The Heavy Ion Medical Accelerator in Chiba (HIMAC), a heavy ion radiotherapy device of the National Institutes for Quantum Science and Technology (QST), is the first dedicated machine for heavy ion cancer therapy in the world. Beam stop due to device failure add a burden and excess amount of radiation to the patient because of retry of the patient positioning. However a preventive maintenance is indispensable so as not to bring such situation, it is not so easy because of deterioration of HIMAC, budget constraint and so on.
Accelerator Engineering Corporation (AEC) is a company that supports the operation and maintenance of heavy ion medical accelerators in Japan including HIMAC, and we carry out various maintenance work to produce the stability and reproducibility of the beam. QST and AEC organized "Maintenance Program (MP)" team in 2011, and review the utilization of fault history data. MP team analyzed those statistics in detail, and set priority to the problems which should be solved in order to improve the reliability and availability of HIMAC.
Present status, availability and MP procedures will be presented.