Topas Monte Carlo Simulation and Patient-Specific Cherenkov Dose Comparison for External Beam Radiation Therapy
Abstract
Purpose
Cherenkov imaging has emerged as a promising technique for real-time dosimetry during external beam radiation therapy (EBRT); however, quantitative conversion of Cherenkov signal to delivered radiation dose remains challenging. The purpose of this study is to evaluate the agreement between TOPAS Monte Carlo–simulated dose and clinically planned dose from the Aria treatment planning system using water and solid phantom measurements, and to investigate the feasibility of converting patient-specific Cherenkov dose to delivered radiation dose through TOPAS-based correction methods.
Methods
Water and solid phantom experiments were performed to acquire Cherenkov images under multiple beam delivery conditions, including variations in gantry angle, jaw size, and MLC patterns. Corresponding TOPAS Monte Carlo simulations were conducted using clinical beam parameters, and simulated dose distributions were compared with clinically planned dose from the Aria treatment planning system. For patient studies, TOPAS simulations were performed using patient-specific treatment parameters, and surface-based comparisons between measured Cherenkov dose and simulated dose were used to explore correction curves for Cherenkov-to-dose conversion.
Results
TOPAS-simulated dose showed good agreement with measured dose in both water and solid phantom studies. Consistent agreement between TOPAS-simulated dose and clinically planned dose from the Aria treatment planning system was observed in solid phantom measurements across different gantry angles, jaw settings, and multi-leaf collimator (MLC) configurations. Patient-specific comparisons demonstrated a correlation between Cherenkov-derived dose and TOPAS-simulated dose, supporting the feasibility of establishing a correction relationship between Cherenkov signal and delivered radiation dose.
Conclusion
TOPAS-simulated dose agreed with phantom measurements and Aria planned dose across beam conditions. Patient-specific Cherenkov-derived dose correlated with TOPAS predictions, supporting conversion of Cherenkov signals to delivered dose using TOPAS-based correction. Results demonstrate the potential of Cherenkov imaging as a quantitative, real-time dosimetry tool for external beam radiation therapy.