Slashdot Mirror
Treating Cancer with Beams of Anti-Matter
Zeinfeld writes "According to this Economist article scientists at CERN are using beams of antimatter to destroy cancer cells. The basic idea is that you make some anti-protons, whizz them round in a accelerator to get them moving at a decent rate then fire them at living tissue. They burrow down to the desired depth, find a friendly proton and do a spot of mutual anihilation, releasing sufficient energy in the process to kill a cell or two. The trick is that matter/anti-matter anihilation is a bit like nuclear fission, it does not work if the particles are moving too fast. The anti-proton has to be moving slowly enough to get pulled into the orbit of some atomic nucleus and actually collide. This allows the treatment to be fine tuned so it only affects the tissues at a very specific depth - unlike traditional therapies which zap everything in the line of fire."
This is what they told me when I was only visiting CERN last May. I'd imagine that the information could have been aquired on the cern website for a long time before that.
Many hospitals already have particle accelerators in them. It's just a matter of scaling them up...
For dolts (like me) who had no clue what antimatter really is, I found this article over at Scientific American that gives a good overview and explains what exactly (and why) antimatter is. It's readable, too, to a non-physics geek.
--trb
Even regular X-Ray therapy those pesky alpha particles receive quite a spin, so they go straight to the set depth and then disperse, thus forming a focal point, without destroying any tissue in-between.
What?!? This sentence makes no sense.
X-rays and alpha particles are two different things. Alpha particles are high energy helium nuclei emitted by the decay of large atomic nuclei (Uranium, plutonium...). X-rays are high energy light. I doubt alpha paticles are useful for treating cancer as they do not penetrate skin.
Are you referring to radiation treatments where they rotate the radation source around the person , with the axis of rotation being the targeted tumor. In this case you can deliver a much higher dose of radiation to the targeted region while minimizing the radiation dose to any individual intervening region of healthy tissue.
Ever heard of a Bragg Peak?
Ever heard of multi-beam treatment?
Sheesh!
Actually, if you read the article instead of the Slashdot synopsis. The point of using anti-protons is that you get the same effect as Bragg Peak (didn't know the name until you mentioned it thanks!) with regular protons. In addition, shortly after dumping most of the ionization energy into the tumor tissue, the anti-proton meets a proton causing more damage at the targeted location. I think the idea is that even while proton treatments can be well targeted they still deliver radiation doses to intervening tissue, by using anti protons you can deliver more radiation for the same dose to intervening tissue.
Fermilab has had a neutron beam therapy very similar to the CERN anti-proton therapy since 1976. Neutrons are radioactive by themselves with a half life of about 14 minutes. Once deposited in some tissue they will either decay or combine with an atom to form a radioactive isotope (which then decays).
There are other unique radio therapies including Brachytherapy (place radioactive isotopes in the tumor) and Radioimmunotherapy (attach a radioactive isotope to a nonoclonal antibody). The latter sounds very neat and targeted. But none address the fundamental problem -- why do cells turn cancerous.
-- Bob
1^2=1; (-1)^2=1; 1^2=(-1)^2; 1=-1; 1=0.
You don't have any idea what your talking about, do you?
X-Ray therapy would involve gamma particles (aka photons) not alpha particles. Alpha particles are ionized helium.
As for the whole, spin thing, you must be smoking crack.
What is sometimes done, is stereotactic radiotherapy. Multiple beams of gamma rays are aimed so that they all cross at a single point. Each beam by itself won't cause much damage, but at the point where they cross, the combined dose is enought to kill the tumor. You can also do this by spining a weak beam for an extended period of time. Maybe that is what you meant?
The Economics of Website Security
Focusing I am 100% sure of. And the fact that x-ray is also depth-contrallable treatment I am even surer (if there is such a thing).
Yes, but it's not depth-controllable in the sense you're thinking of. They maximize the damage to the region of interest, but the surrounding regions do get irradiated, just to a lesser extent. The degree to which they're irradiated depends on either the number of beams (in a multi-beam apparatus) or the rate of rotation (in a rotating apparatus).
