Quantitative Approach to Failure Mode and Effect Analysis for Linear Accelerator Quality Assurance.

Area of Science:

• Medical Physics
• Radiation Oncology
• Quality Assurance

Background:

• Radiation therapy relies on linear accelerators (LINACs) for precise cancer treatment.
• Quality Assurance (QA) protocols, such as TG-142, are essential for ensuring LINAC performance and patient safety.
• Current QA test frequencies may not be optimized for physicist time efficiency or risk reduction.

Purpose of the Study:

• To determine optimal clinic-specific linear accelerator (LINAC) quality assurance (QA) TG-142 test frequencies.
• To maximize physicist time efficiency while maintaining high patient treatment quality.
• To apply a quantitative approach to risk assessment for LINAC QA tests.

Main Methods:

• A novel quantitative failure mode and effect analysis (FMEA) was employed.
• Nine LINAC-years of QA records were analyzed for failure occurrence rates.
• Test failure severity was modeled by simulating errors in intensity modulated radiation therapy (IMRT) treatment plans.

Main Results:

• Output and laser testing showed the highest failure occurrence rates.
• Imaging QA tests (isocenter and positioning) had the greatest failure severity.
• Recommended frequencies: daily for output/lasers, weekly for imaging, biweekly for ODI/jaws vs. light field.

Conclusions:

• Failure mode and effect analysis (FMEA) is valuable for prioritizing LINAC QA tests based on risk.
• The proposed testing frequencies balance QA effectiveness with practical time constraints.
• This risk-based approach optimizes QA for non-stereotactic radiosurgery/stereotactic body radiation therapy LINACs.