Background and Aims

Laser-driven ion acceleration is attracting significant interest in the radiobiological community, as it allows to deliver dose in ultrashort bursts with high dose rates (10⁹-10¹⁰ Gy/s), opening up for investigation novel regimes of radiobiology. These studies require the implementation of bespoke and innovative arrangements for beam delivery and dosimetry.

Methods

The PW VULCAN and GEMINI laser systems at the Rutherford Appleton laboratory were used to generate, respectively, proton and carbon ion bunches. 35 MeV protons and 10 MeV/u carbon ions were magnetically selected and used to irradiate 2D and 3D biological samples, in single exposures. The 2D-samples were plated on a dish and placed inside a vertical holder while 3D models (Glioblastoma neurospheres) were immersed in cell culture medium and placed at the bottom of a thin-walled 3 mm diameter polypropylene tube. Dosimetry was performed on every shot by employing previously calibrated, unlaminated EBT3-Radio-Chromic Film (RCF) for carbon ion dosimetry, while standard EBT3-RCF was used for the proton measurements.

Results

Doses in the 1-5 Gy range with 10% dose variation over 3x3 mm² surface, were delivered to the cells and measured. The proton depth-dose profile along the 3 mm thick tube was evaluated with an EBT3-RCF stack phantom, showing a 5% dose uniformity along the whole tube thickness.

Conclusions

The irradiation and dosimetry approach enabled controlled irradiation of 2D and 3D samples, with a shot-to-shot precise dose determination.

Acknowledgements

This project 18HLT04 UHDpulse has received funding from the EMPIR programme co-financed by the Participating States and from the European Union’s Horizon 2020 programme.