same structure as the nucleus of a Helium atom (specifically Helium-4). This is the weakest of the radiation types and can be blocked by a sheet of paper, or even clothing and skin. It can really only harm you if it gets inside your body through inhalation or ingestion.
Beta particles are simply high-energy electrons (or their anti-matter counterpart, positrons). They have a bit more energy than alpha particles and require a thin layer of lead or concrete to stop them.
Gamma rays are high-energy photons… in other words, they are just light. Light starts to become ionizing once it gets into the ultraviolet range. Gamma rays are far more energetic. So much so that they would very likely pass through you as if you weren’t even there.
Very quickly, I will mention neutron radiation. Free neutrons are unstable and will decay in about 15 minutes. They are only produced by fission and fusion reactions. While they can be extremely harmful to us, the only way you would be exposed to them is by proximity to fission or fusion processes, in which case you’ve got much bigger problems than neutron radiation.
Ok, so here’s a fun little thought experiment–I will give you three cookies: one has a small quantity of alpha particles emitting substance baked inside, the second is made with beta particles, and the third is made with gamma rays. You have three options: eat the cookie, sit on the cookie, or throw the cookie out the window. BUT you can only use an option one time. So… what do you do?
The correct answer is that you eat the cookie with gamma rays, sit on the cookie with alpha particles, and throw the beta particle cookie out the window. You see, just like a bullet, damage is done if your body absorbs the energy. So, if you eat the alpha particle cookie, you body will absorb 100% of that energy. If you eat the beta particle cookie, you will absorb about 50% of that energy (the rest will pass right through you). And the vast majority of gamma rays will exit your body as if you’re not even there, so the energy absorption is very low. If you sit on the alpha particle cookie, you clothing and skin will block nearly 100% of the energy. With the beta particle cookie, however, your body will still absorb nearly 50% of the energy if you’re sitting on it, so you want that one as far away from you as possible.
As for radiation treatment, there are two general types: external and internet. External treatment uses high-energy photons in the form of x-rays (lower energy than gamma rays, so they will absorb a bit more into your body) which can be targeted to a specific tumor. However, as mention above, these high-energy photons will largely pass through the body without hitting anything, so you need a lot of them to get the job done. And, of course, they can and will damage any non-tumorous cells that are in the line of fire.
For internal treatment, they identify which substances (usually some type of hormone) will bind to the cancer cells. Then, it’s just a matter of mixing that substance with a small amount of a radioactive material that produces mostly alpha particles. Here again, other non-tumor cells will be destroyed in the process, but the goal is to destroy as many of the cancer cells while mitigating collateral damage to the the healthy cells.
This also give you some insight into why the “stage 4” or metastasis phase of cancer is so often terminal. At the this point, the cancer cells have “metastasized” or spread throughout the body. If you were to try radiation treatment (or pretty much any other treatment) at this point, it would do more damage to the person than they could recover from, and still not get all of the cancer cells.
I know this was pretty long, but hopefully it gives you a better understanding of radiation and how it works.
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