For the past few years, Dr. Kim has been conducting research on risk assessment and process improvement in radiation oncology. Prospective risk assessment (example, FMEA) performed for the radiosurgery special procedure and identified the potential risks and improved the clinical procedure based on the research result. Also another branch of her research for risk assessment was the incident learning system. The summary of this research was our incident learning system, which enabled real-time tracking of errors in the radiation oncology clinic, and were useful and practical means of improving safety and quality in patient care. Regarding the process improvement, Six-Sigma was applied within a structured DMAIC model to improve the QA process. Research demonstrated how to analyze the process capability and how to determine which variable to target when tolerances had to be established for the QA process.