Ultra-high dose rate radiobiology and dosimetry at the laser-driven proton accelerator Draco-PW


Ultra-high dose rate radiobiology and dosimetry at the laser-driven proton accelerator Draco-PW

Brack, F.-E.; Reimold, M.; Kroll, F.; Beyreuther, E.; Karsch, L.; Kraft, S.; Leßmann, E.; Pawelke, J.; Schlenvoigt, H.-P.; Schramm, U.; Umlandt, M. E. P.; Ziegler, T.; Zeil, K.; Metzkes-Ng, J.

Background and Aims
Laser-plasma accelerators (LPA) are a viable addition to the ultra-high dose rate accelerator portfolio, as they generate extremely intense proton bunches of several 10 MeV kinetic energy. Efficiently transported and spectrally shaped, a single LPA proton bunch enables homogeneous dose delivery above 20 Gy to mm-scale volumes with a dose rate well above 108 Gy/s. At Draco PW we have recently shown the successful establishment of a proton LPA research platform for small animal studies employing a multi-shot accumulated dose delivery for a mouse model pilot study. [Kroll et al, Nature Physics 2022].
Methods
Reaching the range of FLASH-associated parameters at an LPA proton source requires single-shot irradiation. We performed such irradiations with zebrafish embryos and dosimeters using the pulsed beamline at Draco PW. Since LPA based accelerators are prone to inherent fluctuations of the source, to measure the applied dose, a minimally invasive, online spectral characterization of the delivered proton bunches is necessary. Clinically used ionization chambers saturate under LPA beam conditions. Therefore, we present a scintillator-based time-of-flight (ToF) beam monitoring system for the recording of kinetic energy spectra of single LPA proton bunches. The deduced spectra are used as an input for Monte-Carlo simulations to predict the delivered dose to the irradiated sample.
Results
The ToF ansatz enabled the reconstruction of the kinetic energy spectrum of the transported protons with a relative energy uncertainty down to ca. 11% (2σ). Subsequent Monte-Carlo simulations predict the applied depth dose distribution with an uncertainty of ca. 6% (2σ).
Conclusions
We present a laser-based proton irradiation platform at the Draco PW facility that 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.

  • Lecture (Conference)
    Flash Radiotherapy and Particle Therapy Conference - FRPT 2022, 29.11.-02.12.2022, Barcelona, Spanien

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Publ.-Id: 36207