Generation and comparison of 3D dosimetric reference datasets for COMS eye plaque brachytherapy using model-based...

Area of Science:

• Medical Physics
• Radiation Oncology
• Brachytherapy

Background:

• The current standard for brachytherapy dose calculation is the AAPM TG-43 formalism.
• A transition to model-based dose calculation algorithms (MBDCAs) is underway.
• There is a need for standardized test cases to validate MBDCAs.

Purpose of the Study:

• To establish the first set of test cases for low-energy photon-emitting brachytherapy using MBDCAs.
• To facilitate the adoption of MBDCAs in clinical practice.
• To support the transition from TG-43 to MBDCAs.

Main Methods:

• Five distinct test cases were developed, including single seeds, multiple seeds, and eye plaques in water and phantom environments.
• Calculations were performed using four Monte Carlo (MC) codes and a research treatment planning system (TPS).
• Dose distributions and input files are publicly available for reproducibility.

Main Results:

• MC codes demonstrated good agreement (local agreement within ~2.5%, global within ~2%).
• The research TPS showed varying agreement with MC codes, ranging from within 5% to ~20% locally and 0.4% to 10% globally.
• The developed test cases provide a benchmark for MBDCA validation.

Conclusions:

• The established test cases can support the commissioning of MBDCAs for low-energy brachytherapy.
• This work provides a framework for developing similar test cases for other brachytherapy applications.
• The findings align with recommendations from AAPM TGs 186 and 221 and AAPM Report 372.