A wedge-shaped device could make the particle accelerators used for proton therapies in medicine an even more effective tool for treating cancer.
Beams of protons can be used to kill tumour cells. In traditional radiation therapy, radiation moves through the body before and after hitting the tumour, but protons tend to stop after reaching it. This means that fewer parts of the body are exposed to the treatment, which reduces side effects.
However, the process of producing the right protons is long and costly. at the Paul Scherrer Institute in Switzerland and his colleagues set out to address this by improving how the proton beams are controlled.
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Proton beams typically come out of particle accelerators called cyclotrons, but the particles have to be carefully calibrated to be used for cancer treatment. Researchers conventionally use a 鈥渄egrader鈥� that lowers the protons鈥� energies, then directs them through a set of slits that only let protons with the right amount of energy pass through.
But this procedure is so wasteful that only about 0.1 per cent of protons from the cyclotron end up being used while the rest are lost, says Maradia. His team worked out that replacing the slits with a plastic, wedge-shaped device could significantly improve this rate.
The key property of the wedge is that rather than screening out protons, it adjusts them instead, reducing the protons鈥� speed as they move through the wedge. The researchers installed the wedge into a proton therapy setup that is normally used to treat different forms of eye cancer and found that the number of protons successfully transmitted doubled.
Further calculations showed that if a proton therapy facility was built to contain the wedge to begin with, this improvement could be as high as 100-fold, says Maradia.
at the Mayo Clinic in Minnesota says that proton therapy is particularly well suited for tumours that are close to sensitive organs, or for use in children. Increasing the dose of protons would also make it more effective at treating some tumours that are resistant to conventional radiation therapy, she says.
Adjusting the energy of the protons while losing fewer of them could also make it easier and cheaper to build new proton therapy facilities because they would require less shielding, which currently serves to block all stray or lost particles, says at the Louisiana State University.
Nature Physics
