Anti-Matter's Potential in Treating Cancer

eldavojohn writes "The BBC is taking a look at how atomic physicists are developing cancer treatments. A step past radiotherapy, the CERN institute is publishing interesting results: 'Cancer cells were successfully targeted with anti-matter subatomic particles, causing intense biological damage leading to cell death.' The press release from last year is finally sparking interest in the medical community."

Re:brilliant

[zebadee]

Thats kind of the purpose of the article, if you read it. They compare using charged particle beams to traditional radiotherapy treatment and comment that using particle beams allows the raditation to be better focused on the tumour (in this case a spinal tumour), leading to less death of surrounding tissue.

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Re:Okay n00b question

[radtea]

Antimatter is... just as it sounds. The opposite of matter.

"Matter" in ordinary parlance has various important properties: solidity, resistance to motion (otherwise known as mass) and so on.

Anti-matter has every single one of these properties, so it is not particularly helpful to say it is "the opposite of matter" because it is not.

Anti-matter is simply matter that consists of anti-particles, as correctly indicated by the article you link. Anti-particles are just like ordinary particles except that they have the opposite charge, parity or magnetic moment (in the case of neutrons). This minor change results in a fairly large cross-section for mutual annihilation when an anti-particle scatters off of its corresponding particle.

Re:Okay n00b question

[Planesdragon]

Wrong.

No, that's what he said.

Your failure to grasp his words does not invalidate them, it merely illuminates your own poor understanding of the topic.

Let's put it another way: if there was an anti-sun with an anti-solar system, exactly like Earth but with every particle the inverse of our Earth, they would be exactly the same. (Even when they eventually met and obliterated each other -- matter blows up antimatter just as well as antimatter blows up matter.)

Re:Ah yes..

[speleo]

Because setting off miniature broad-spectrum emp blasts inside your body it a GOOD thing.

It is. Already being done: Positron emission tomography [wikipedia.org].

Re:taking people for a ride

[thrawn_aj]

the research is completely bogus..... antimatter is a very unstable substance that cannot survive in our universe, because it combines with matter and both annihilate each other... for example an electron and a positron on combining mutually annihilate & produce photons.... In this regard anti matter can kill normal cells too with equal efficacy. Since there is no selectivity in this, it is as good or bad as radio therapy.. another thing, antimatter can be produced thru nuclear reactions only...so you can worry about things like nuclear laws, terrorists etc.

The blanket statements I have read so far are contrary to the facts. Surely you folks have heard of PET scans (http://en.wikipedia.org/wiki/PET_scan [wikipedia.org]), a quite ordinary procedure these days? Well, PET stands for positron emission tomography, a really cool mapping technique which is based on low doses of a radioisotope that's chemically incorporated into a sugar being injected into the body. Based on the sugar properties (these can presumably be tailored to the purpose at hand), it then concentrates in areas of interest (there's your selectivity :P). The neat thing is how the annihilation takes place. When a positron gets near an electron, they don't actually get destroyed right away. For one thing, it's highly improbable that the expectation values of their momenta are precisely directed toward each other.

What we get then is actually a great example of an "exotic atom" - the two mirror particles form an unstable "atom" called positronium which is extremely short-lived and which decays into two photons going at 180 degrees to each other. This is important because that is the only way you can detect such an annihilation taking place. At any rate, my point is that this is hardly a "high-energy" application as so many science hacks have sneeringly pointed out here so far. Radiology is an established field of medicine and one reason it is so is because radioisotopes can be made so damn selective (tracers anyone? :P).

Re:25 Billion per gram = 25 bucks per nanogram

[ceoyoyo]

In PET you don't inject positrons. It's positron EMISSION tomography. You inject a substance that, when it decays, emits positrons, then they quickly run into an electron and annihilate, producing two gamma rays, which you detect.

These story is about using anti-protons (very different than positrons) and they're using a beam (well, more than one beam for an actual treatment) of reasonably slow ones. As stated in the article, there are really only a couple of places in the world that can produce such a beam and the equipment to do it is very large.

