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In our institution, we installed MRI-guided radiotherapy system (MRIdian, ViewRay Inc.), allowing to perform on-line adaptive radiotherapy (ART). The MRIdian has three 60 Co sources with 120 degrees apart, equipped with MRI system using a static magnetic field of 0.35 T. The tumor can be monitored and identified in real-time Cine-MRI during treatments, and gated-radiotherapy is possible based on the boundaries. On-line ART can provide the optimum delivery where high dose coverages to the tumor and sparing dose to health organs can be achieved. However, patient specific QA in on-line ART has a limitation of activities, because patients stay in the couth while planning. In this report, we summarized the commissioning of the MRIdian, and the patient specific QA established in on-line ART was described.

Advanced radiotherapy such as intensity-modulated radiotherapy offers many advantages of high accuracy and efficiency of radiotherapy. To date, many technical guidelines with description of quality assurance and quality control have been reported. However, some reports indicated that human factor and environment is major cause of radiotherapy incidents. If radiotherapy systems depend on automation and computer system, individual risk management is degraded and ability of preventing radiotherapy incidents weaken. Recently, the American Association of Physicists in Medicine (AAPM) task group-100 was reported and it has a new concept guideline, which proposed the comprehensive risk management and education of non-technical skills for overall radiotherapy processes. The TG-100 recommends implementation of process map, reporting system, risk assessment such as failure mode and effects analysis (FMEA) and fault tree analysis (FTA) especially for advanced radiotherapy. In this paper, we described effective and efficient procedures to improve the treatment processes and education of non-technical skills using the such management tools proposed by the TG-100 guide-lines.