ELi5: What does medical radiation do to the body?

255 viewsBiologyOther

I have breast cancer and I’m starting radiation tomorrow. I understand that it’s supposed to reduce the risk of reoccurrence and that it is destroying cells. But how? Which cells are affected? Why will it make me tired?

In: Biology

18 Answers

Anonymous 0 Comments

Your doctor is going to be a better resource than Reddit. Radiation is like a hail of tiny bullets passing through the body – smaller than even atoms. It will hit and break apart molecules on its path. Since your cells’ machinery is mostly individual molecules, the pummeling from radiation can do enough damage to kill the cell.

Even if the cell survives, it will have repair work to do. This can be pretty costly, biologically, so when swaths of your body are exposed to radiation it can leave you exhausted as you recover.

The radiation is fired through many paths. Each path passes through different healthy cells, but they all converge on the cancerous area. The result is healthy cells getting a small dose – mostly just needing repairs – while the bad cells get a huge dose and die.

Anonymous 0 Comments

The short and misleading answer is that every cell in the beam path is affected.

But the thing that makes cancer cells dangerous is also their weakness: they’re always dividing, which means when their DNA gets damaged by radiation, they don’t have time to stop and repair it. Your healthy cells will get hurt by the radiation but they’re much better at recovering from it, so that’s a tough call to make but years of research show it’s the course with the most happy endings.

The fatigue is partly from that recovery thing – you’ll spend a surprising amount of resources as damaged cells repair themselves – not much you can do about that except grit your teeth and get through it. In some cases the radiation can also disable bone marrow and lead to anemia, which causes fatigue too. If you get put on iron supplements, that’ll be why. (Edit: a radiation beam through your boob will probably only hit your ribs and they’re mostly yellow marrow, so with my zero years of medical experience I’m going to say radiation anemia is unlikely here…?)

The treatment’s no fun, but remind yourself: as tough as it is on you, it’s far worse for the cancer. Take naps. Good luck. <3

Anonymous 0 Comments

> But how? 

Like radiation usually does: blows bits off of DNA and other organelles until the cell stops working.

> Which cells are affected

Everything in a straight line through the body from the radiation source, scaling with time spent in the path of the beam. The art in using radiation treatment is moving the emitter around the body so most cells only get hit for a short time while the cancerous area is constantly lit up.

> Why will it make me tired? 

Repairing radiation damage takes resources.

Anonymous 0 Comments

Quick recap on what ionizing radiation does. When electrons absorb an electromagnetic wave, they move up into a higher energy state, which is kind of like a higher “orbit” around the nucleus of its atom. Ionizing radiation gives electrons so much energy that they can fly off the atom entirely. Atoms bond into molecules by sharing and trading electrons, so if you suddenly knock an electron off, it can really screw up that molecule. Plus, atoms really want to be electrically neutral, so if an atom loses an electron it will try to take one from another atom and end up either ripping the electron away (screwing up that molecule) or bonding into the molecule (also screwing it up). Other forms of ionizing radiation are alpha particles (which are basically helium nuclei going *really* damn fast) and beta particles (which are electrons and positrons – which are the antimatter version of electrons, exactly the same but with the opposite electric charge – going really damn fast).

DNA is *really* sensitive to these sorts of changes because it’s just such a huge molecule. There are many opportunities to absorb radiation, and even small changes in the bonds between atoms can really screw up the whole molecule. This is why ionizing radiation is dangerous and can lead to cancer – your DNA gets damaged so that the cell’s instructions on when to die and how often to reproduce get messed up, so it doesn’t die and reproduces way too much. That’s very unusual, though. Most of the time, damage to DNA either isn’t enough to do anything at all; or, the damage is so severe that the cell can’t function and dies; or, various safety features built into your DNA cause the cell to notice that it’s damaged and it self-destructs or gets killed by an immune cell. It’s rare that the damage is *just right* to cause cancer. Unfortunately for us, we have a *lot* of cells so even if it’s rare, there are so many opportunities for it to happen that we end up with cancer.

What radiation therapy is trying to do, then, is apply a high dose of radiation targeting only the cancerous cells and tear up their DNA so much that they can’t function anymore and just die. Nothing is perfect, of course, and the radiation can and probably will damage nearby healthy cells. It will even increase the risk of cancer in those cells. But think about it this way: what’s the worst thing that could happen, you get cancer next to your cancer? The benefit – hopefully killing off the existing cancerous tissue – is worth the risk. And, the radiation therapy will be as targeted as possible so that most of the affected cells are the cancerous cells and the surrounding healthy tissue won’t be too affected.

