An advanced beam energy control strategy for medical cyclotron via ADRC with model-based feedforward controller.

Medical cyclotron is the critical component for radiation therapy, which provides state-of-the-art treatment platform for cancer therapy. The energy stability of the beam is one of the most critical problem during the startup procedure or the long-term operation. Traditional beam energy control adopts open-loop regulation or proportional-integral-derivative (PID) control which does not depend on mathematical model. The classical PID control strategy has many problems for long-term operation, such as the unstable and imprecise control response due to its simple calculation. In this research, a nonlinear beam energy feedback control system (BEFS) mathematical model is established based on mechanism method. Based on it, an active disturbance rejection control strategy (ADRC) strategy is proposed to improve the response speed, control accuracy and disturbance rejection ability of the BEFS. In addition, a model-based feedforward controller is designed to enhance the controller's performance. Simulation results demonstrate that the proposed strategy, which has the better anti-disturbance capability and response speed, makes better beam energy tracking performance than traditional ADRC strategy and PID control strategy.