Cancer: Radiobiology in mice using a laser-driven proton source

Irradiation of tumours in mice using protons from a stable, compact laser–plasma accelerator, is demonstrated in a pilot study published in Nature Physics. These findings provide evidence for the potential of this technique to be used in future research aimed at improving radiotherapy treatments for cancer.

Radiotherapy using proton beams from conventional accelerators is an established treatment for different forms of cancer. Recent studies suggest that the application of much higher radiation doses rates — by several orders of magnitude compared to current clinical standards — might affect the healthy tissue surrounding the tumour cells less than currently recommended dose rates in what is known as the FLASH effect. Laser–plasma accelerators are a promising source to deliver ultra-high proton dose rates that are believed to trigger this FLASH effect.

Florian Kroll and colleagues establish a research platform suitable for the irradiation of tumours in small animal models using proton beams from a laser–plasma accelerator at ultra-high peak dose rates. The team demonstrate the readiness of the accelerator for use in radiobiological research, including its effectiveness in delaying the growth of human tumours (head and neck squamous cell carcinomas) grown on the ears of mice with a uniform dose. The authors used a sample size of 92 mice.

In an accompanying News & Views, Leonida Gizzi and Maria Grazia Andreassi state that “the intrinsic high dose rate of laser–plasma accelerators makes them potentially valuable for studies of the mechanisms underlying the FLASH effect”. They go on to add that they are an encouraging step towards the further use of protons at ultra-high dose rates in translational research.