Dosimetric characterization of the laser-accelerated high-energy electron beam for radiotherapy applications

Radiotherapy utilizing very-high-energy electron (VHEE) beams in the range of 50–300 MeV has gained significant interest over the past two decades due to their advantageous dose characteristics, deep tissue penetration capabilities, and potential for ultrahigh dose-rate treatments. Laser wakefield accelerators (LWFAs) are particularly well suited for generating VHEE beams in a compact setup, thanks to their substantially higher accelerating gradients compared to conventional radio-frequency accelerators. To meet the demands of clinical applications, a comprehensive dosimetry study of LWFA-generated VHEE beams in a preclinical treatment configuration is essential. In this study, a VHEE beam with a maximum energy over 160 MeV was produced using a compact and stable LWFA prototype operating at 1 Hz. The beam was subsequently transported through a quadrupole triplet to eliminate low-energy components and reduce pointing jitter, followed by a scatterer and collimator to create a uniform circular radiation field with an 8-mm diameter. Using this beam, we measured the three-dimensional dose distribution within a solid-water phantom and evaluated the feasibility of multifield intensity-modulated irradiation by delivering 400 VHEE beams from 20 different angles into the phantom. This resulted in a 16-mm-diameter dose plateau peak, with the relative uniformity of approximately 2.8%, and the entrance dose was only 20% of the peak value. These findings demonstrate the feasibility and robustness of LWFA-based VHEE beams for treating deep-seated tumors, highlighting the need for dedicated engineering and preclinical studies in this promising direction.