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A novel system for commissioning brachytherapy applicators: example of a ring applicator
Gabriel P Fonseca1, Michiel R Van den Bosch1, Robert Voncken1
1Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Dr. Tanslaan 12, Maastricht 6229 ET, Netherlands.
Physics in Medicine and Biology
|September 16, 2017
Summary
A new imaging system enhances quality assurance for high dose rate (HDR) brachytherapy applicators. It accurately measures dwell positions and times using the HDR 192Ir source, improving safety and efficiency in radiation therapy.
Area of Science:
- Medical Physics
- Radiation Oncology
- Medical Imaging
Background:
- Brachytherapy requires precise applicator positioning for effective radiation delivery.
- Current quality assurance (QA) methods for high dose rate (HDR) brachytherapy applicators can be time-consuming and may lack precision.
- Ensuring accurate dwell times and positions is critical for optimal patient outcomes and minimizing side effects.
Purpose of the Study:
- To develop and evaluate a novel imaging system for improving the commissioning and QA of HDR brachytherapy applicators.
- To enable real-time verification of dwell positions and times during brachytherapy procedures.
- To assess the system's accuracy in measuring inter-dwell distances under various conditions.
Main Methods:
- An imaging panel and an HDR 192Ir source were used to generate reference and dwell position images of brachytherapy applicators.
- Gamma photons from the 192Ir source were utilized for both applicator imaging and dwell position verification.
- In-house developed software processed imaging data in real-time, enabling analysis of dwell positions, times, and applicator geometry.
Main Results:
- The novel system accurately verified dwell positions and times, with standard deviations for reproducible positions below 0.05 cm.
- One applicator exhibited intermittent positional deviations up to 0.3 cm, highlighting the system's ability to detect subtle errors.
- Transfer tube curvature introduced positional differences greater than 0.1 cm, while applicator inclination had a negligible effect.
Conclusions:
- The developed imaging system provides accurate, real-time verification of HDR brachytherapy applicator irradiation procedures.
- It enhances QA by precisely measuring dwell positions and times, including small inter-dwell distances (≤0.1 cm).
- The system reduces measurement time and eliminates the need for an additional radiation source, utilizing the existing HDR 192Ir source.