There are a few ways of targeting the tissue. One way is to create a sort of “laser” of positron radiation and aim it at the cancer. The positrons will have enough energy to penetrate into your body to reach the cancer. From there, the positrons will combine and annihilate with electrons (as matter and antimatter do), which creates some high energy gamma rays. Between the positrons annihilating electrons and the gamma rays knocking them around, the DNA should get properly shredded and the cancer cells will die. They may insert a tiny radioactive pellet that spits out alpha rays. Alpha rays will knock atoms and electrons around around, but they can’t penetrate through a thick sheet of paper, much less deeply into your body. That’s why they have to surgically insert the source into the middle of the tumor; but, since it doesn’t penetrate very far, it won’t affect tissue away from the tumor. They may also just use a beam of X-rays or gamma rays, pointed at the cancer.

It makes you tired because it’s killing off a bunch of cells, both healthy and unhealthy. Your body has to repair the damage and clean up the dead tissue, which takes energy just like any other injury. Depending on where the cancer is, it could be really messing up the function of an important organ which needs to be repaired. Again, the damage is worth it because you’re killing off much more dangerous cancer. Regardless, fixing that requires a lot of effort from your body.

Anonymous 0 Comments

I’m so sorry for your diagnosis. Make sure you’re clarifying this info with your doctor and also nurse navigator if you’re lucky to have one! Skin care is imperative, and take the side effects of radiatikn seriously. Good luck to you!

Anonymous 0 Comments

Ionizing radiation does exactly that: it removes electrons from atoms and creates ions. This means that molecules (which are atoms held together by sharing electrons), are broken apart.

Since all our cells are just giant collections of molecules, knocking electrons off breaks apart critical items like proteins. There are different forms of ionizing radiation: photons (gamma rays, x-rays), neutrons, alpha particles etc. Think of them as bullets flying around that hit chains, breaking links.

As to why it makes you tired, I can’t say. It must damage certain tissues that are involved in processes that regulate how much energy you have.

Anonymous 0 Comments

If you’re doing radiation / chemo you will be tired. Your body is working to heal itself and needs the energy. Most importantly though is giving your body the fuel it needs.

You’re going to be nauseous / nauseated. Eat as much calorie dense foods as possible. Find foods that your stomach will tolerate. Don’t make yourself worse, just eat as much as you’re able. Your body needs that energy to keep fighting. If your body is calorie deficient it can’t fight.

Best wishes on your recovery.

Anonymous 0 Comments

I have had radiation therapy for prostate cancer – they used a radiotherapy machine that rotated as it sent a very narrow beam through me. The only bit that got continuous radiation was my prostate, everything else got a much-reduced dose.

It does knock you back, that can’t be denied. But play attention to what your medical advisors tell you regarding diet, exercise, medicine, etc. Don’t neglect anything, just do what they recommend. They’ve seen so many cases like yours and have a very good idea of what helps recovery.

Very best wishes for the future.

Anonymous 0 Comments

As a radiotherapist of 15 years you’ll be fine. The long and short of it as has been said is the beam will damage the whole breast but the cancer cells won’t recover but your healthy tissue will. You may feel tired as the healthy tissue recovers and the mental load of going through cancer treatment can take it out of you, but with modern treatments it’s not that likely to cause issues. In all likelihood the radiographers will go over everything before you have any treatment, we’re used to any and all questions you might have and don’t feel like anything is a dumb question we’d feel much worse if you didn’t ask.

Anonymous 0 Comments

Radiation, like platinum-based chemotherapy drugs create jumbles and breaks in the DNA of all the affected cells. Tumors, however, tend to have 2 characteristics: they replicate/multiply very fast, and they are not very good at repairing damage in their DNA.

When a cell (healthy or cancer) divides, it needs to copy its entire DNA. If it finds damages, it needs to be repaired. If the damage is too big and widespread that it cannot be repaired, the cell commits suicide.

Cancer cells divide very fast, so they’ll have to face these damages early and make a “decision”: repair or die. Healthy cells don’t divide that fast and they have more time to repair their DNA back to fuctional levels.

This is also the reason why your skin, stomach, and all kind of mucosas of the body are harmed by chemo. Because they replicate faster than other cells/organs.