Scatter factors in proton therapy with a broad beam

Area of Science:

• Medical Physics
• Radiation Oncology

Background:

• Proton therapy requires accurate beam output calibration.
• Current calibration methods using phantoms differ from patient conditions, necessitating scatter factor correction.
• Existing scatter factors may include uncalibrated device effects.

Purpose of the Study:

• To develop and implement an estimator for the scatter factor in proton therapy.
• To improve the accuracy of dose delivery in proton therapy treatments.
• To validate the developed estimator against clinical measurements.

Main Methods:

• Developed a scatter factor estimator using a pencil beam algorithm within a treatment planning system (TPS).
• Calculated the scatter factor as the ratio of doses under identical conditions in the TPS.
• Evaluated the estimator's performance using clinical data from a gantry nozzle.

Main Results:

• The developed estimator demonstrated 2-3% differences between estimated and measured scatter factors.
• The estimator provides a method for calculating scatter factors within the TPS.
• Observed discrepancies attributed to dose calculation algorithm limitations.

Conclusions:

• The developed TPS-based estimator shows promise for accurate scatter factor estimation in proton therapy.
• Further refinement of dose calculation algorithms is needed to minimize discrepancies.
• This approach can enhance the precision of proton therapy dose delivery.