How does proton radiation therapy work?

I’ve made lots of videos on tons of topics, covering the quarks to the cosmos, so to speak. In this.

I’ve made lots of videos on tons of topics,
covering the quarks to the cosmos, so to speak. In this video, I thought I’d tell you something
that is way more down to Earth. I thought I’d tell you about something about
a specific kind of radiation therapy, called proton radiation therapy. Now before I do that, I should remind you
that I am not a doctor. Well, I am, but as my somewhat curmudgeonly
aunt Margaret will often remind me- Not the kind of doctor that’s good for anything. Personally, I think that’s a bit unfair,
because physics is at least as cool as medicine, but she does have a point. I’m not an M.D. Oh yeah- goodbye, Aunt Margaret! So don’t think that I am offering useful
medical advice, because I’m not. And I’m probably too expensive for you anyway. Now I don’t want to make light of cancer. It’s a serious thing. I’ve lost people I care about to it. And when we’re talking about it in a real
world situation, it’s very, very, very complicated. But since I’m not the useful kind of doctor,
I can simplify things. Depending on whether a cancer is localized
or spread out and intermixed with ordinary tissue, the real kinds of doctors will operate
to try to remove the tumor or do chemotherapy or maybe use radiation to try to kill the
tumor. So let’s talk about the radiation option. Traditionally, doctors used gamma radiation
to try to kill the tumor. I made a video on the various kinds of radiation
if you’re interested in what that means, but briefly, gamma rays have no electrical
charge and can penetrate deeply into the body. They’re like x-ray’s bigger and tougher
brother. Now, let’s suppose we have some sort of
tumor that is small and compact- say the size of a marble or so. Let’s also say that it is buried deep inside
the brain. Because of its location, it might well be
inoperable. Chemotherapy might work, but if it is compact,
it might be amenable to using radiation therapy. So I’m going to talk about proton therapy,
but to understand why it is an interesting approach, I need to talk a little about conventional
radiation therapy and its limitations. So how does it work? Well, to begin with, conventional radiation
is emitted by the source of gamma radiation and hits the surface of your head. But what happens as the radiation passes through
the tissues of your head? The way it works is that the tissue near the
surface of your head gets the full rate of radiation and it absorbs some. As the beam goes deeper, the next layer also
absorbs some radiation, but less than the surface. That’s because the surface has already absorbed
a bit of it. When the beam arrives at the tumor, it has
already been partially absorbed by the layers closer to the surface. That means that the surface tissue gets more
damage than the tumor itself. And, of course, the beam doesn’t just stop
at the tumor. It continues on through the brain, and some
of it might even come out of the other side of your head. The brain tissue after the tumor gets a reduced
dose of radiation, but it still gets some. This picture really illustrates what’s going
on. The darker color means more radiation absorption. The healthy surface tissue gets the most dose
and therefore is most likely to be damaged. So that sounds kind of awful. The cancer only gets part of the radiation
dose and healthy tissue gets more than the cancer does. So how do doctors handle this? Well, the way they do that is they move you
or the beam so the beam goes through a different path through your head. That way, one treatment hits one spot on your
head’s surface, while the next treatment goes through another. However, every treatment goes through the
tumor. Over the course of multiple treatments, the
tumor gets hit again and again, with the other tissues getting hit only once. The goal is that the cumulative dose in the
tumor is higher than the other tissues receive. It’s actually quite clever. Now what about proton therapy? How does that work? Well, unlike gamma rays, protons have electrical
charge. They’re also heavy, at least as far as subatomic
particles go. And, when they pass through matter, they lose
their energy fairly slowly for most of the passage, but then lose a whole bunch just
at the end. This is called the Bragg peak if you want
to look it up. It’s kind of like when you’re slowing
your car down for a stop sign. It’s smooth going until the moment when
the car actually stops and then the back of the car settles down and you get a bit of
a jerk. We can see in this image what this means in
terms of energy dose. Here, the surface tissues receive a lower
dose than the tumor does and, further, the beam doesn’t continue on through the head. So this sounds like a great approach. And, of course you can do the trick of shooting
the beam at the tumor at different angles. This means it is possible to hit the deep
tumor hard, with much less damage to surrounding tissue. Now, proton therapy isn’t a new idea. The first paper on the subject was written
by Robert Wilson in 1946 when he was developing a cyclotron accelerator at Harvard. Robert Wilson also built Fermilab, the laboratory
at which I am a scientist. Wilson was like totally the bomb. The Harvard cyclotron collaborated with Massachusetts
General Hospital and developed the technology over the next 40 years or so. The first commercial and hospital-based facility
began in 1989 at the Clatterbridge Center for Oncology in the UK, followed by one at
the Loma Linda University Medical Center in 1990. That particular accelerator was built at my
own Fermilab and one of my fellow graduate students moved there to operate it. Small world. Proton therapy centers are becoming common
around the world. In fact, there’s one just a few miles from
Fermilab. I’ve even used it to irradiate electronics
to see if they would work in a high radiation environment. Now, I want to remind you that I’m not an
M.D. and I’m not a radiation therapy specialist. So don’t take any of what I’ve said as
medical advice. For that, you need to talk to a real oncologist
or a radiation expert; specifically, one of those kinds of doctors who actually is useful. Proton therapy is really pretty cool. It causes less damage to surrounding tissue
than conventional gamma ray radiation and it’s becoming useful to treat a variety of
tumors. While I hope that neither you nor anyone you
care about ever gets cancer, it unfortunately does happen sometimes. If you are in that awful situation, maybe
it makes sense to, like the television medical commercials say- Ask your doctor if proton therapy is right
for you. So like Aunt Margaret said, I’m not the
best source of medical advice, but the underlying physics is really super interesting. If you liked the video, be sure to like, subscribe
and share. Let’s get those numbers up. And let me know what you think in the comments. See you next time, and keep on physics-ing.

