Evaluation of the truebeam machine performance check (MPC): mechanical and collimation checks

Area of Science:

• Medical Physics
• Radiation Oncology
• Quality Assurance

Background:

• TrueBeam linear accelerators require regular performance verification.
• Traditional quality assurance (QA) methods can be time-consuming.
• Automated tools like Machine Performance Check (MPC) offer potential for efficient QA.

Purpose of the Study:

• To evaluate the performance of MPC's geometric tests for TrueBeam linacs.
• To assess MPC's accuracy in verifying beam collimation (MLC, jaws) and mechanical systems (gantry, collimator).
• To compare MPC's results with routine departmental QA tests.

Main Methods:

• Compared MPC's Multi-Leaf Collimator (MLC) tests against Picket Fence analysis.
• Compared MPC's jaw position checks against EPID-based methods, light field/graph paper, and Daily QA3.
• Compared MPC's gantry and collimator checks against spirit level and Picket Fence analysis.
• Assessed MPC's sensitivity by introducing deliberate calibration errors.

Main Results:

• MPC MLC tests agreed with Picket Fence analysis within 0.3 mm.
• MPC jaw checks agreed with in-house EPID measurements within 0.2 mm.
• All MPC parameters demonstrated accurate sensitivity to introduced calibration errors.
• MPC results showed good agreement with established routine QA procedures.

Conclusions:

• Machine Performance Check (MPC) is a suitable automated tool for daily QA of TrueBeam linacs.
• MPC accurately verifies geometric and beam collimation performance.
• MPC demonstrates reliability and sensitivity for quality assurance in radiation oncology.