Characteristics of a Very High Energy Electron Beam in a Laser Wakefield Accelerator for Cancer Therapy

A cancer treatment device using a very high energy electron beam has been studied as a new radiation therapy method because of its deep penetration depth, dose characteristics that are better than those of the existing X-ray method, and easy adjustment of the irradiation direction compared to existing equipment. For this treatment, compact high-energy electron accelerators are essential, and a laser wakefield accelerator is a good candidate. In this study, very high energy electrons were accelerated using a laser wakefield accelerator, and the dose characteristics due to these electrons were measured to confirm the possibility of treatment. Electron beam with an energy of 94 MeV were accelerated by using a 16-TW high-power laser, and the dose profile was measured with a tough phantom by using a Gafchromic film. With an 18 nC charge, the peak dose was 120 cGy at a 40 mm depth. The measured dose profile was compared with that obtained using a Monte Carlo simulation with low and high energy electron beams, and the results indicate a quasi-mono-energetic property of the electron beam.