AAPM Medical Physics Practice Guideline 8.b: Linear accelerator performance tests

Quality assurance in radiation therapy is essential for ensuring accurate and safe treatment delivery. Prior research has shown that linac QA programs must evolve to match clinical practices and new technologies. However, no prior work had resolved how to tailor tests to specific clinical use patterns. This gap motivated the AAPM to update its guidance. The original report lacked clarity on how to incorporate new linac components into QA testing. That uncertainty drove the need for revised performance criteria. No standardized approach existed for prioritizing tests based on clinical risk. This lack of consensus hindered consistent QA implementation across institutions. The AAPM recognized the need for a structured, evidence-based guideline. The committee aimed to address these limitations by aligning tests with clinical relevance and safety.

This guideline aims to provide a structured framework for selecting linac performance tests that align with clinical use and safety. The goal is to assist QMPs in developing QA programs that reflect current practices. The committee sought to identify tests that detect errors relevant to specific treatment scenarios. The original report did not address newer linac features, such as advanced imaging systems. The updated guideline fills this gap by incorporating recent technological changes. The committee evaluated existing QA recommendations to determine necessary modifications. The purpose also includes defining how to establish reference data for performance monitoring. The guideline emphasizes collaboration with vendors to ensure tests are practical and effective.

The committee reviewed current QA recommendations to identify outdated or insufficient tests. They assessed new linac components that have become standard in clinical practice. Tests were grouped by category, such as dosimetry and mechanical performance. Each test was evaluated for its relevance to patient safety and clinical outcomes. The committee prioritized tests based on their impact on treatment accuracy and risk. Implementation notes were added to clarify the purpose and method of each test. Vendor collaboration was encouraged to ensure tests are compatible with equipment upgrades. The final list was selected through consensus to reflect a balanced and comprehensive approach.

The guideline proposes a categorized list of performance tests for linacs, grouped by clinical relevance and safety impact. Dosimetry tests were emphasized for their role in ensuring accurate radiation delivery. Mechanical tests were included to detect misalignments affecting treatment precision. Tests for imaging systems were added to reflect their growing use in treatment planning. Reference data acquisition methods were standardized to ensure consistency across institutions. The committee recommended routine isocenter verification to maintain machine accuracy. Tests after maintenance and upgrades were emphasized to prevent post-service errors. Implementation notes were provided to guide QMPs in executing each test effectively.

The updated guideline provides a structured approach for QMPs to develop linac QA programs that align with clinical use and safety. The committee emphasized the importance of tailoring tests to specific treatment scenarios. The inclusion of new components reflects the evolving nature of linac technology. The prioritization of tests based on risk ensures that critical issues are addressed first. The guideline encourages collaboration with vendors to enhance test feasibility and effectiveness. Implementation notes help QMPs understand the purpose and execution of each test. The committee acknowledged that institutions must adapt tests to their own clinical practices. The ultimate responsibility for QA program implementation remains with the QMP.