Proton minibeam radiation therapy (pMBRT) is a novel therapeutic strategy that has proven to significantly increase dose tolerances and sparing of normal tissue, while achieving tumor control equivalent to or better than conventional radiotherapy in high-grade gliomas in small animals. pMBRT uses submillimetric proton beams, about an order of magnitude smaller than the beams used in clinical practice. The current implementation of pMBRT with mechanical collimators, although valid, has shown its limits: rigidity, reduction in efficiency and production of additional secondary neutrons.
One potential solution, explored by the new SIRIC team New approaches in Radiotherapy headed by Yolanda Prezado UMR3347 / U1021 is the generation of proton minibeams by magnetic focusing. With that aim they have designed a new optimized nozzle which could be integrated at existing clinical centers. This design uses conventional beamline elements and has a moderate focal length of approximately 1 m and a shortened air gap of 10 to 30 cm. This new nozzle is capable of providing beam sizes between 0.66 and 1.67 mm FWHM at clinically relevant energies.
It can therefore be considered appropriate for pMBRT, leading to an optimal implementation of pMBRT. It could allow a more effective and flexible treatment, accessible to 3D intensity modulated treatments. This is a major development in the project that approaches pMBRT a step closer to patients’ treatments. A patent has been filed.