100 thoughts on “How does proton radiation therapy work?”

  1. Something weird is happening. Any motion (e.g., Dr. Lincoln's hands) seems to be exhibiting some kind of tearing. Anyone else observing this?

    EDIT: I'm watching the video in 1080p.

  2. I wonder if the criteria nowadays doctors use when they choose the best option for treating tumours is medical, physical or economic : (
    I mean, it seems to me this is far less harming to healthy tissue than gamma ray therapy… but, which hospitals can afford such an expensive machine? Which countries have at least one of these beasts?
    Interesting video, as always!

  3. Dear Dr Lincoln, Thanks for you practical info….. I will refer my patients to your video…very clear and concise. We use the proton beam a lot in our area to treat prostate cancer. Aunt Margaret was wrong; you are the "smarter" type of doctor. : )

  4. Radiation therapy was used to save my brother's life from a rare eye cancer by the brilliant folks at MGH. Thanks to everyone involved in developing revolutionary medicine to make our lives better 🙂

  5. With all due respect, Dr. Lincoln, there was way to much sarcasm towards medical doctors in this video. It seems like you consider MDs useless)))

  6. Awwww, you didn't answer the one question I wanted answered! If protons are in the nucleus, how the hell do they get them out for shooting into tissue? Did the actually split atoms? Or is there some fancy way of converting another, more easily available particle like an electron into a proton? Don't make me go to wikipedia!!!!!

  7. Doctor, the video is suffering from a lot of artifacting issues, I have tested it on multiple monitors and on my home TV. Unless Doc ascended to a higher Dimension without telling us, then the video is probably at fault. I have cross checked with previous video uploads, and it holds true (see Link for a quick preview). Please check. Best regards


  8. Could you fine people at Fermilab do a show on LFTR, Liquid Flouride Thorium Reactors, better known as MSR's Molten Salt Reactors.

  9. It's a pleasant change to hear something about real, evidence-based science rather than the pseudoscience of particle 'physics' and relativity. When lives are at stake, smoke and mirrors aren't enough.

  10. 3:52 I was just thinking that that would fix the problem… Not suprised they actually do it, as it sounded too perfect not to be the case.

  11. The diagnostician makes use of the fruits borne of a physicists' labours. I'm altogether reliant day-to-day, upon the imaging techniques unlocked by the natural philosophers.

