Eli5 How does radiation therapy actually work? Like how doesnt it break down more of the body and make the cancer worse or something like that? And does it target only cancer area or everything?

Question

Eli5 How does radiation therapy actually work? Like how doesnt it break down more of the body and make the cancer worse or something like that? And does it target only cancer area or everything?

In: 630

Answer 1

Imagine you’re talking down the street, and you look through the window of your neighbor’s house and you see that their kitchen stove is on fire. The fire department shows up, and is tying to come up with a plan to deal with the fire.

There’s a couple of things they can do with the tools they have

1. They can break down the front door with an axe, tear the stove out, and chop the power line to it, and throw it out. The problem here is a broken door, some other collateral damage to the kitchen like the cabinets or other appliances. And since they just tore out the stove instead of putting out the fire, maybe there was something else on fire that they didn’t notice
2. They can activate the sprinkler system. The stove fire will definitely be put out, but everywhere in the house will get wet. The longer the sprinklers are on/the longer it takes to douse the stove, the more stuff in more rooms will get waterlogged and ruined.
3. They can smash a window, and point a fire extinguisher at the stove and let loose. They’re aiming primarily at the stove, but anything in the direct line of fire in front of the stove (the window, the rug, maybe a chair, will also get at least a little gunked up. And if they miss, something else will get really gunked up and the fire won’t be out.

The Axe is surgery.

The Sprinkler is chemotherapy.

The Fire Extinguisher is radiation.

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With radiotherapy, the goal is to deposit most of the energy from the beam into the cancer cells, and only the cancer cells. You don’t want to miss and ruin something else, so they take very detailed scans/images and come up with a very precise plan in advance. But hitting some stuff on the way in (for example, skin or muscle), is hard to avoid. So one way to deal with this is to take the shots from a bunch of different angles over a bunch of different low-dose sessions. That way, the only thing that gets a high cumulative dose is the cancer.