In contrast, for PET you just need a cyclotron (costs a few million) to make the radio pharmaceuticals for you. My hospital is installing one. But they're not going to be making anti-proton beams any time soon.

why it makes sense

[bcrowell]

First off, heavy ion beams make sense as a way of treating cancer. The reason is that when a heavy ion passes through matter, it decelerates along a straight-line path, and deposits a very large percentage of its energy near the very end of its path. If you compare with x-rays as a radiation treatment, x-rays deposit energy in an exponential-decay pattern, so if you're treating a brain tumor with a pencil beam of x-rays, the tissue that gets hit with the most radiation is the skin, followed by the skull, followed by the good parts of the brain, followed by the tumor. Now in reality you don't use a pencil beam, you use a focused beam, so it's not quite that bad, but focusing also works with heavy ion beams (I believe you actually rotate the patient, not the beam). So with heavy ion beams, you get energy concentrated near the tumor for two different reasons: (a) focusing, and (b) the pattern of energy loss, which is peaked at the end of the trajectory.

OK, now about antimatter. An amazing number of posters apparently (a) haven't read the article, (b) haven't understood the article, or (c) don't know enough physics to make heads or tails of any of this.

1. Antimatter is the same as matter except that it has the opposite charge.
2. No, you don't have to handle samples of it. They make antiprotons in a particle accelerator, and in the experiment, they delivered it to a sample of hamster cells suspended in gelatin. You'd just put the patient in the beam of the accelerator. This has already been done with beams of protons on real patients. There's absolutely no difference, in principle, between delivering a beam of protons to the tumor and delivering a beam of antiprotons.
3. Yes, antimatter is the most expensive stuff ever made. No, that isn't particularly relevant, because you're not feeding it to the patient in gram quantities.
4. At present, there is no dedicated medical facility where patients could get exposed to a beam of antiprotons, and there may never be. What you'd have to do, for the foreseeable future, is bring your patient to a particle acclerator, get him some beam time, and place him on the receiving end of the beam. Although beam time is incredibly expensive, it's not necessarily true that you'd have to pay for 1 hour of beam time in order to give the patient 1 hour of treatment. There may be times when the accelerator is being tested, and the beam would otherwise just be wasted. There may be times when someone is doing an experiment with 1 femtoamp of antiprotons, but they can spare 0.01 femtoamps of their beam to be diverted to the patient. Or there may be times when it's just not possible to book 100% of the available beam time for physics experiments (e.g., something goes wrong with an experiment, and they can't use the rest of their beamtime).
5. The reason a beam of antiprotons is four times more effective than a beam of protons is that after the antiproton delivers a bunch of energy through electrical interactions with electrons, it then annihilates itself with one of the protons in a nucleus in the tumor. This is such an energetic process that I imagine every single proton and neutron in that nucleus goes zipping off separately, with energies in the MeV range. These neutrons and protons then deposit their energy in the tumor as well.

Re:brilliant

[imsabbel]

gamma knife= bad at best, horrible in practice. There IS NO SAFE LEVEL FOR IONIZING RADIATION. Splitting it in 8 beams only increases the amount of affected tissue. The only reason its in use is that its marginally better than dying.

Bragg-peak of decellerating particles== huge dosage in a very tiny volume, relatively little interaction of the particles during the inition part of ther journey through the body.

And, as i post this right now from beamline 8.0 of the Advanced Light Source in berkeley, i can tell you that biological molecules have nice brought absorption spectra, and while there might by sharp pi-resonances, those are smeared out a lot in liquid solutions (plus, the carbon edge is really crowded, there is no empty space to "design a molecule" to.

Re:Okay n00b question

[flyingfsck]

Get a copy of Prof Hawkins' "A brief History of Time". He explains it all really well and there is only one formula in the book.

Re:Ah yes..

[stam66]

Non-specific refers to the fact that to get to cancer cells (assuming you can localise them) you have to get through normal tissue, often a lot of it.

If it were simply a matter of "aim a particle beam" while adjusting other properties, it would have been done decades ago. Current non-anti-matter-particle beams or EM radiation are more than potent to kill cancer cells. Unfortunately it is equally deadly to normal tissues, which restricts it's current use. Radiotherapy in various forms has been around for ages and is effective, but is limited because of it's non-specificity.

How then is "anti-matter" any better? and to my knowledge, PET is a diagnostic test, not a therapeutic intervention (yes, i AM a doctor).

Re:brilliant

[hondo77]

gamma knife= bad at best, horrible in practice. There IS NO SAFE LEVEL FOR IONIZING RADIATION. Splitting it in 8 beams only increases the amount of affected tissue. The only reason its in use is that its marginally better than dying.

As someone whose wife went under the gamma knife, I have to tell you that you are full of shit...at best. She went under in the morning to zap a brain tumor and I took her home that afternoon (or was it the next morning?--I forget which). The tumor was completely destroyed and she suffered no ill-effects whatsoever. Major brain surgery, one day in the hospital, no cutting, no side-effects. Yeah, that was pretty horrible.