Comprehensive and Efficient Validation of Beam Modeling for a Proton Therapy System: Practical Considerations

Area of Science:

• Medical Physics
• Radiation Oncology

Background:

• Accurate beam modeling is critical for safe and effective proton therapy.
• Pencil beam scanning (PBS) systems need thorough validation before clinical use.
• This study presents a practical approach for comprehensive PBS model validation.

Purpose of the Study:

• To outline and implement a practical, efficient, and comprehensive validation process for a PBS beam model.
• To compare dose distributions calculated by treatment planning system (TPS) algorithms with measured data.
• To ensure the clinical readiness of the validated beam model.

Main Methods:

• Configured PBS beam model in TPS using measured beam data (IDD, lateral profiles, output).
• Performed validation tests per AAPM TG 185, TG 350 draft, and clinical insights.
• Included rectangular fields, PDD, planar dose (DigiPhant, MatriXX PT), and end-to-end tests in water and animal tissue.
• Compared TPS calculations (PCS, Acuros Protons) with measurements; peer review conducted.

Main Results:

• TPS calculations showed good agreement with measurements: point dose difference < 3%, planar dose 3%/3mm > 95%.
• Range differences in animal tissues were within 3%.
• Independent peer measurements confirmed machine output agreement within 1%.

Conclusions:

• Validated TPS beam models (PCS, Acuros PT) demonstrate good agreement between calculated and measured dose distributions.
• The validated model is suitable for clinical implementation in proton therapy.
• Practical considerations are key for efficient beam commissioning and validation.