New real-time monitoring technique promises enhancements for next-generation radiotherapy

EuPRAXIA DN Fellow David Gregocki conducted an experiment involving researchers from the National Institute of Optics (CNR) in Pisa, the University of Pisa, and the National Institute of Nuclear Physics (INFN) in Pisa to unveil a promising new method for real-time dose monitoring in laser-driven electron beam experiments. Their findings, published in the journal Instruments under the title “Real-Time Dose Monitoring via Non-Destructive Charge Measurement of Laser-Driven Electrons for Medical Applications,” could mark an important step toward advancing next-generation radiotherapy systems.

Graphical scheme of the ICT enclosure used in the experiment designed in open-source software Blender®

The study focuses on laser-driven Very High Energy Electron (VHEE) beams characterized by their kinetic energy in the range of approximately 50 to 300 MeV, which are being actively explored for use in radiotherapy, particularly in the so-called “FLASH” regime. FLASH radiotherapy delivers ultra-high dose rates that can kill tumour cells while sparing surrounding healthy tissue. Given the ultra-high dose rates and its medical application, one of the field’s key challenges is the development of non-destructive beam diagnostics capable of providing real-time response.

To address this, the researchers developed a monitoring system capable of measuring both the charge and dose of the electron bunches that strike a target without interrupting or damaging the beam. The system relies on an Integrating Current Transformer (ICT) paired with RadioChromic Films (RCFs), allowing it to record charge and dose data simultaneously. By establishing an analytical relationship between the charge and the delivered dose using both experimental measurements and Monte Carlo simulations, the team demonstrated that, for thin samples, those thinner than the penetration depth of the electrons produced in the experiment, the dose is approximately proportional to the electron charge. As a result, ICTs, which are normally used for charge measurements, can serve as non-destructive dose-measuring devices as well. While the results were averaged over several shots, future development aims to achieve single-shot dose monitoring, requiring more sensitive detectors than the radiochromic films currently used.

These results provide a potential step toward the future of FLASH radiotherapy in both preclinical studies and future clinical systems based on laser-driven VHEE beams. Beyond medical applications, the technology could also benefit research fields that focus on real-time beam characterization and monitoring.

You can access the full paper here.