Commissioning Monte Carlo algorithm for robotic radiosurgery using cylindrical 3D-array with variable density...

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Imaging

Background:

• Commissioning the Monte Carlo (MC) algorithm for the CyberKnife (CK) robotic stereotactic system is crucial for accurate treatment planning.
• Patient-specific quality assurance (QA) is essential for verifying treatment accuracy in stereotactic body radiation therapy (SBRT).

Purpose of the Study:

• To commission the MC-based model of the CyberKnife system.
• To evaluate the feasibility of patient-specific QA using the ArcCHECK (AC) cylindrical 3D-array with Multiplug (MP) inserts.

Main Methods:

• Developed and validated an MC model for the CK system.
• Utilized the AC with MP inserts for both simple beam setup and patient-specific QA scenarios.
• Compared MC model results against the RayTracing (RT) algorithm using gamma index criteria (e.g., 3%/1mm, 2%/2mm).

Main Results:

• The MC-based model demonstrated superior performance compared to the RT algorithm for both simple and patient-specific QA tasks.
• Mean gamma index differences were minimal for simple beam setups across different MP configurations.
• Patient-specific QA with lung inserts showed significant differences between MC and RT, with MC generally achieving higher passing rates (e.g., 90.5% vs. 82.3% for 2%/2mm in single lung insert setup).

Conclusions:

• The ArcCHECK with Multiplug is a feasible tool for comprehensive commissioning and patient-specific QA of the CyberKnife MC algorithm for SBRT.
• While MC calculations showed superior results, accuracy may be limited by the Multiplan system's material library.
• The findings are comparable to other reported commissioning measurements for flattening filter-free (FFF) beams.