Conformal radiation therapy with hadron beams and the programs of the TERA Foundation

Proposed fifty years ago, tumor therapy with charged hadron beams has been under rapid development since 1993-94. Indeed hadrontherapy was born in 1938, when neutron beams have been used in cancer therapy, but it has become an accepted therapeutical modality only in the last five years. Fast neutrons are still in use, even if their limitations are now apparent. Charged hadron beams are more favorable, since the largest specific energy deposition occurs at the end of their range in matter. The most used hadrons are at present protons and carbon ions. Both allow a dose deposition which conforms to the tumor target. Radiobiology experiments and the results of the first clinical trials indicate that carbon ions have, on top of this macroscopic property, a different way of interacting with cells at the microscopic level. There are thus solid hopes to use carbon beams of about 4500 MeV to control tumors which are radioresistant both to X-rays and protons. After discussing these macroscopic and microscopic properties of hadrontherapy, the twelve dedicated hadrontherapy centres, which will be treating patients from 2001-2002, are shortly described. Five of them are in the USA and seven in Japan, while no hospital based centre for deep protontherapy is fully financed in Europe. The second part of this review is devoted to the Italian hadrontherapy programme, based on the development of the network RITA, the construction in Rome by the "Istituto Superiore di Sanità" of a novel proton accelerator based on a 3 GHz linac, the design of a linac to boost the energy of protons extracted from a 50-70 MeV cyclotron and the construction in Mirasole, near Milano, of a center for protons and ions known as "CNAO". This center will have a synchrotron, which is under design at CERN in the framework of a collaboration of TERA with AUSTRON and GSI which is called PIMMS (Proton Ion Medical Machine Study) and is headed by Dr. Phyl Bryant.