Design of a personnel safety interlock system for proton therapy

Proton therapy is the most advanced radiotherapy approach in the world, and causes less damage to normal human tissue than traditional radiotherapy. Because the treatment process produces a high-energy proton beam, the personnel safety interlock system mainly considers measures to protect personnel from radiation hazards during beam preparation and the beam release process. Unlike other safety interlock systems, the personnel safety interlock system designed in this study focuses on the safety and stability of the system itself. The hardware and software of important interlock control loops are designed and developed according to the requirements of Safety Integrity Level 3 specified by IEC61508. A set of redundant ring networks was developed to ensure that damage to a certain network line does not affect the normal operation of the system. A set of friendly operation interfaces and data storage systems were developed to ensure that the operator can monitor the data in real time and trace the data. The personnel safety interlock system mainly includes a beam enabling function, clearance function, and emergency stop function. The system was put into actual use and successfully ensured personnel safety.