High-Energy, High-Dose Rate Radiation Generation for Advanced FLASH Radiobiology Studies

One of the research directions developed at ELI-NP focuses on pioneering experiments that utilize laser-driven radiation sources—particularly high-energy photons - to advance FLASH radiobiology research, with a special emphasis on studying biological samples' responses to ultra-high dose rate irradiation. Understanding cellular effects across the fundamental stages of radiation interaction—physical, chemical, and biological—demands ultra-short, high-dose-rate exposures. Recent advances in laser and plasma acceleration technologies have made this capability possible.

Traditional radiobiology has been limited to irradiation times ranging from microseconds to minutes, potentially impacting DNA repair processes and altering cellular responses. In contrast, our approach leverages ultra-short (femtosecond) high-dose irradiation, allowing us to study damage mechanisms at timescales that align closely with the DNA effects caused by free radicals generated by ionizing radiation.

Using high-power laser systems that reach focused intensities exceeding 10²² W/cm², we produce relativistic electrons through laser wakefield acceleration. These electrons, accelerated to GeV energies generate high-brightness, collimated gamma, and X-ray photons via mechanisms such as Betatron radiation, Bremsstrahlung, and Inverse Compton scattering. These photon sources, with femtosecond scale pulse durations, can deliver precise, single-shot doses in the Gy range, essential for simulating the conditions required for FLASH radiobiology. Through this method, we aim to enhance our understanding of differential cellular responses - particularly between cancerous and healthy cells - by closely replicating radiation effects at fundamental interaction timescales. This research represents a transformative approach in radiobiology, offering new insights into cellular responses to extreme dose rates and paving the way for therapeutic innovations.

Illustration of a cell exposed to laser-induced ionizing radiation

X-ray photodynamic therapy studies

The biomedical workgroup members are engaged in a range of cutting-edge activities, one of which focuses on X-ray assisted photodynamic therapy (PDT) as an innovative approach to cancer treatment. This initiative involves the development and optimization of photosensitizers that selectively target tumor cells, allowing for enhanced therapeutic efficacy. The team conducts extensive research to ensure these compounds can be effectively activated by X-ray irradiation, generating reactive oxygen species that induce localized cell death while minimizing damage to surrounding healthy tissue.

3D-printed irradiation setup featuring real-time dosimetry using two ionization chambers, alongside passive measurements with three OSLs, image plates, and RCF stacks

The irradiation setup is assisted by a Gradient Light Interference Microscopy (GLIM) system integrated with an AxioObserver 7 inverted microscope. This system, equipped with an incubator, fluorescence, and Differential Interference Contrast (DIC) capabilities, enables long-term live-cell imaging under controlled conditions. The use of Quantitative Phase Imaging (QPI) in the GLIM system is label-free, allowing us to observe and quantify cellular responses to radiation in real-time over prolonged periods, without the need for fluorescence labeling.

Images of B16 mouse melanoma cell line captured using an inverted Zeiss AxioObserver 7 microscope: (a) brightfield, (b) GLIM, and (c) GLIM combined with two fluorescence channels (DAPI and GFP).

This label-free imaging approach offers significant advantages over traditional fluorescence methods, reducing phototoxicity and allowing for continuous observation of cellular morphology and dynamics with high contrast and resolution. With this capability, we can gain deeper insights into radiation-induced cellular effects, track changes over time, and investigate the differential responses of cancerous and healthy cells in a physiologically relevant environment.

Development of immunotherapy-supported BNCT

The development of immunotherapy-supported BNCT at ELI-NP recently enlarged the portfolio of medical applications research. Currently, in vitro trials are being pursued to establish this new therapy for cancer treatment by a synergy of immunotherapy with radiologic Boron Neutron Capture Therapy (BNCT). The program is based on recent IFIN-HH - owned international patents developed at LDED and uses CRISPR - edited personalized immunocompetent cells as nanorobots for boron nanoparticles to selectively deliver boron nanoparticles to malignant cells, which then effectively act as a Trojan Horse in a successive radiologic treatment. The symbiosis between personalized Food & Drug Administration (FDA)-approved Immunotherapy & BNCT are compelling as it simultaneously enhances their unique features while irradicating their shortfalls in a synergetic approach.

Left: Boron loading of γδ CAR-T's, Right: BNCT on cellular level

Metabolomics analysis supported by advanced NMR

The ELI-NP Biophysics and Biomedical Applications laboratory and team develops research on the molecular effects of high dose-rate radiation in cells, tissue samples and organisms. The major goal of our research is to contribute new methods for the timely detection of the biological effects of FLASH radiation accelerated by high-power lasers, with dose rates up to Gy/ns. We intend to contribute to the widespread use of FLASH radiotherapy, as the Nuclear Magnetic Resonance-based methods we develop offer the possibility of rapid translation of research results from the laboratory to the clinic. To enhance magnetic resonance sensitivity, the first Dynamic Nuclear Polarization system in South-East Europe was recently installed in the Laboratory of Biophysics and Biomedical Applications. This recently-invented system (2003) increases the sensitivity of Nuclear Magnetic Resonance detection by factors > 10’000. A far-reaching application we pursue is the timely detection with increased sensitivity of the effects of combined treatments in oncology (radiotherapy, chemotherapy, immunotherapy), allowing the evaluation and optimization of treatment in real time.

Overview of developed research in Biophysics and Biomedical Applications Laboratory