How does radiotherapy work?

How does radiotherapy work?

To better understand how radiotherapy works we should first look a little more in depth. Radiation is the propagation of energy and once that energy reaches any given material, it interacts with the material’s molecules through energy exchanges. These energy exchanges may occur in different amounts, depending on the quantity of energy being traded and the type of radiation involved. 

In our daily lives we interact with radiation all time. The sun’s being the most obvious, but also when using our cell phones, microwave ovens or even the television remote. From here it is easy to see that not all radiation looks alike, one of the most important aspects being the capacity to change the material with which interacts. At molecular level, if a kind of radiation trades enough energy to eject at least one electron from the atom, it’s called ionizing radiation. This means that such a kind of radiation is strong enough to induce damage and is the kind of radiation used in radiotherapy to treat cancer patients. 

How does it work?

Being the radiotherapy’s objective to kill the cancer cells, let me take you in a microscopic tour inside of a single tumoral cell. As the radiation reaches it, energy starts to be traded with all the different cell components, but we will focus on just two. 

Let’s investigate DNA. This complex molecule lives inside the nucleus, and it is responsible to guide all of the different functions that a cell needs to survive, including making repairs and reproducing. A tumours growth is via a complex group of cells that have lost the ability to repair and control reproduction. So, when radiation starts to interact with the cell DNA, it ionizes the molecule, leaving it damaged. This damage can be of different kinds (one broken strand, both broken strands, base shifts…) all of them with different implications for the cell’s survival. These are called direct action hits.

Now shift your attention to a less impressive, but no less important thing. Water. The insides of a cell are composed mainly by it and a remarkable thing happens when radiation interacts with it. Our H2O molecules are also affected by radiation, and they tend to break in a rather ominous components called Oxygen free radicals. These are highly reactive, and they tend to destroy much of what they get in touch with, including DNA. Once these radicals hit DNA, they leave behind the same kind of damages that radiation does by itself. These are called indirect action hits.

Let’s step out of the cell and look at a wider image. If we could see the many cancer cells being struck by radiation, we would see a chaotic environment. But once the radiation stops, an impressive number of resources are mobilized within a cell to try and repair most of these damages. That’s right! The cells often survive, and this is absolutely normal. All the cells in our bodies are used to take damage from a variety of sources and are pretty routine on making repairs.

What does that mean for radiotherapy treatments?

In fact, that’s one of the reasons why radiotherapy treatments are made on several sessions. By administering small doses of radiation over a period, the cells will accumulate a significant number of damages, enough to derail the repair process and thus triggering cell death. Also, cell sensitivity may differ over time due to many factors and by splitting the treatment over a period of time it is more likely to be successful.

Why don’t we administer all the dose at once?

There are some radiotherapy treatments that can be done in such a way, but the vast majority of it can’t be due to a simple reason. Remember that when radiation beams are used, healthy tissue cells will also be irradiated and accumulate damage causing side effects. 

What about healthcare staff? 

Since radiation has the capacity to induce these changes in our bodies, it is imperative that only the person who actually needs the treatment is irradiated. For radiotherapy medical staff is of outmost importance that treatment rooms are completely shielded to avoid any long-term health complications related to their jobs. 

So, if you are planning a new installation or planning to upgrade equipment and need your treatment vault assessed, check out our different services and reach out. Here’s how. 

André Pereira


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