Development of laser accelerated ion beams for radiation therapy

C-M Ma, E Fourkal, I Veltchev, JS Li, W Luo, J Fan and T Lin

Radiation Oncology Department, Fox Chase Cancer Center, 333 Cottman Av, Philadelphia, PA 19111, USA, Phone: 1-215-728-2996, Fax: 1-215-728-4789, Email: charlie.ma@fccc.edu

Recent advances in laser technology have made proton (light ion) acceleration possible using laser induced plasmas. In this work, we report our work on the investigation of a new proton therapy system for radiation oncology, which employs laser-accelerated protons. If successfully developed, the new system will be compact, cost-effective and capable of delivering energy- and intensity-modulated proton therapy (EIMPT). We have focused our research on three major aspects: (1) target design for laser-proton acceleration, (2) system design for particle/energy selection and beam collimation, and (3) dosimetric studies on the use of laser-accelerated protons for cancer therapy. We have performed particle-in-cell (PIC) simulations to investigate optimal target configurations for proton/ion acceleration. We also performed Monte Carlo simulations to study the beam characteristics and the feasibility of using such beams for cancer treatment. A fast dose calculation algorithm has been developed for pre- and post-optimization dose calculation. Since laser-accelerated protons have broad energy and angular distributions, which are not suitable for radiotherapy applications directly, we have designed a compact particle selection and beam collimating system for EIMPT beam delivery. We also proposed a new gantry design to make the whole system compact and easy to operate. We have compared Monte Carlo calculated dose distributions using photon IMRT, conventional proton beams and EIMPT. Our results show that EIMPT using laser protons provided identical plan quality as conventional protons with superior target coverage and much reduced critical structure dose and integral dose. EIMPT is more dosimetrically advantageous than photon IMRT or conventional proton beams.