Tumortherapy with ion beams

Beams of heavy-charged particles like protons or carbon ions represent the optimum tool for the treatment of deep-seated inoperable tumors: in contras t to the conventionally used photons the dose increases along with the pene tration depth through the body, culminating in a sharp maximum at the end o f the particle range. In order to achieve a precisely conform irradiation o f the selected target volume, this maximum can be shifted in depth by energ y variation and distributed laterally through magnetic deflection of the pa rticle beam. Because carbon ions have a lateral scattering of only about 1m m at 10cm depth they offer the most conform irradiation. In addition to thi s excellent physical selectivity the biological efficiency concerning cell killing increases towards the end of the carbon ions' range. Therefore, the increase in dose is potentiated by an increase in biological efficiency. F inally, the stopping of the carbon ions can be monitored by tracing a small amount of beta (+) active C-10 and C-11 ions which are produced in nuclear reactions with atoms of the penetrated tissue. This beta (+) distribution can be visualized by applying PET-techniques, thus allowing a good control of the beam distribution. At GSI Darmstadt a heavy-ion therapy unit has bee n designed and constructed in collaboration with the Radiological Clinic an d the DKFZ Heidelberg and the FZR Dresden. The layout of this facility as w ell as the treatment of now more than 30 patients will be reported on. The proposal for the layout of a dedicated medical facility at Heidelberg will be presented (C) 2000 Published by Elsevier Science B.V. All rights reserve d.