Quantifying clinical severity of physics errors in high-dose rate prostate brachytherapy using simulations.

Area of Science:

• Medical Physics
• Radiation Oncology
• Brachytherapy

Background:

• High-dose rate prostate brachytherapy (HDRPB) relies on precise planning and delivery.
• Physics errors can potentially compromise treatment efficacy and patient safety.
• Failure Modes and Effects Analysis (FMEA) is a common tool for identifying potential risks.

Purpose of the Study:

• To quantitatively assess the clinical significance of potential HDRPB physics errors using automated simulations.
• To evaluate the impact of various error types on key dose metrics for prostate, urethra, and rectum.

Main Methods:

• A comprehensive list of HDRPB failure modes was generated and scored by physicists using the Risk Priority Number (RPN) method.
• Simulations included single and systematic catheter shifts, digitization errors, and catheter swaps.
• Deviations in prostate D90%, urethra D20%, and rectum D1cm³ were analyzed against thresholds for clinical impact.

Main Results:

• Twenty-nine failure modes were identified, with RPNs varying significantly across observers.
• Systematic shifts >0.4 cm and digitization errors >0.3 cm (urethra) or >0.4 cm (rectum) led to potentially reportable events.
• Catheter swaps and smaller systematic shifts/digitization errors also demonstrated potential clinical impact.

Conclusions:

• Automated simulations provide valuable insights into the clinical impact of HDRPB physics errors.
• Significant variability exists in expert scoring of failure modes.
• Simulation-based analysis can enhance traditional FMEA by quantifying error severity.