Development of clinically relevant QA procedures for the BrainLab ExacTrac imaging system

Area of Science:

• Medical Physics
• Radiological Imaging Technology

Background:

• The BrainLab ExacTrac (ET) system is crucial for accurate patient positioning in radiotherapy.
• Establishing robust Quality Assurance (QA) procedures is essential for maintaining the performance of imaging systems like the ET.
• TG 142 recommendations provide a framework for QA of planar kV imaging systems.

Purpose of the Study:

• To develop and implement Quality Assurance (QA) procedures for the BrainLab ExacTrac (ET) imaging system.
• To align the QA process with TG 142 recommendations for planar kV imaging.
• To establish a baseline for future image quality analysis and ensure system reliability.

Main Methods:

• Utilized a custom 3D-printed holder for precise phantom positioning at isocenter.
• Analyzed DICOM images using PIPSpro software to assess geometric distortion, spatial resolution (MTF), CNR, and noise.
• Measured beam quality and exposure using an Unfors R/F detector across various protocols, converting exposure to dose.

Main Results:

• Image quality parameters were comparable between the two ET X-ray tubes, allowing for a common baseline.
• Established baseline values for MTF (F50/F40/F30), noise, and CNR.
• Demonstrated high experimental reproducibility with measured phantom dimensions and kV values within acceptable tolerances.

Conclusions:

• A reliable QA process for the ET imaging system has been successfully implemented.
• The developed QA procedures characterize system performance at isocenter, aligning with clinical conventions.
• The established baseline and reproducible results ensure the ongoing accuracy and reliability of the ET imaging system.