Tumour irradiation in mice with a laser-accelerated proton beam

Abstract

Recent oncological studies identified beneficial properties of radiation applied at ultrahigh dose rates, several orders of magnitude higher than the clinical standard of the order of Gy min–1. Sources capable of providing these ultrahigh dose rates are under investigation. Here we show that a stable, compact laser-driven proton source with energies greater than 60 MeV enables radiobiological in vivo studies. We performed a pilot irradiation study on human tumours in a mouse model, showing the concerted preparation of mice and laser accelerator, dose-controlled, tumour-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 tumour 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 millimetre-scale volumes on nanosecond timescales, equivalent to around 109 Gy s–1, spatially homogenized and tailored to the sample. The platform provides a unique infrastructure for translational research with protons at ultrahigh dose rates.

Time-of-Flight spectroscopy for laser-driven proton beam monitoring

“…The predicted depth dose homogeneity features an uncertainty of 5.8 % (2σ), which translates into a maximal dose difference between maximum and minimum depth dose value in the target region of 11.6 % relative to the applied mean dose value in the target region. This value slightly exceeds the desired < 10 % homogeneity uncertainty but pulse accumulation has shown to reduce the depht dose homogeneity uncertainty 31 .…”

“…The 2.2 m long beamline (distance from LPA proton source to irradiation site, Figure 1 a)) is optimized to generate homogeneous mm-to cm-scale volumetric spatial dose distributions at an in-air irradiation site. Hence, ALBUS-2S allows to perform radiobiological studies 31 with small animals and is also readily applicable for e.g., research and development of novel proton LPA detector systems 16 . In this setup the LPA proton source is powered by the Draco PW laser focused onto a ∼ 250 nm thin plastic foil target.…”

“…By adjusting laser pulse energy and hence proton source spectrum, the magnetic field strength of the solenoid and/or the apertures and scatter foils, application-adapted spatial dose distributions with a pulse dose range from ∼ 500 mGy to multi-10 Gy can be generated at the irradiation site. The general performance and capabilities of the ToF BMS will be showcased based on two different operation modes (low dose per pulse (LD)/ high dose per pulse (HD) mode) of the ALBUS-2S beamline, each optimized for specific radiobiological studies 31 . Both settings provide homogeneous dose distributions over a cylindrical volume with diameter of 5 mm and a depth of 4 mm and 3 mm, respectively.…”

Accelerate to the next level

“…Only recently, a proof-of-principle demonstration of free-electron lasing using a laser-plasma accelerator was reported 3 , which paves the way towards their use as light sources. Another example illustrating how laserplasma accelerators pick up the pace towards practical applications is part of this issue: Florian Kroll and colleagues report a step towards the clinical use of laser-plasma accelerators 4 .…”

Krebsforschung mit laserbeschleunigten Protonen

“…Unter der Leitung von Wissenschaftlern des Helmholtz‐Zentrums Dresden‐Rossendorf (HZDR) ist es unserem interdisziplinären Team nun erstmals gelungen, in Tierversuchen Tumoren kontrolliert mit laserbeschleunigten Protonen zu bestrahlen [2]. Bisherige Untersuchungen beschränkten sich auf Zellkulturen [3].…”