Perspectives for effective applications of laser-driven Very High Energy Electrons in medicine and biology

L. Labate, D. Palla, D. Panetta, M. Avella, F. Baffigi, F. Brandi, F. Di Martino, L. Fulgentini, A. Giulietti, P. Koester, D. Terzani, P. Tomassini, C. Traino, L.A. Gizzi

Proceedings SPIE 11790,1179009 (2021), Applying Laser-driven Particle Acceleration II, Medical and Nonmedical Uses of Distinctive Energetic Particle and Photon Sources: SPIE Optics + Optoelectronics Industry Event

Abstract

The direct use of so-called Very High Energy Electrons for radiotherapy is currently deserving a renewed and growing attention. This is mostly due to the recent emergence of the so-called FLASH effect in radiobiology [1], consisting in a surprising reduction of adverse effects on healthy tissue by ionizing radiation when dose delivery occurs at very high average dose rates (greater than a few tens of Gy/s). In order for a real clinical translation of this new protocol in the clinical practice, the development of novel kind of ionizing radiation sources featuring such very high dose rates, which are basically hindered by the relatively low Bremsstrahlung conversion efficiency in current machines, is considered as an essential step. With this respect, laser-driven accelerators of Very High Energy Electron (VHEE) beams, with energy in the range 100-250 MeV, are regarded as one of the most promising tool [2]. Furthermore, both early studies, dating back to 1990s, and more recent works suggest that an improved dose deposition pattern can be expected from electron beams, as compared to photon beams, when the very high energy region is reached. In this talk, we report on a recent experiment aimed at assessing dose deposition for deep seated tumors using advanced irradiation schemes, typical of current radiotherapy protocols, with an existing laser-driven VHEE source [3]. In particular, our measurements showed control of localized dose deposition and modulation, suitable to target a volume at depths in the range from 5 to 10 cm with mm resolution. Based on this experimental findings and on further numerical simulations, we also discuss the features and potentialities of laser-driven VHEE sources for radiobiology experiments aimed at deepening the understanding of the mechanisms underpinning the FLASH effect. The main requirements and the perspectives for a longer term translation of an electron-based radiotherapy into the real clinical practice will be also addressed. [1] M.-C. Vozenin et al., Biological Benefits of Ultra-high Dose Rate FLASH Radiotherapy: Sleeping Beauty Awoken, Clin. Oncol. 31 (2019), 407 [2] A. Giulietti (Eds), Laser-Driven Particle Acceleration Towards Radiobiology and Medicine, Springer (2016) [3] L. Labate et al., Toward an effective use of laser‐driven very high energy electrons for radiotherapy: Feasibility assessment of multi‐field and intensity modulation irradiation schemes, Sci. Rep. 10 (2020), 17307