Reliability monitoring of medical accelerator

The reliability of the medical accelerators is required to be as high as possible. Because particle therapy accelerators (PTA) are more complex than Linac accelerators for conventional X-ray therapy, it is not easy to keep and maintain the stability. The standards of irradiation system have make a transition from the passive irradiation method to the scanning one. This means the connection between the accelerator system and the scanning irradiation system becomes stronger than that between the accelerator one and passive irradiation one. The displacement of the beam from the accelerator affects directly the position of the irradiation beam at the isocenter and may make the unexpected integrated dose distribution. So, the way to monitor the reliability of the PTA is required.\nWe proposed the way to monitor the reliability of PTA with parameters of Availability, Failure Rate and Repair time as a index for reliability monitoring. We introduced these monitoring parameter to the HIMAC (Heavy Ion Medical Accelerator in Chiba) including ion sources, linear accelerators, synchrotrons and irradiation system and has started to monitor its reliability since 2014.\nAll failures that occurred in a month have been listed with cause of failure, defective parts and downtime to calculate above parameters. If the trend of parameters shows low quality, the cause would be investigated and corrective action would be examined. This presentation will explain how we decided the parameters as reliability indexes and how we have used these, with the cycle of Monitor-Analysis-Correction- Evaluation that maintains and/or improves the accelerator reliability.56th Annual Conference of the Particl Therapy Co-Operative Group (PTCOG56