Technical Note: A feasibility study of using the flat panel detector on linac for the kV x-ray generator test

Area of Science:

• Medical Physics
• Radiological Imaging
• Quality Assurance

Background:

• Linear accelerators (linacs) are crucial in radiation therapy.
• Accurate performance evaluation of x-ray generators is essential for patient safety and treatment efficacy.
• Traditional quality assurance (QA) methods may involve inefficiencies and variability.

Purpose of the Study:

• To assess the feasibility of employing an integrated kV flat panel detector on a linac for consistency evaluations of kV x-ray generator performance.
• To establish a novel, automated approach for routine QA of x-ray generators.

Main Methods:

• An in-house designed aluminum (Al) array phantom with varying thicknesses was utilized.
• XML script-driven image acquisition captured kV images with diverse settings.
• Image quality metrics (ROI mean intensity, SD, NPS) assessed tube voltage accuracy, exposure accuracy, and linearity against baseline curves.
• Method robustness was validated on two linacs over three months.

Main Results:

• Tube voltage accuracy verified with 2% tolerance and 2 kVp intervals for 40 kVp settings.
• Exposure accuracy tested with 4% consistency tolerance across 40 kVp and three mAs settings.
• Exposure linearity achieved a coefficient of variation (CV) of 0.1 for three mAs settings.

Conclusions:

• A novel, automated method for x-ray generator testing using an on-board kV flat panel detector on linacs was proposed.
• This approach mitigates inefficiencies and variability linked to third-party QA detectors.
• The integrated method enhances consistency and automation in radiological QA processes.