  12. I have truly enjoyed all of your videos.
    And have always enjoyed science.
    Unfortunately my parents say I would blow up the house.
    So no science kits for me.
    I read and read and read
    Omni and old science digest…
    I saw the computer revolution coming.
    And had a good idea where it was going,
    Behold the Internet, I had checked out
    Books on quantum theory in the late 80's
    In a vain attempt to learn about it.
    And now we all have access to the worlds knowledge.
    From LIGO to CERN to super fluids
    And quantum fuzz, planks and the multiverse
    It is awesome, the kids today hold the wealth of the world in their hands.
    I might have missed my opportunity.
    But I can't stop learning about things
    That can no way benefit me…
    I guess I became the scientist I had wanted to be.

    Just not the good kind.

    But I know some, here and in the real world.
    To quote Spock, Fascinating…


  13. A different kind of work here for sure but as usual great. Keep them coming. Also, how about a video on identical particles. How can fields be so perfect to produce electrons identical including their charges. Something perfect producing perfect particles. That seems more unlikely than than being at the mercy of straying too much or little of the cosmological constant.

  14. But there was almost no detail on why proton beams are different. How is the fact that they have charge used? Why is there this Bragg bump? How does the beam know to stop just where the tumor is? This is the first time I've been disappointed by one of Dr Lincoln's videos. Follow up video please!

  15. I know how youtube therapy works, and a healthy dose of Fermilab videos prescribed by Dr. Lincoln is the medicine for science!

  16. Best to prevent cancer by eating whole food plant based diet, preferably organic foods where possible. Dont smoke. Dont drink alcohol. No meat, dairy, eggs, fish, oil, – no need for them at any stage in life.

  17. I read somewhere about inserting gold nano-particles into a tumor and hitting it with radio waves. Somehow it cooks the tumor. Do you have you any idea how that would work?

  18. Don't be too harsh on yourself, Doc. Without "not so useful" doctors, "useful" doctors couldn't be as "useful" by a long shot 😉

  19. Being both a "useless" physicist and a "real" doctor, I decided to work in proton therapy. I realized that one problem is that we do not know exactly where the Bragg peak occurs in the patient. Have been working on a solution of that problem.

  20. Please please please tell your camera men and post-production: QUIT SHOOTING AND EDITING INTERLACED VIDEO. This video is not 1080p. It's 1080i.

  21. A very interesting and informative video Dr. Lincoln. I would to know if the interesting tee/sweat can be purchased from Fermilab and if so, how does one order them. Thank you for your time.

  22. Excelente, me encanta el canal y cada uno de los vídeos que hacen. Solo un detalle, en el minuto 2:30, la máquina que sale ahí no es una fuente de radiación gamma, es un acelerador lineal que produce haces de rayos X de alta energía (MV), que también son utilizados en Radioterapia, incluso, hoy en día, se utilizan más que la radiación gamma. Cabe destacar que los aceleradores lineales también puede generar haces de electrones usados para tratamientos de lesiones más superficiales. ¡Saludos desde México!

  23. What happens then to the protons? Wouldn't they just build up in the patient body and cause damages? Because photons can just disappear but not protons. I guess one could fire electrons to cancel their charge but they would turn into hydrogen atoms which would be chemically super reactive wouldn't they? I mean I'm sure it shouldn't be that bad (or at least less bad than cancer itself) but I wonder how bad it is anyway.

  24. The first half of the video without getting to the point, and then two or three minutes of relevant information. 🙁

  25. This year, a friend of mine needed radiation therapy for the most malignant brain tumor known. He's doing fine for now, thanks to professional medics, AND scientists who paved the way. To say you're not a useful doctor is a grave underestimation. These bits of knowledge you present us with are very nutritious to the brain.

  26. Very interesting video. However, I would have found it interesting to hear why the Bragg effect happens, in qualitative terms of course.

  27. There is no doctor more useful than the other. Sure medical doctors increase your health bar, but other doctors increase our intelligence bar.

  28. I am a survivor….gamma saved me. 26yrs now. Proton therapy is promising. Focused gamma camera multiple beam awesome idea. שלום

  29. If I were President – and God knows I would have to be an improvement – Dr. Lincoln would be in my cabinet, maybe Secretary of Explaining Complicated Stuff.

