An electronic portal image device (EPID)-based multiplatform rapid daily LINAC QA tool

Area of Science:

• Medical Physics
• Radiation Oncology
• Quality Assurance

Background:

• Daily quality assurance (QA) is critical for multiplatform linear accelerators (LINACs).
• Existing QA tools may be time-consuming or costly, especially for institutions with limited resources.
• The need for an efficient and economical daily quality research tool (DQRT) for LINACs is evident.

Purpose of the Study:

• To develop an efficient and economic daily quality research tool (DQRT) for LINACs.
• To utilize an Electronic Portal Image Device (EPID) for daily checks of both flattening filter (FF) and flattening filter-free (FFF) photon beams.
• To provide a cost-effective QA solution for radiation therapy.

Main Methods:

• EPID calibration followed by analysis of monitored parameters from open and wedge portal images.
• Verification of EPID position accuracy, long-term stability, and linearity between image gray value and exposure.
• Evaluation of output and beam quality stability for 6-MV FF and FFF beams, including introduced setup errors, and comparison with commercial QA tools (FC65-G, Matrixx).

Main Results:

• All monitored parameters demonstrated excellent repeatability.
• A strong linear correlation was observed between EPID image grayscale values and exposure.
• The DQRT showed negligible differences compared to FC65-G and Matrixx, with consistent results over a 2-month evaluation period on three LINACs.

Conclusions:

• The developed DQRT is a time-efficient and effective tool for daily LINAC QA.
• It provides QA results comparable or superior to traditional methods, with richer data.
• The DQRT presents a viable, economical alternative for hospitals with limited QA time or budget constraints.