The problem is that if you want to increase the dosage to a certain area, you need to increase the rate of rotation or the number of beams to keep the same low level of damage to the surrounding area.
With this method, you can arbitrarily increase the dosage (beam luminosity) without increasing the damage to the surrounding area significantly, with no change in the apparatus. (This is a 'probably': if the depth dependence is exponential, and the luminosity dependence is linear, then doubling the intensity doubles the dosage everywhere. However, depending on what the critical distance is, if it's really short, then it doesn't really matter how much you increase the luminosity, because all of the rest of the body is "far" from the 'impact point', and is way, way down on the exponential decay anyway).
By way of explaination, PET (positron emission tomography) scanners require particle accelerators in order to produce on-demand isotopes with very short half-lifes. Thus, any hospital with a PET scanner already has a particle accelerator.
Be careful in just taking what a hospital technician might tell you. Most of the med techs I've known or met were pretty good but some have just mind-boggling levels of ignorance. I was in for a barium contrast CT this spring and the tech told me that the barium solution would feel hot when injected theough the IV. He then went on to tell me that this was because of 'friction between the Barium and the inside of my blood vessels'.
It took all my will power to not kick him.
Anyway, you can't really focus X-rays in a normal setting, the mirrors involved for X-ray manipulation are very expensive. Rather what happens is that a single straight beam is sent theough the tumor at different angles. Think of several flashlight beams crossing at the same point. Where the beams cross, it's much brighter. This lets you get the correct amount of X-rays to the tumor and minimize the amount in the surrounding tissue.
Also, re the previous post - X-rays are from X-ray energy photons, not gamma energy photons. It's a bit nit-picky but there is a huge energy difference between X-rays and gamma rays.
Charged particles are another ballgame altogether. I'm told (remember, IANAP) that the rate of energy loss of a charged particle in dense matter is strongly speed-dependent and it goes up as the speed goes down (see other posters re: Bragg peaks). This allows a beam of charged particles to be calibrated for depth, because it will run into a "sand trap" as it loses energy going through tissue and deposit most of its energy close to the end. I've heard of pions (pi mesons) being used for radiation treatment for just this reason.
Antiprotons would be another quantum leap (pun intentional) in effectiveness. The energy the antiproton spends busting molecular bonds and making free radicals on its way in is only the beginning. When an antiproton hits a nucleus, it annihilates a proton and forms three pions (pi+, pi-, and pi0). The pi0 is its own antiparticle and decays into two gamma rays which probably don't do much, but the pi+ and pi- are also heavy charged particles. If they aren't moving very fast they would deposit most of their kinetic energy within a very short distance of the site of annihilation, busting up more molecules and making more free radicals. Then they decay to muons (which are pretty hard to stop and probably wouldn't do much from then on). On top of this, any nucleus heavier than hydrogen is going to be transmuted by the loss of the proton, changing its chemistry if not shattering the molecule it's in from the momentum change. That makes antiprotons a triple-threat.
Free radicals do things like chewing up proteins and slicing DNA strands. Enough of this and even a cancer cell can't function, and it dies.
Time is Nature's way of keeping everything from happening at once... the bitch.
Biologists have a pretty good understanding of how cells turn cancerous, but that doesn't result in clear and obvious treatments.
Biologists have a good idea of what causes cancer in general, but not necessarily for a given individual. There are many causes to cancer - carcinogens, genetic predisposition, etc. - and often several of these factors will combine before someone gets cancer.
In fact, the body has the ability to kill cancer cells if it recognizes that there is a problem and if the cancer hasn't become too large or encapsulated. All those crude methods help shift the balance back in the body's favor.
Usually, the cell isn't actually cancerous at this point. Rather, it has some damaged DNA (or other problem) that is potentially hazardous. So, instead of taking the chance, the body gets rid of the cell. Often, once a cell actually becomes cancerous and is growing out of control, it's too late for the body to do anything.