Electron arc therapy: beam data requirements and treatment planning.

Area of Science:

• Medical Physics
• Radiation Oncology

Background:

• Electron arc therapy uses a narrow beam swept across the patient.
• Beam data, including central axis percentage depth doses and off-axis ratios, vary with source-to-surface distance (SSD).
• Using fixed SSD data in effective SSD methods can introduce errors in isodose distributions.

Purpose of the Study:

• To implement and validate a treatment planning algorithm that accounts for SSD variations in electron arc therapy.
• To improve the accuracy of isodose distribution calculations in electron arc therapy.

Main Methods:

• Developed a treatment planning algorithm using beam data measured at two SSDs.
• Implemented interpolation and extrapolation procedures to handle SSD variations.
• Required off-axis ratios normal to the plane of rotation for off-axis calculations.

Main Results:

• The implemented algorithm effectively accounts for SSD variations.
• Calculated isodose distributions showed good agreement with film dosimetry measurements.
• The method improves accuracy compared to using fixed SSD data.

Conclusions:

• The developed algorithm enhances the accuracy of electron arc therapy dose calculations.
• Accounting for SSD variations is crucial for precise isodose distribution.
• This approach offers a more reliable method for treatment planning in electron arc therapy.