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Updated: Mar 12, 2026
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Published on: July 25, 2025
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Modeling the Agility head of the VersaHD accelerator and its beam profile by Geant4: Logfile-based geometry
Le Van Tinh1, Phan Viet Cuong2, Nguyen Van Kien3
1Vietnam National Cancer Hospital, 30 Cau Buou, Thanh Liet, Hanoi, Viet Nam; Nuclear Training Center, VINATOM, 140 Nguyen Tuan, Hanoi, Viet Nam.
Summary
A new Monte Carlo simulation code for the Elekta Agility head was developed. This validated tool enhances patient-specific quality assurance (PSQA) in radiation therapy by recalculating dose distributions.
Area of Science:
- Medical Physics
- Radiation Oncology
- Computational Physics
Background:
- Accurate dose calculation is crucial for effective radiation therapy.
- The VersaHD linear accelerator with Elekta Agility head is used for cancer treatment.
- Need for patient-specific quality assurance (PSQA) to verify treatment plans.
Purpose of the Study:
- To develop a comprehensive Monte Carlo simulation code using the Geant4 toolkit.
- To model the Elekta Agility head of the VersaHD linear accelerator.
- To support treatment planning and PSQA at Vietnam National Cancer Hospital.
Main Methods:
- Developed a Monte Carlo simulation code based on the Geant4 toolkit.
- Implemented functionality to read treatment logfiles and recalculate patient dose distributions.
- Validated the simulation model against experimental measurements using a water phantom and ionization chamber.
Main Results:
- The simulation code accurately models the Elekta Agility head.
- Gamma index analysis showed good agreement (3%/3mm) between simulated and measured lateral dose profiles.
- Percentage depth dose (PDD) analysis also showed satisfactory agreement (2%/2mm) with experimental data.
Conclusions:
- The developed Geant4-based Monte Carlo code is a reliable tool for modeling the Elekta Agility head.
- The code enables accurate recalculation of patient dose distributions for PSQA.
- This work supports advanced treatment planning and quality assurance in radiation oncology.
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