Research and application of chromatic effect in laser-driven proton therapy

Abstract

Based on the rapid development of ultra high-power laser technology and due to the urgent need for miniaturized particle radiotherapy accelerator construction, compact laser accelerators have been studied as a research focus. The collection of the beam with large divergence angle and the selection of beam energy spread from initial generated beam are core issues in the design of laser accelerator. Chromatic effect is an effective method of energy selection while collecting beam. However, it is found that the nonlinear effect introduced by the actual edge field of a strong magnetic field and the special beam distribution produced by laser acceleration directly affect the energy selection. Based on the design of CLAPA-II, we analyze chromatic effect of energy selection by combining the 3-D strong magnetic field of particle collecting solenoid and the initial particle library of laser acceleration generated by PIC. We further propose a more compact laser-driven proton therapy design using the chromatic effect and energy reducer. And we research a broad-spectrum treatment planning system corresponding to it. It can effectively reduce proportion of low energy particles and complete energy selection after considering nonlinear effect of high 3-D magnetic field and special initial distribution. This can be applied in the design of gantry, which can be lighter than the traditional gantry. And for head, neck, and lung tumor models, dose delivery can be completed in 10 min and 20 min.