A quality assurance tool for high-dose-rate brachytherapy.

Area of Science:

• Medical Physics
• Radiation Oncology
• Medical Imaging

Background:

• High-dose-rate (HDR) brachytherapy requires precise quality assurance (QA) for accurate radiation delivery.
• Current QA methods for verifying source positioning and dwell times can be time-consuming.
• Ensuring the accuracy of dwell positions and durations is critical for patient safety and treatment efficacy.

Purpose of the Study:

• To develop a novel QA tool for HDR brachytherapy.
• To enable rapid and accurate verification of both dwell positions and dwell times.
• To improve the efficiency of pretreatment QA procedures in brachytherapy.

Main Methods:

• A QA tool was constructed combining radiochromic film for position verification and photodiode detectors for dwell time verification.
• Temporal accuracy was characterized using light-emitting diodes coupled to photodiode detectors.
• The tool was validated on a commercial brachytherapy afterloader, with dwell time measurements independently verified by an optical camera.

Main Results:

• The QA tool demonstrated a temporal accuracy of approximately 1 ms.
• Source positions were visually assessed within 0.5 mm, and film scanning improved accuracy to 0.2 mm.
• The tool identified significant biases in dwell time (exceeding 60 ms) and large standard deviations (30 ms) in a commercial afterloader.

Conclusions:

• The developed QA tool significantly reduces pretreatment verification time to about 6 minutes.
• This tool provides a rapid and effective method for verifying critical treatment parameters in HDR brachytherapy.
• The findings highlight the importance of comprehensive QA for identifying potential inaccuracies in brachytherapy delivery systems.