  30. Chemo and worse Rad therapy are both scams, Avoid both like the plague of black death. Ck out Dr Streeter's vids on youtube.
    Take either or both, your life is over.

  31. Dr. Wilson is my hero. He is the BEST kind of doctor. One that knows, loves, and celebrates the secrets of physics and is excited to tell us in layman’s terms all about it. You will know a wise man because he will be the first to admit the limits of his expertise. Unlike crackpots that will give you unlimited “answers” until pseudoscience exhausts them.

  32. The device you show for conventinoal radiation therapy is an accelerator. It accelerates electrons via a linac and either uses them directly with the specific energy achived with an electromagnet filter or it slams them into a gold or tungsten target releasing high energy xrays in the 6 to 20 Mev range. I do not think those are high energy enough to be called gamma.

  33. What happens to the tumours after they are hit by protons? Do they disappear? How long is the therapy? What's the success rate? What are the conditions? Great video and big thanks

  34. It takes under 3 minutes for a tumor to disappear. I recommend you youtube search for Anointing Water videos and try it is another close person develops cancer. Otherwise you might lose him again.

  35. Due to ionized electrons having enough energy to ionize other electrons the dosis maximum with gamma rays actually is not at its maximum at the surface. With rising energy, the dosepeak gets shifted deeper into the tissue (we call that Aufbaueffekt in germany, no idea how it's called in english), one of the reasons why radiotherapists use energies at 6-20MeV.

  36. They used gamma rays back in the days when they used Cobalt sources, but these days conventional radiotherapy are high energetic x rays produced by a linear accelerator

    Also the photons that past through the person have a build up effect so the first 2 centimeters of the surface aren't getting the full dose

  37. Great way to explain proton therapy. I'm currently in treatment using this type of therapy
    You explained this way better than I was told!

  38. My 15 y old son got 5 weeks of treatment and his tumor is GONE. Proton therapy is my new best friend. Much better use of atoms than proton bombs.

  39. Hello. I belive I was expose to radiation at work hospital because when I went to dispose the trash the radiation alarm went crazie loud and I was carrying that bag for almost 8 hours. I have never had suffer from cosntipation in my whole life but now I am. I am wondering if this expose its the cause of it. Can anybody help me please.

  40. Thank you for the video it was a very great simplistic yeah detailed overview. I have been told I need a biopsy of the prostate. So I’ve been looking up information online

  41. Proton therapy sounds great and all – but you have to consider safety as well.

    A proton beam get boosted to a certain energy level. As it passes through the skin, the brag peak is occurs at a certain dept in the patient. If that dept changes or the tissue in that path varies too much – then the brag preak will put its energy down elsewhere. It might miss the target. And thats far worse than spreading out low doses to surrounding tissue.

    A photon beam can also get its energy boosted or lowered to change how fast it loses its energy in tissue, but it will still go all the way through a patient, losing most of its energy. Current techniques allow heavy metal slides in the head of the device to block off parts of the beam and give it really odd shapes. These shapes have been computer calculated, to lay down dose where it should go – and block as much as possible where it should not go. Protons are heavier and require different techniques of shielding and shaping. You could say, current techniques make photons more agile, and treatment options more varied.

    Additionally, not all treatments are the same. Take a child with a tumor in the spinal canal. You would say, lets hit that tumor with protons and spare the rest of the healthy tissue. But this is bad medical advice (I am a radiotherapy technologist – people think we are the nurse – but i make these treatment plans in software for the machines). If you hit part of a vertebra with a dose, then later in life, the child will grow lopsided. And so, you must spread out the dose over the entire vertebra evenly, so the reduced growth is even and the patient ends up only a bit shorter in adult life – rather than tilted to the side.

    These quirks in treatment may mean that the benefit of proton therapy actually works against it, and photon therapy has the benefit still about 50% of the time in most child cases.

  42. This is so misleading, bad, poor science. Please contact me on private and you will get what this video deserves.

  43. Its amazing how light protons cause cancer but light protons can also reduce it.
    Weird polarization going on there.

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