Tumor irradiation in mice with a laser-accelerated proton beam

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. Sources capable of providing these ultra-high dose rates are under investigation.

Current developments at the high-power laser source Draco operated at Helmholtz-Zentrum Dresden-Rossendorf enabled the production of polychromatic proton beams with energies greater than 60 MeV 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. This 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 results demonstrate a complete laser-driven proton research platform for diverse user-specific small animal models, able to deliver tunable single-shot doses up to around 20 Gy to millimeter-scale volumes on nanosecond time scales, equivalent to around 10⁹ Gy/s, spatially homogenized and tailored to the sample. The platform provides a unique infrastructure for translational research with protons at ultra-high dose rate.