Background and Aims

Dosimetry for FLASH radiotherapy, VHEE radiotherapy as well as for laser-driven beams cause significant metrological challenges due to the ultra-high dose rates and pulsed structure of these beams, in particular for real time measurements with active dosimeters. It is not possible to simply apply existing Codes of Practice available for dosimetry in conventional external radiotherapy here. However, reliable standardized dosimetry is necessary for accurate comparisons in radiobiological experiments, to compare the efficacy of these new radiotherapy techniques and to enable safe clinical application. UHDpulse aims to develop the metrological tools needed for reliable real-time absorbed dose measurements of electron and proton beams with ultra-high dose rate, ultra-high dose per pulse or ultra-short pulse duration.

Methods

Within UHDpulse, primary and secondary absorbed dose standards and reference dosimetry methods are developed, the responses of available state-of-the-art detector systems are characterised, novel and custom-built active dosimetric systems and beam monitoring systems are designed, and methods for relative dosimetry and for the characterization of stray radiation are investigated.

Results

Prototypes of different active dosimetry systems show promising results for real-time dosimetry for particle beams with ultra-high pulse dose rates. The results of the UHDpulse project will be the input data for future Codes of Practice.

Conclusions

A brief overview of the progress in the UHDpulse project and the involved institutions will be given.

Acknowledgement: This project 18HLT04 UHDpulse has received funding from the EMPIR programme co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme.

Background and Aims

The Extreme Light Infrastructure (ELI) Beamlines is a state-of-the-art laser driven accelerator facility located in the Czech Republic. It will operate the most intense non-military laser system with ultra-high power up to 10 PW, concentrated plasma intensities of up to 10²⁴ Wcm^-2, and ultra-short laser pulses of the order of few femtoseconds. Lasers of a several hundred TWs are already capable of producing a large amount of ionizing radiation when interacting with suitable targets. Thus prompts the need for accurate dosimetry in ultra-short pulsed fields; this is a need shared with FLASH radiotherapy facilities alike. Solid-state detectors, such as Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) detectors are promising technique used for this purpose. They are immune to electromagnetic pulses and the liberated electron-hole pairs are trapped on a 10^-15 s to 10^-13 s timescale.

Methods

Within the compass of the 18HLT04 UHDpulse EMPIR project, TL and OSL detectors are irradiated in stray radiation fields at ELI Beamlines. Several luminescent materials are used. Exploiting different laser and experimental setups and different distances from the source, it is possible to investigate a wide range of dose rates.

Results

Detector responses are evaluated and compared to Monte Carlo expectations. Preliminary results are presented.

Conclusions

The results show how the irradiated luminescence dosimeters respond in complex radiation fields.

This project 18HLT04 UHDpulse has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme.