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Boron Neutron Capture Therapy (B10->B11)

  1. Oct 20, 2009 #1
    Hi! I hope I've posted this in the right section, but it definitely deals with the nucleus, so here goes.

    I'm doing a presentation on Boron Neutron Capture Therapy, which, if you don't know, puts boron inside tumor cells, shines a neutron beam onto those cells, which causes the boron inside the cells to "fissle" (is this really fission?) into Lithium-7 and an alpha particle. This recoiling atom and alpha particle obliterate the cell, thus killing it.

    So, there seems be a paucity of information on this topic (unlike my last project, fusion, which was made awesome by PF!). I have a few questions that I can't wrap my head around.

    1. Has BNCT actually been done on humans? And how was that even possible if you need a reactor or a particle accelerator for the neutron beam? I've never heard of those in hospitals.

    2. This "neutron beam": I can't seem to find information on this: all I understand is that it is a stream of neutrons and it comes either from a reactor or a particle accelerator. But, you would never find either of these in a hospital! So, how do you get the neutrons and how do you turn them into a so-called beam? I get how the collimator works to focus it, but how does the stream happen? Like, can you get a "bag" of neutrons from a reactor and then transport it over to hospital? Bad analogy, I know. :(

    And then because of collisions, this beam becomes low-energy thermal neutrons which can be better absorbed by boron? But why?

    I'm still researching the shell model of the nucleus (and I thought molecular orbital theory was rough!), but this plays a part in boron's unusually high cross-section, which is the surface area that is exposed. If anyone wants to link me a good site, that'd be great. I have one already,


    But, it'd be safe to say that it's a bit over my head right now. Tell me if this is right:

    Boron's neutron configuration is 1s2, 1p3. And it is just one neutron short of filling the 1p(3/2) subshell. The same goes for it's proton configuration. Or do they go together and it actually has a nucleon configuration 1s2, 1p4, 1d2? Because it's just ONE neutron short, it really wants to fill another neutron? So it's like the halogens, but with neutrons?

    3. The main reaction when B10 gets hit by a neutron. It jumps to become B11 for like a femtosecond (I read it somewhere, but I don't remember the number). Why is this B11 unstable? It now is exactly the same as a B11 atom, which is stable (and accounts for 80% of all boron!). Why does this "decay" into lithium and an alpha particle?

    Whew....thanks a ton already. :) If someone knows anything (like ANYTHING) that could help, that would awesome.


  2. jcsd
  3. Oct 20, 2009 #2

    Vanadium 50

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    If you google "neutron therapy", there are 177,000 hits. Note that this isn't specifically boron targeted.
  4. Oct 20, 2009 #3

    Huh, well, that helps! :) Thanks,

  5. Oct 20, 2009 #4
    All right, I think neutron therapy is different from neutron capture therapy.

    Neutron therapy seems to be like "regular" therapy where the radiation attacks the cell's DNA. Neutron capture is something "picking up" a neutron and then kind of blowing up inside the cell: no DNA needed.

    But, it does answer the question of the beams: yeah, they just have particle accelerators, lol!

    I guess that only leaves one question: why B11 decay if it is a stable isotope? Is it the energy of the neutron beam? But, due to the collisions, the neutron only has .0025eV when it reaches the boron atoms? Is that enough to cause a decay?

    Thanks, Vanadium; I think you helped me on my fusion project, too!

  6. Oct 21, 2009 #5


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    The reaction is NOT B10 + n -> B11 -> He-4 + Li-7

    It is DIRECTLY B10 + n -> He-4 + Li-7

    There is no ground-state B11 intermediate step.

    This is like fission in U-235: if you irradiate U-235 with neutrons, there are two possible reactions:

    capture: U-235 + n --> U-236 + gamma

    and fission:

    U-235 + n --> 2 fission products and some neutrons

    They are totally different channels.
  7. Oct 21, 2009 #6
    Thank you for the reply, :)

    What is this site talking about then?


    I mean, the image says that you get B11 for about ~10^-12 seconds...I just don't understand what makes that "B*11" different from a "B11" atom. Like why doesn't boron accept the neutron and then just stay that way? Is it "excited" because of the energy of the neutron? Say we had like a cold neutron with a lower energy: would that make B10 into a stable B11, i.e. no decomposition?

