Research News
The ion rays required for tumour therapy are produced not by a particle accelerator but by a compact laser: The 150 terawatt Ti:sapphire laser DRACO. Photo: Helmholtz Centre Dresden-Rossendorf
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With Ion Beams from Laser Light Against Cancer Cells
The ion beam therapy against cancer, which was originally developed at the GSI Helmholtz Centre for Heavy Ion Research, is one of the surprising applications of particle physics. But to produce the ion beam, one usually requires a circular accelerator with a diameter of approximately 20 to 30 metres and a weight of several hundred tonnes. The scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) are working on this problem:
"Such large, expensive facilities cannot be afforded on a large-scale. Therefore, one has to find other methods to produce these ions", says Prof. Dr Roland Sauerbrey, Scientific Director of the HZDR. "We investigate how to accelerate such protons or carbon ions by way of laser beams from high-power lasers. We want to optimise this new method so that it can be used also for medical purposes. To arrive at a prototype, we reckon with a development time of approximately eight years as of now." The method is clear, though. A facility which could fit into a normal sized room is to shoot particles with ultrashort light impulses out of a razor-thin material foil. This procedure already is being tested with the high-power lasers of the HZDR. In doing so, amounts of energy are reached that surpass the energy produced on earth by ten to a hundred times in the time light requires to pass through a human hair. "The laser beam here is focused to a diameter of a few micrometres and hits a thin metal foil with a "pressure" of several billion bar. The electrons are thereby accelerated forwards and pull ions from out of the metal foil in their wake", Sauerbrey explains the principle. The technical and mechanical solutions which are being developed at the Helmholtz-Zentrum Dresden-Rossendorf are for some part unique. This includes novel imaging processes to localise and render visible cancer tumours. In these activities, the HZDR experts work closely together with the University Hospital Dresden, the Technical University Dresden and the German Cancer Research Centre in Heidelberg in order to push forward development: For instance, the ion beams for cancer therapy currently are controlled by static magnetic fields, but the Dresden scientists can also imagine using pulsed magnetic fields for this purpose. "Here in Rossendorf, we create the strongest pulsed magnetic fields in Europe and have great expertise in this field. This knowledge will help us in developing beam guidance systems for ion beams for cancer therapy", says Sauerbrey.
