Tumor irradiation in mice with a laser-accelerated proton beam

Abstract

Recent oncological studies identified beneficial properties of radiation applied at ultra-high dose rates several orders of magnitude higher than the clinical standard of ~1 Gy/min. At the high-power laser source Draco, operated at Helmholtz-Zentrum Dresden-Rossendorf, a complete laser-driven proton research platform for diverse user-specific small animal models was demonstrated. Tunable single-shot doses up to around 20 Gy to millimeter-scale volumes on nanosecond time scales, equivalent to instantaneous dose rates of around 10^9 Gy/s. Spatially homogenized dose distributions tailored to the sample can be delivered with polychromatic proton beams of energies greater than 60 MeV, which have been provided with unprecedented stability and long-term reliability. These achievements allowed to successfully conduct the first radiobiological in vivo study using a laser-driven proton source. The pilot irradiation study was performed on human tumors in a mouse model, showing the concerted preparation of mice and laser accelerator, the dose-controlled, tumor-conform irradiation using a laser-driven as well as a clinical reference proton source, and the radiobiological evaluation of irradiated and unirradiated mice for radiation-induced tumor growth delay. The prescribed homogeneous dose of 4 Gy was precisely delivered at the laser-driven source. The laser-based proton irradiation platform at the Draco PW facility enables systematic radiobiological studies within an unprecedented range of beam parameters and demonstrate a solution for minimally invasive volumetric dosimetry at ultra-high dose rates.