Benchmarking Monte-Carlo dose calculation for MLC CyberKnife treatments

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• Vendor-independent Monte Carlo (MC) dose calculation (IDC) is crucial for patient-specific quality assurance in multi-leaf collimator (MLC) based CyberKnife treatments.
• Benchmarking and validation of the commercial MC dose calculation engine (Precision MC) integrated into the CyberKnife treatment planning system are essential.

Purpose of the Study:

• To benchmark and validate the Precision MC dose calculation engine against an IDC framework for MLC-based CyberKnife treatments.
• To assess the accuracy and efficiency of Precision MC for patient-specific quality assurance.

Main Methods:

• Dose profiles and depth dose curves in water for various MLC-shaped fields were compared between IDC, Precision MC, and measurements.
• Dose distributions for phantom and clinical lung cases were calculated using both IDC and Precision MC.
• Quantitative comparisons included dose-volume parameters and 3D gamma analysis with 2%/1mm criteria.

Main Results:

• Precision MC showed agreement with IDC within 3.1% or 1mm for dose profiles and 2.3%/1mm for depth dose curves.
• Mean PTV doses differed by -1.0% to +2.3% between IDC and Precision MC, with gamma passing rates >98.1%.
• Precision MC calculation times ranged from 2.2 to 8.1 minutes, significantly faster than IDC's 4-6 hours.

Conclusions:

• Precision MC demonstrates both accuracy and efficiency for MLC-based CyberKnife M6 system planning.
• The study validates Precision MC against an established MC-based IDC framework.
• Precision MC is currently utilized in clinical practice for patient treatment planning.