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Impact of robust optimization on patient specific error thresholds for high dose rate prostate brachytherapy source
Dylan Koprivec1, Cedric Belanger2, Luc Beaulieu2
1Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, Australia.
Brachytherapy
|December 17, 2024
Summary
Patient specific error thresholds (PSETs) for high dose rate prostate brachytherapy (HDRPBT) were found to be equivalent across different inverse optimization methods. No single optimization approach significantly improved these thresholds, indicating robustness in HDRPBT planning.
Area of Science:
- Radiation Oncology
- Medical Physics
- Brachytherapy
Background:
- High dose rate prostate brachytherapy (HDRPBT) planning involves inverse optimization to achieve optimal dose distribution.
- Catheter shift errors can impact treatment efficacy and toxicity, necessitating the determination of patient-specific error thresholds (PSETs).
Purpose of the Study:
- To compare the impact of catheter shift errors on different HDRPBT plans.
- To determine patient-specific error thresholds (PSETs) for HDRPBT plans generated using various inverse optimization techniques.
Main Methods:
- Fifty HDRPBT patients' plans were analyzed, with three distinct optimization methods applied: original Oncentra Prostate, graphical processor unit multi-criteria optimization (gMCO), and gMCO with a robustness parameter (gMCOr).
- PSETs were calculated using specialized catheter shift software.
- gMCO and gMCOr plans were selected from a pool of 2000 Pareto optimal plans based on dose-volume histogram (DVH) criteria.
Main Results:
- All optimized plans met the clinical DVH criteria, with gMCO and gMCOr plans showing improved dose distributions compared to the original plan.
- No single optimization method consistently demonstrated superior PSETs across all shift directions.
- The inclusion of a robustness parameter in gMCOr did not significantly impact PSETs or plan optimization outcomes.
Conclusions:
- Patient-specific error thresholds (PSETs) for HDRPBT are equivalent irrespective of the inverse optimization method employed.
- Current inverse optimization techniques do not significantly enhance PSETs, suggesting a plateau in achievable error tolerance improvements.
