Radiobiology with cyclotron proton beams: A viability study

Cyclotrons capable of accelerating protons up to about 20 MeV have been worldwide installed. Although their purpose is mainly positron emission tomography (PET) radioisotope production, they are equipped with several beam lines suitable for scientific research. Each beam line may typically deliver proton currents up to 150 μA (10¹⁵ particles/s). Radiobiological and radiophysiological studies using of these beam lines may contribute to further improve proton therapy results, namely by giving input to pertinent scientific questions, with some of these questions analyzed here. Once the rationale for radiobiological and radiophysiological studies is substantiated, we investigate the viability of building an experimental setup adjusted to one beam line of a proton cyclotron recently installed at the University of Coimbra (a Cyclone^® 18/9 HC, from IBA - Ion Beam Applications, S.A.). First GEANT4-based Monte-Carlo simulations are compared with well-estabished ion simulation codes. The precision of these results, as well as that of other published experimental data, points to experimental challenges to be addressed in order to thrive towards a high-precision dosimetric setup. Such high-precision is required by law for radioherapeutical applications, which we would like to mimic experimentally so that potential future results have impact on the medical physics community. We finally show a setup scheme, adjustable to one beamline of the cyclotron, capable of equally providing very low (1 cGy) and high dosage (100 Gy).