    All right, so it's not "fission", just neutron capture. Thanks a ton; will avoid that word in the presentation.

    Sorry: I feel like this is a key part to why this reaction happens and I'm a little afraid my teacher might not like it if I don't have an answer.

    Thanks again,

    Last edited by a moderator: Apr 24, 2017
  8. Oct 21, 2009 #7
    I hate to bump this thread, but if anyone knows the answer to this last question, that would be splendid as the presentation is tomorrow at 12:40PM.

    But, nonetheless: thanks a ton, guys. I really appreciate the help, yet again. You help poor ignorant people like me, and truth be told, I'm considering a physics major because I've learned so much here and it's just so interesting! :D

  9. Oct 22, 2009 #8


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    Yes, it is an excited state. It is not excited because of the KINETIC energy of the neutron, but rather because the B-11 system has another level scheme than the B-10 system, so if you ADD a neutron to a B-10 system, you are high-up in the B-11 system as compared to the ground state of the B-11 system (about 2.7 MeV higher actually).

    The ground state of B-11 is lower than the ground state of B-10 + ground state (hey! what else) of a free neutron.

    A similar thing happens in chemistry with dissociation reactions. Note that there doesn't always need to exist a bound intermediate state.
    Last edited by a moderator: Apr 24, 2017
  10. Oct 22, 2009 #9
    Beautiful! :D : D :D Thank you for this bit so much, I barely fit it in, but it's all good!

    I think my teacher really liked it! He was pretty impressed, too, which is a good thing in itself.

    2.7MeV sounds just about right. :) Thanks again for all the help, guys: absolutely amazing!


    And, if you guys want, here is a link to the Powerpoint! There are some slides with no words which might make things kind of confusing...like the spallation image is actually where I (tried to) explain how particle accelerators work.

    MD5: F27C1B46889C088EA5CBC86F0BC108D6
    Last edited by a moderator: Apr 24, 2017
  11. Mar 31, 2010 #10
    hi! i search for boron neutron capture teraphy...are you have got any information this subject?please ı need help..
  12. Mar 31, 2010 #11
    Do you have any specific questions? Have you looked at the Wikipedia page for it? MIT has an oldish page on it, too.

  13. Mar 31, 2010 #12
    ya ibrahim ben şimdi derdimi burda ingilizce anlatamıcam açıkçası bu benim tez konum ve çok kapsamlı bişey bulamadım sende bnct(boron neutron capture teraphy)ile ilgili bilgi varsa bana gönderirmisin acaba şimdiden teşekkr ederimm
  14. Mar 31, 2010 #13
    Hmm...well, I actually don't speak Turkish. :(

    From what Google Translate tells me, yeah, you're right. There aren't too many resources online which is the reason why I created this thread.

    I would try looking through this thread. Is this for a homework assignment? What information do you need that you're lacking?
  15. Mar 31, 2010 #14
    ibrahim inşallah cevap atarsın lütfen çok acil lazım bana
  16. Mar 31, 2010 #15
    Now I worry about my English here, or Ibrahim anlatamıcam position, and frankly this is my thesis in you can not find anything too comprehensive bnct (boron neutron capture teraphy) gönderirmisin me wonder if there is information already ederimm Special thanks

    Daha iyi bir çeviri ile katkıda bulunun
  17. Mar 31, 2010 #16
    how can find information about bnct? my thesis subject is bnct? i find in internet but not enough....actually my translate is bad so i didnt do anything yet
  18. Mar 31, 2010 #17
    have you got any article about it?or internet address...
  19. Mar 31, 2010 #18
    i find general meaning about bnct but i needed comprehensive information..i hope i tell you my problem
  20. Mar 31, 2010 #19
    This article discusses BNCT treatment of patients in the Brookhaven Medical Research Reactor at Brookhaven National Laboratory:


    They have a special room for neutron irradiation, including BNCT, of patients.

    Bob S

    [added] 54 patients were given BNCT treatment. The average post-BNCT-treatment survival time was about 22 months.
    Last edited: Mar 31, 2010
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