Description
Laser-based sources of ionizing radiation have been gaining attention for research in radiobiology due to their very high instantaneous dose rates. Studies with cell cultures require stable operation of the radiation source, high flux, and means of dose control. Recently, a first set of related experiments has been accomplished at the two high-power laser facilities in Spain and improvements for future campaigns are under study.
A dedicated X-ray source has been developed at the Laser Laboratory for Acceleration and Applications (L2A2, Santiago de Compostela). It produces bremsstrahlung (< 100 keV) generated by a pulsed laser (1 mJ/35 fs) which is focalized on a rotating copper plate in air at 1 kHz shot rate. 36 samples of a human lung adenocarcinoma cell line (A549) have been irradiated at a mean dose rate of 100 mGy/s. An ionization chamber has been implemented as a real-time dose monitor.
At the VEGA-3 laser of CLPU (1 PW, 27 J at 1 Hz maximum pulse rate), a TNSA proton source developed by IGFAE has been combined with a magnetic energy selector from i3M to obtain a quasi-monoenergetic, 5 MeV particle beam. In a pilot experiment, 27 cell samples have been exposed to several tens of accumulated pulses at a single-shot dose of about 200 mGy.
Our research activities are now centered on increasing the single-shot dose in proton irradiation through optimized TNSA parameters, reduced particle flight paths, and the implementation of beam focussing elements. We plan to exploit the maximum repetition rate of VEGA-2 to multiply the mean dose rate on the cells. In addition, the reproducibility of dose deposition will be improved by a real-time dose monitor.
Grant PID2023-148992OB-C21 funded by MICIU/AEI/10.13039/501100011033 and cofunded by the European Union, ERDF.
