Beams of hadrons, such as protons and carbon ions, offer some important advantages over X-ray radiotherapy, not least the minimal damage they do to healthy tissue around a tumour. Clinical deployment of such treatment is still in its infancy, however, with most hadron-therapy facilities currently in operation at large particle-physics laboratories rather than hospitals.

The Italian-Belgian joint venture aims to change all that. Up to now, the only instruments able to produce both protons and carbon ions for hadron therapy were synchrotron particle accelerators. A synchrotron is a complex, sprawling machine consisting of a particle ring with a diameter of at least 25 m. A cyclotron, on the other hand, is a compact and much cheaper instrument with a diameter of around 5 m.

INFN's breakthrough is the realization of a multiparticle cyclotron that can generate both protons and carbon ions with the energy needed for hadron-therapy treatment. "The new cyclotron offers a great technological advantage," claimed Giacomo Cuttone, head of the proton therapy project at INFN Southern National Laboratories.

"For the first time, a doctor will have the opportunity to choose to produce ions or protons, according to the kind of tumour, with a compact, easy-to-manage and decidedly cheaper instrument than is traditionally possible. With the ions produced by this new machine, it will be possible to treat tumours at a maximum depth of 18 cm."

Particle therapy works by damaging the DNA of cancerous cells - mostly by ionization - so that they cannot grow and multiply, while minimizing damage to surrounding healthy tissue. It's the same basic principle as X-ray therapy. Photons, though, lose a significant amount of their energy before they reach the tumour, which can damage healthy cells and cause unpleasant side-effects.

In contrast, when a beam of charged particles enters the body, it deposits most of its energy at a depth that depends precisely on the energy of the particles. This means that tumours can be targeted more accurately, allowing a larger radiation dose to be delivered and speeding up the treatment programme.

Carbon-ion therapy shows great promise in the treatment of deep-seated, radio-resistant tumours in the brain, head and neck region, as well as for lung and pancreas carcinomas. Because of its superior directional precision, proton therapy has been shown to be effective against tumours located near organs at risk - for example, in the treatment of cancer of the retina or tumours sited along the backbone.

• Last month, IBA secured an equipment contract worth around $64 m to kit out a planned proton therapy centre at the Universitätklinikum Essen in North-Rhine Westphalia, Germany. The centre will have four treatment rooms - three gantries (isocentric rotational frames) and one fixed-beam room with two nozzles (of which one will be designed specifically for eye treatments). Construction and set-up of the facility will take around three years, with the first patients slated for treatment in 2009.