Author Of 2 Presentations
DOSIMETRY AND BEAM DELIVERY ARRANGEMENTS FOR SINGLE-SHOT, ULTRA-HIGH DOSE-RATE RADIOBIOLOGY EXPERIMENTS EMPLOYING LASER-ACCELERATED IONS
Abstract
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.
FIRST RADIOBIOLOGICAL EVIDENCE OF LASER-DRIVEN CARBON ION EFFECTIVENESS AT ULTRA-HIGH DOSE RATE
Abstract
Background and Aims
The normal tissue sparing effects of FLASH radiotherapy have revived interest in ultra-short pulse, ultra-high dose rate (UHDR) radiobiology, with several recent FLASH and UHDR pre-clinical studies using low-LET radiation. High power lasers enable the delivery of Gy level carbon dose at dose rates > 109 Gy/sec, opening up to investigation the still unknown radiobiology of UHDR, high-LET radiation
Methods
At the Gemini Laser of the Central Laser Facility, Rutherford Appleton Laboratory, Glioblastoma stem like cells (GSCs) were exposed to 1 Gy of 10 MeV/n carbon ions in single pulses of ~ 400-picosecond duration, at a dose rate of 2.5 x109 Gy/sec. Carbon ions were accelerated by focussing 45 fs, 6 J laser pulses onto 10-25 nm thick carbon foils at intensity ~ 6 1020 W/cm2. We used the 53BP1 foci assay to study carbon ions induced DNA damage and compared the results with 225kVp X-rays induced DSB damage in the GSCs.
Results
Laser-driven carbon ions induced complex DNA DSB damage, as seen through persistent 53BP1 foci (11.3 ± 0.5 foci per cell) at 24 hrs, compared to X-rays where the foci levels reduced to near the background levels. The relative foci induction values of laser-driven carbon ions normalized to X-rays was found to be 5.75 ± 0.51
Conclusions
Overall, this is the first study to report the radiobiological effectiveness of laser-accelerated carbon ions, demonstrating a method to accelerate and deliver high LET carbon ions in radioresistant GBM stem cell models in single ultrashort single sub-nanosecond pulses.